SwePub - search: WFRF:(Esmaily Mohsen 1987)

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1.	Esmaily, Mohsen, 1987, et al. (author) A new semi-solid casting technique for fabricating SiC-reinforced Mg alloys matrix composites 2016 In: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 94, s. 176-189 Journal article (peer-reviewed)abstract The capability of the newly developed rheocasting (RC) technique in combination with the RheoMetal process for producing SiC particulate-reinforced AM50 and AZ91D matrix composites (Mg-based MMCs) was investigated. The quality of the MMCs was studied by analyzing the fraction of casting pores, number density of SiC clusters and the uniformity of SiC particles. Solid fraction, particle size and oxidation of SiC particles had strong impacts on the overall quality of the MMCs. The MMCs produced by 40% solid fraction and oxidized micron-sized SiC particles exhibited an excellent casting quality. A low-quality MMC was obtained when non-oxidized sub-micron sized SiC particles were employed. The results showed the formation of various types intermetallic particles and carbides such as MgO, Mg2Si, Al2MgC2, Mg2C3, Al4C3 as the interfacial reaction products of SiC/Mg alloy's melts. Mg hydride (alpha-MgH2) was also identified in inter-dendritic regions of the MMCs for the first time.
2.	Esmaily, Mohsen, 1987, et al. (author) A ToF-SIMS investigation of the corrosion behavior of Mg alloy AM50 in atmospheric environments 2016 In: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 360, s. 98-106 Journal article (peer-reviewed)abstract The redistribution of chloride and sodium ions after the NaCl-induced atmospheric corrosion of Mg alloy AM50 was investigated by means of Time-of-Flight Ion Mass Spectroscopy (ToF-SIMS). The samples were exposed at 4 and 22 degrees C in the presence of 400 ppm CO2. The results confirm the presence of less conductive electrolyte, and thus, less movement of ionic species (including sodium and chloride) in the electrolyte layer formed on the surface of samples exposed at the sub-zero temperature. Besides, ToFSIMS analysis showed the presence of an Al-containing surface film formed on the alloy surface after exposure at high relative humidity.
3.	Esmaily, Mohsen, 1987, et al. (author) Achieving superior corrosion resistance in friction stir processed AA6005-T6 aluminum alloy joints 2015 In: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; 64:26, s. 29-43 Conference paper (peer-reviewed)abstract In this study, ultra-fine grained (UFG) structure was produced in the stir zone (SZ) of AA6005-T6 alloy joints using friction stir processing (FSP) cooled by liquid nitrogen (N 2 ). Conventional friction stir welding (FSW) was used to fabricate reference joints. The corrosion properties of the cooled joints were investigated by atmospheric corrosion tests. The corrosion exposures were carried out at a relative humidity (RH) of 95%, 400 ppm CO 2 and at 22°C. The rapidly cooled joints exhibited exceptional corrosion resistance in both corrosion experiments as well as better mechanical properties compared to those of the FSWed joints. The better corrosion resistance of the quenched sample was attributed to the microstructural modification of the joint.
4.	Esmaily, Mohsen, 1987, et al. (author) Atmospheric Corrosion of Mg Alloy AZ91D Fabricated by aSemi-Solid Casting Technique: The Influence of Microstructure 2015 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:7, s. C311-C321 Journal article (peer-reviewed)abstract The atmospheric corrosion behavior of alloy AZ91D produced by a semi-solid metal (SSM) technique and by conventional high pressure die casting (HPDC) was investigated for up to 1176 hours in the laboratory. Alloy AZ91D in the SSM state was fabricated using a rheocasting (RC) technique in which the slurry was prepared by the RheoMetal process. Exposures were performed in 95% RH air at 22 and 4 degrees C. The RC alloy AZ91D exhibited significantly better corrosion resistance than the HPDC material at two temperatures studied. The effect of casting technology on corrosion is explained in terms of the microstructural differences between the materials. For example, the larger number density of cathodic beta phase particles in the HPDC material initially causes relatively rapid corrosion compared to the RC material. During later stages of corrosion, the more network-like beta phase particles in the RC alloy act as a corrosion barrier, further improving the relative corrosion resistance of the RC material.
5.	Esmaily, Mohsen, 1987, et al. (author) Bobbin and conventional friction stir welding of thick extruded AA6005-T6 profiles 2016 In: Materials and Design. - : Elsevier BV. - 1873-4197 .- 0264-1275. ; 108, s. 114-125 Journal article (peer-reviewed)abstract Conventional and bobbin friction stir welding processes (FSW and BFSW, respectively) were employed for joining 10 mm thick extruded AA6005-T6 profiles. The FSW and BFSW techniques were employed using two sets of parameters resulting in slow and fast processes. In general, the bobbin tool enabled welding with faster welding speeds than the conventional FSW technique. A comprehensive in-situ thermal analysis was performed using thermocouples. It was evident that, in a like-for-like comparison, i.e., employing the same set of welding parameters, the BFSW technique introduces a somewhat higher peak temperature, however, lower heat input and, more importantly, a higher cooling rate than the conventional FSW. Accordingly, a somewhat finer microstructure was formed in the stir zone of the BFSW samples than in the FSW ones, resulting in higher hardness values, and slightly higher ultimate strengths in the BFSW samples.
6.	Esmaily, Mohsen, 1987, et al. (author) Corrosion behavior of alloy AM50 in semi-solid cast and high pressure die cast states in cyclic conditions 2015 In: Corrosion. - : Association for Materials Protection and Performance (AMPP). - 0010-9312 .- 1938-159X. ; 71:6, s. 737-748 Journal article (peer-reviewed)abstract The atmospheric corrosion behavior of the Mg-Al alloy AM50 produced by high pressure die casting (HPDC) and a semi-solid metal (SSM) technique was studied under alternating wet-dry conditions for up to 672 hours. The alloy AM50 in the SSC state was fabricated using rheocasting (RC) technique in which the slurry was prepared by the newly developed RheoMetal process. To simulate the real-world atmospheric environment, the exposure program included a 6 hour wet phase (including rain with 0.5 % NaCl), a 2.5 hours transition phase followed by a 15.5 hours dry phase at 50°C and 70% relative humidity (RH). The results showed that the RC alloy was substantially less prone to corrosion than the HPDC material in the cyclic wet/dry atmosphere. Based on the gravimetric results and microstructural characterization studies, this was attributed to a lower fraction of porosity and to the barrier role of β phase particles in the RC.
7.	Esmaily, Mohsen, 1987, et al. (author) Corrosion behaviour of friction stir-welded AA6005-T6 using a bobbin tool 2016 In: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 111, s. 98-109 Journal article (peer-reviewed)abstract The atmospheric corrosion of extruded AA6005-T6 weldments produced with bobbin friction stir welding (BFSW) using fast and slow process parameters has been analyzed. The weldments of the same material fabricated using conventional FSW were also exposed as reference. Copper-rich phase particles were detected at the grain boundaries in the stir zone of both specimens. It was evident that the BFSW specimens exhibit better corrosion behaviour than the specimens produced using the slow process parameters. An effort was made to carefully attribute the improved corrosion resistance of the fast BFSW specimens to the difference in the microstructure of the weldments. (C) 2016 Elsevier Ltd. All rights reserved.
8.	Esmaily, Mohsen, 1987, et al. (author) Corrosion of Magnesium-Aluminum (Mg-Al) Alloys-An Interplay Between Al Content and CO2 2017 In: Minerals, Metals and Materials Series. - Cham : Springer International Publishing. - 2367-1696 .- 2367-1181. - 9783319523927 ; Part F8, s. 397-403 Conference paper (peer-reviewed)abstract In course of their practical applications, magnesium-aluminum (Mg-Al) alloys are frequently exposed to the ambient atmospheric, and thus, are susceptible to environmental degradation. In this study, we exposed several Mg-Al alloys (including AM20, AZ31, AM50, and AZ91) with different Al content to atmospheric environment to examine the effect of most important environmental factor, i.e., carbon dioxide (CO2) and its relation to the alloys' Al content. The surface films formed on alloys at two temperatures (-4 and 22 degrees C) were examined using auger electron spectroscopy (AES). The results show that CO2 inhibits long-term atmospheric corrosion behavior of the alloys and that the thickness of the carbon-rich layer in the surface film increases with increasing Al content. We suggest that; (a) the inhibitive effect of CO2 on the atmospheric corrosion behavior of Mg-Al systems, and (b) the positive influence of Al content on the corrosion performance of Mg-Al alloys are partly linked to the occurrence of compounds that exhibit characteristics close to that of the layered double hydroxides (LDHs).
9.	Esmaily, Mohsen, 1987, et al. (author) Effect of Rheocasting on Corrosion of AM50 Mg Alloy 2015 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:3, s. C85-C95 Journal article (peer-reviewed)abstract The corrosion behavior of magnesium-aluminum (Mg-Al) alloy AM50 produced by a rheocasting (RC) technique was examined in the presence and absence of CO2 at three temperatures -4, 4 and 22 degrees C. The slurry preparation in the RC material was performed with the newly developed RheoMetal process. For reference, 99.97% Mg was included in the corrosion exposures. The influence of the microstructure on the atmospheric corrosion of alloy AM50 produced by RC and high pressure die casting (HPDC) was investigated. The RC AM50 alloy showed better corrosion resistance than HPDC AM50 in all the exposure environments studied. For both materials, there was a strong positive correlation between temperature and the atmospheric corrosion rate. The superior atmospheric corrosion behavior of RC AM50 compared to HPDC AM50 is carefully discussed in relation to differences in the as-cast microstructure. This study demonstrates that producing the alloy AM50 by this type of RC technique opens the door to Mg-Al alloys as a promising candidate for various applications where corrosion resistance is of importance.
10.	Esmaily, Mohsen, 1987, et al. (author) Evidence for an unusual temperature dependence of the atmospheric corrosion of zinc 2016 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 163:14, s. C864-C872 Journal article (peer-reviewed)abstract The atmospheric corrosion behavior of zinc in the presence of NaCl has been investigated using well-controlled laboratory exposures in 95% RH air at ten different temperatures in the range -4 to 22°C. Results show that a critical temperature (? -0.5°C) exists in zinc corrosion above which the rate of corrosion is constant/independent of temperature, and, below which there is a positive correlation between temperature and corrosion rate. The corrosion products formed above and below -0.5°C are also entirely different. While simonkolleite, hydrozincite and zinc carbonate hydroxide are the main corrosion products at T ?-0.5°C, the same compounds are absent at T
11.	Esmaily, Mohsen, 1987, et al. (author) Fundamentals and advances in magnesium alloy corrosion 2017 In: Progress in Materials Science. - : Elsevier BV. - 0079-6425. ; 89, s. 92-193 Research review (peer-reviewed)abstract There remains growing interest in magnesium (Mg) and its alloys, as they are the lightest structural metallic materials. Mg alloys have the potential to enable design of lighter engineered systems, including positive implications for reduced energy consumption. Furthermore, Mg alloys are also emerging as viable biodegradable materials and battery electrodes. In spite of the greatest historical Mg usage at present, the wider use of Mg alloys remains restricted by a number of inherent limitations, including vulnerability to corrosion, poor formability and low creep resistance. This review covers recent research that has led to advances in Mg-alloy corrosion; including the application of contemporary methods for understanding Mg corrosion, the establishment of an electrochemical framework for Mg corrosion, illumination of alloying effects, and attempts at corrosion resistant Mg alloys. A discussion drawing from many sources provides an unbiased focus on new achievements, as well as some contentious issues in the field. The electrochemistry of Mg is reviewed in detail, including so-called anodic hydrogen evolution and cathodic activation. This review also covers atmospheric corrosion, and biodegradable Mg alloys. Finally, past and present trends in the field of Mg corrosion are reviewed, identifying knowledge gaps, whilst attempting to also identify future developments and directions.
12.	Esmaily, Mohsen, 1987, et al. (author) Influence of Multi-Pass Friction Stir Processing on the Corrosion Behavior of an Al-Mg-Si Alloy 2016 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 163:3, s. C124-C130 Journal article (peer-reviewed)abstract The effect of multi-pass (100% overlap) friction stir processing (FSP) on the NaCl-induced atmospheric corrosion behavior of an extruded 6005-T6 aluminum alloy has been studied. Samples were contaminated with 70 and 200 mu g/cm(2) NaCl and exposed in the presence of 400 ppm CO2 for a time interval of 200-3200 h. The results showed that increasing the number of passes gives rise to several crucial changes in the microstructure of the processed regions. Gravimetric analyses and morphological inspections of the corroded samples revealed that multi-pass FSP has also a significant impact on the NaCl-induced atmospheric corrosion behavior of the FS processed samples. While increasing the number of FSP passes resulted in a reduced extent of pitting corrosion in the stir zone, it induced a significant pitting corrosion attack in the heat affected zone of the samples, which were shown to be linked to a reduction in the size of intermetallic particles in the stir zone of the multi-pass FSP specimens. The results also showed that the cathodic activity of intermetallic particles in this family of Al alloys is size-dependent. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.
13.	Esmaily, Mohsen, 1987, et al. (author) Influence of temperature on the atmospheric corrosion of the Mg–Al alloy AM50 2015 In: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 90, s. 420-433 Journal article (peer-reviewed)abstract The effect of temperature on the NaCl-induced atmospheric corrosion of the Mg–Al alloy AM50 has been investigated in the laboratory. The corroded samples were analyzed gravimetrically and by SEM, EDX, XRD, and FTIR. The atmospheric corrosion of 99.97% Mg was also studied for reference. While the NaCl-induced atmospheric corrosion of AM50 is strongly reduced with decreasing temperature, 99.97% Mg does not exhibit such a trend. The temperature dependence of the atmospheric corrosion of alloy AM50 is attributed to the aluminum content in the alloy. Several crystalline magnesium hydroxy carbonates formed at 4 and 22 °C but were absent at −4 °C.
14.	Esmaily, Mohsen, 1987, et al. (author) Influence of temperature on the atmospheric corrosion of the MgAl alloy AM50 produced by semi-solid cast and high pressure die cast technique 2013 In: Proceedings of the International Congress on Light Materials-Science and Technology (LightMAT 2013), Bremen, Germany, In: Characterisation, Simulation, In: Corrosion, Editor: A. Lohmüller. Conference paper (peer-reviewed)abstract The effect of temperature on the atmospheric corrosion of the MgAl alloy AM50 was investigated in the laboratory. The alloy was investigated in both semi-solid cast and high pressure die cast form. Polished samples were exposed to air containing 400ppm CO2 for up to 4 weeks at 22ºC, 4ºC and -4oC at 95% relative humidity (RH). The rate of corrosion was determined by mass gain and metal loss measurements. The corrosion products were analyzed by SEM/EDX. Analysis by XRD showed that the composition of the crystalline corrosion product depended on the exposure temperature. Both materials exhibited a strong positive correlation between temperature and the rate of NaCl-induced atmospheric corrosion. It is suggested that the temperature dependence of corrosion is related to the dissolution of alumina in the passive film. The semi-solid cast material exhibited lower average corrosion rates at all three temperatures.
15.	Esmaily, Mohsen, 1987, et al. (author) Microstructural characterization and formation of α' martensite phase in Ti-6Al-4V alloy butt joints produced by friction stir and gas tungsten arc welding processes 2013 In: Materials and Design. - : Elsevier BV. - 0261-3069 .- 1873-4197 .- 0264-1275. ; 47, s. 143-150 Journal article (peer-reviewed)abstract The obtained microstructures of a Ti-6Al-4V alloy welded by Gas Tungsten Arc Welding (GTAW) and Friction Stir Welding (FSW) were investigated and evaluated quantitatively. In the GTAW method, the effect of current was examined so that the samples were subjected to various currents between 90 and 120. A. In the FSW process, samples were welded by different rotational speeds (450-850. rpm). Non-destructive tests including Visual and Radiography Tests (VT and RT) were used to identify defect-free samples. The microstructural studies by electron microscopes revealed formation of different phases in the weld area of the samples welded via mentioned methods. The recorded peak temperatures in the weld regions compared favorably with the expectations about the evolved microstructures. A bi-modal microstructure was just obtained in the FSWed sample with a peak temperature below β transus temperature (T<995°C). α' martensite phase, which is an acicular and strengthening phase in this alloy, was only observed in FSWed specimens.
16.	Esmaily, Mohsen, 1987, et al. (author) Microstructural characterization of the Mg-Al alloy AM50 produced by a newly developed rheo-casting process 2014 In: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 95, s. 50-64 Journal article (peer-reviewed)abstract The microstructure of rheo-cast Mg-Al alloy AM50 produced by the RheoMetal process is investigated and compared with the same alloy produced by conventional high pressure die casting. The size and arrangement of microstructural constituents and pores are characterized quantitatively using image analyzing techniques. The nearest neighbor distribution of the intermetallic particles is determined. The area fraction of porosity in rheo-cast AM50 is about half that found in the high pressure die cast alloy. In rheo-cast material, the distribution of p phase (Mg17Al12) is relatively uniform throughout the cast. In contrast, the beta phase particles tend to form macroscopic agglomerates in high pressure die cast material. The externally solidified grains in the rheo-cast material exhibit a smaller aluminum gradient than in the high pressure die cast alloy. This indicates that the solidification of the rheo-cast material is closer to equilibrium.
17.	Esmaily, Mohsen, 1987, et al. (author) New insights into the corrosion of magnesium alloys - The role of aluminum 2016 In: Scripta Materialia. - : Elsevier BV. - 1359-6462. ; 115, s. 91-95 Journal article (peer-reviewed)abstract The atmospheric corrosion of several Mg-Al alloys was investigated at -4,4 and 22 degrees C. The rate of corrosion increased with increasing temperature and decreasing Al content. Also, the effect of temperature became stronger with increasing Al content. The cast microstructure was found to influence both the average corrosion rate and the temperature dependence of corrosion. The influence of Al on corrosion and on the temperature dependence of corrosion is discussed in terms of the AI enriched layer in the bottom of the surface film and the breakdown of the same layer by chloride ions.
18.	Esmaily, Mohsen, 1987, et al. (author) On the capability of in-situ exposure in an environmental scanning electron microscope for investigating the atmospheric corrosion of magnesium 2015 In: Ultramicroscopy. - : Elsevier BV. - 1879-2723 .- 0304-3991. ; 153, s. 45-54 Journal article (peer-reviewed)abstract The feasibility of environmental scanning electron microscope (BEM) in studying the atmospheric corrosion behavior of 99.97% Mg was investigated. For reference, ex-situ exposure was performed. A model system was designed by spraying few salt particles on the metal surface and further promoting the corrosion process using platinum (Pt) deposition in the form of 1 x 1 x 1 pm(3) dots around the salt particles to create strong artificial cathodic sites. The results showed that the electron beam play a significant role in the corrosion process of scanned regions. This was attributed to the irradiation damage occurring on the metal surface during the BEM in-situ experiment. After achieving to a reliable process route, in a successful attempt, the morphology and composition of the corrosion products formed in-situ in the ESEM were in agreement with those of the sample exposed ex-situ.
19.	Esmaily, Mohsen, 1987, et al. (author) On the microstructure and corrosion behavior of AZ91/SiC composites produced by rheocasting 2016 In: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 180, s. 29-37 Journal article (peer-reviewed)abstract The microstructure and atmospheric corrosion behavior of two types of SiC (10 vol%)-reinforced magnesium alloy metal matrix composites (Mg alloy AZ91D-based MMCs) produced by rheocasting (RC) were investigated and compared to the monolithic alloy. Micron-sized and nano-sized SiC particles were used for fabrication of the MMCs. Microstructural studies using a broad range of analytical techniques showed the formation Al carbides and MgO at the alpha-Mg/SiC interface. The higher corrosion rate of the MMCs than RC AZ91D was attributed to a lesser degree of connectivity of the beta phase, the high impurity level of SiC-reinforced MMCs and also the higher fraction of casting pores in the MMCs as compared to the RC alloy.
20.	Esmaily, Mohsen, 1987, et al. (author) Oxidation and electrical properties of chromium–iron alloys in a corrosive molten electrolyte environment 2020 In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 10, s. 1-19 Journal article (peer-reviewed)abstract Chromium–iron (CrFe) binary alloys have recently been proposed to serve as the “inert” anode for molten oxide electrolysis (MOE). Herein, the effects of anodic polarization on physical and functional properties of CrFe anodes in the corrosive environment of MOE are studied via empirical observations and theoretical calculations. The findings indicate that the alloys form an inner chromia–alumina solid-solution covered by an MgCr2O4 spinel layer. A survey into the electrical properties of the detected oxides suggests that the layered oxide scale function as an efficient conductor of electricity at elevated temperature. The formation mechanism of the oxides is also investigated.
21.	Esmaily, Mohsen, 1987, et al. (author) Technical note: A major loss in tensile strength of friction stir welded aluminum alloy joints resulting from atmospheric corrosion 2016 In: Corrosion. - : Association for Materials Protection and Performance (AMPP). - 0010-9312 .- 1938-159X. ; 72:12, s. 1587-1596 Journal article (peer-reviewed)abstract The effect of corrosion on the mechanical properties of aluminum alloy (AA6005-T6) joints produced by friction stir welding is investigated. The tensile strength of the weldments was analyzed after 100 h exposure to 95% relative humidity air at 22°C in the presence of NaCl and CO2. The corrosion exposure caused a significant decrease in the ultimate tensile strength and ductility of the welds. Microstructural studies revealed that the loss of mechanical properties is associated with corrosion in the vicinity of the joint line remnants (JLRs), which are commonly found in friction stir welds. The reasons behind the preferential corrosion of the JLRs and the effect of corrosion on the mechanical properties of the welds are discussed.
22.	Esmaily, Mohsen, 1987 (author) The effect of microstructure and temperature on the atmospheric corrosion of Mg-Al alloys 2013 Licentiate thesis (other academic/artistic)abstract The NaCl-induced atmospheric corrosion behavior of the Mg-Al alloy AM50 produced by rheo-casting (RC) and high pressure die casting (HPDC) techniques was studied in the laboratory. The exposures were performed at 95% RH in the absence and presence of 400 ppm CO2 at 22, 4 and -4ºC. In parallel, 99.97%Mg was investigated as reference. The synergistic effects of microstructure, exposure temperature, CO2, amount of added NaCl and exposure time on the corrosion rate and corrosion products were systematically investigated gravimetrically and by means of OM, SEM/EDX, FIB/SEM, BIB, Tof-SIMS, XRD and FTIR. It is shown that the NaCl-induced atmospheric corrosion resistance of the RC material is consistently better than that of the HPDC material. The better corrosion resistance is attributed to differences in the as-cast microstructures. The RC material contains a higher fraction of intermetallic β phase with more continuous and network-like morphology than the HPDC AM50. The results provide new insights into the effect of microstructure on the atmospheric corrosion behavior of Mg-Al alloys. There is a strong positive correlation between exposure temperature and the rate of atmospheric corrosion. Thus, a decrease in temperature from 22 to -4ºC resulted in considerably slower corrosion both for the RC and the HPDC materials. The influence of temperature is suggested to be mainly related to the Al content. A corrosion product with an unknown phase (by XRD) and a non-crystalline corrosion product (by FTIR) were detected at sub-zero temperature.
23.	Esmaily, Mohsen, 1987, et al. (author) The influence of SO2 on the corrosion of Mg and Mg-Al alloys 2015 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:6, s. C260-C269 Journal article (peer-reviewed)abstract The SO2-induced atmospheric corrosion of some magnesium-aluminum (Mg-Al) alloys, including Mg alloy AZ91D, and commercially pure Mg (CP Mg) was investigated using well-controlled laboratory exposures and included real-time measurements of SO2 deposition. The influence of SO2 concentration, alloy composition, humidity, and ppb level additions of O-3 or NO2 on the rate of SO2 deposition was investigated. SO2 accelerates the corrosion of Mg and Mg alloys causing localized corrosion, MgSO(3)6H(2)O being the dominant corrosion product. At 60% RH, traces of O-3 or NO2 strongly increased both the SO2 deposition and the corrosion rate. The rate of SO2 deposition was strongly dependent on humidity; at 70% RH and higher the SO2 deposition rate was very rapid and constant in time while it was transient below 50% RH. At 60% RH, a change from transient to rapid, steady-state, SO2 deposition occurred. The sudden activation is explained by the onset of electrochemical corrosion. The activation behavior was shown to depend on SO2 concentration, the thickness of the surface film and by the presence of ambient O-2. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.
24.	Esmaily, Mohsen, 1987 (author) The Role of Microstructure in the Atmospheric Corrosion of Selected Light Alloys and Composites 2016 Doctoral thesis (other academic/artistic)abstract Magnesium-aluminum (Mg-Al) alloys, Mg-based metal matrix composites (MMCs) and Al alloys are among the best material candidates for future lightweight solutions. However, the use of these materials is limited by a number of issues, including the ability to resist corrosion. For example, Mg alloys and Mg-based MMCs exhibit relatively poor corrosion resistance in many environments and there are issues in the corrosion behavior of Al alloy weldments. This thesis aims to provide new knowledge on the role played by microstructure for the corrosion properties of light materials. The corrosion studies were done using well-controlled laboratory exposures and lasted 10-3200 h. The rate of corrosion was determined and the composition of the corrosion products was investigated using several techniques. The alloy microstructure and the microstructure of corrosion was investigated using a wide range of techniques, including TEM/EDX/EELS and statistical approaches. Cross sections and thin foils were produced using BIB and FIB milling methods. The atmospheric corrosion of several Mg-Al alloys was investigated and the influence of various environmental parameters, such as exposure temperature, chloride ions, CO2, and SO2 was studied. Alloys produced by the newly developed rheocasting (RC) technique were found to be more corrosion resistant than their high pressure die-cast (HPDC) counterparts. The superior corrosion resistance of the RC materials was explained in terms of differences in the alloy microstructure, based on a systematic characterization of the micro-constituents at macro, micro and nanoscales. The rate of corrosion decreased with increasing Al content and the atmospheric corrosion of Mg-Al alloys exhibited a strong positive correlation with temperature. It was proposed that the temperature dependence of corrosion was linked to the chloride-assisted breakdown of an Al3+- rich layer, which was detected in the bottom part of the surface film formed on Mg-Al alloys. Mg-Al alloys-based MMCs were produced by the RC method. The microstructure of the composites was investigated and the products the interfacial reactions were identified. The reaction products included a hitherto unknown Al carbide (AlC2) and MgH2. The MMCs corroded faster than the monolithic alloy. However, it was shown that the corrosion resistance of Mg alloy-based MMCs can be improved by selecting appropriate process parameters.The corrosion behavior of an Al alloy (6xxx series), which was welded/processed using friction stir welding (FSW), and its variants bobbin friction stir welding (BFSW) and friction stir processing (FSP) was investigated. The thermal history of the specimens was investigated in detail. As expected, the heat affected zones (HAZs) were most susceptible to the atmospheric corrosion. The extent of corrosion in the HAZ was proportional to the size of iron- and silicon-rich intermetallic particles in the stir zone (SZ). The formation of intermetallic compounds (IMCs) in Al/Mg dissimilar FSW joints was investigated.
25.	Heidarzadeh, A., et al. (author) Prediction of grain size and mechanical properties in friction stir welded pure copper joints using a thermal model 2015 In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 77:9-12, s. 1819-1829 Journal article (peer-reviewed)abstract In this study, a thermal model was developed and applied to simulate the friction stir welding of pure copper plates with the thickness of 2 mm. The different traverse speeds of 100, 200, 300, and 400 mm min(-1) and rotational speeds of 400, 700, 900 rev min(-1) were considered as welding parameters. Microstructural characterization, hardness measurement, tensile test, and fractography were conducted experimentally. The comparison between the numerical and experimental results showed that the developed model was practically accurate. In addition, the results confirmed that the peak temperature was the dominant factor controlling the grain size and mechanical properties, where the fine grains could be achieved at low rotational speed as well as high traverse speed. Consequently, lower peak temperature leads to the high ultimate tensile strength and hardness and the low elongation values.
26.	Heidarzadeh, A., et al. (author) Tensile Properties of Friction Stir Welds of AA 7020 Aluminum Alloy 2015 In: Transactions of the Indian Institute of Metals. - : Springer Science and Business Media LLC. - 0972-2815 .- 0975-1645. ; 68:5, s. 757-767 Journal article (peer-reviewed)abstract In this investigation, response surface methodology was used to predict and optimize the tensile properties of friction stir welded AA 7020 aluminum alloy. Tensile properties, microstructural features and fractography of the joints were measured and investigated using tensile test, optical and scanning electron microscopes, respectively. In addition, the influences of friction stir welding parameters on tensile properties of the joints were examined thoroughly. The results revealed that with increasing the heat input, the tensile strength of the joints increased up to a maximum value and then decreased, where the elongation of the joints increased continuously. Moreover, the optimal condition to obtain a maximum of tensile strength was 1,055 rpm, 97 mm/min and 7.4 kN, where as for tensile elongation was 1,320 rpm, 72 mm/min and 7 kN.
27.	Khodabakhshi, A., et al. (author) Effects of cold working and heat treatment on microstructure and wear behaviour of Cu–Be alloy C17200 2015 In: Tribology - Materials, Surfaces and Interfaces. - : Informa UK Limited. - 1751-584X .- 1751-5831. ; 9:3, s. 118-127 Journal article (peer-reviewed)abstract © 2015 Institute of Materials, Minerals and Mining and W. S. Maney & Son Ltd. The effects of cold work process between aging and solution heat treatment on the microstructure, hardness and the tribologic behaviour of a copper–beryllium (Cu–Be) alloy C17200 were investigated. The wear behaviour of the alloys was studied using ‘pin on disc’ method under dry conditions. The results show that the formation of fine grained structure and γ phase particles enhances the mechanical properties of the alloy; nonetheless, they do not reduce the wear rate. This is attributed to the capability of the softer specimens to maintain oxygen rich compounds during the dry sliding test.
28.	Mortazavi, A. N., et al. (author) Exploring failure modes of alumina scales on FeCrAl and FeNiCrAl alloys in a nitriding environment 2020 In: Acta Materialia. - : Elsevier BV. - 1359-6454. ; 201, s. 131-146 Journal article (peer-reviewed)abstract Two high-temperature FeCrAl and FeNiCrAl alloys were exposed in a strongly nitriding environment at 900 °C and the morphology of nitridation was studied. Quasi-in-situ experiments revealed that nitridation started at specific surface sites directly related to the alloy microstructure where the alumina scale was permeable to nitrogen. FeCrAl alloy grains with (112) orientation formed outward-growing alumina scales and were susceptible to nitridation. Outward-growing scales and substrate nitridation was also observed at chromium carbide precipitates in the FeNiCrAl alloy. Both alloys suffered nitridation at reactive element-rich (Y and Zr) inclusions larger than a certain critical size. The latter type of attack is caused by cracks and pores in the scale. The findings open new avenues of research for developing the next generation of high temperature alloys with superior properties.
29.	Mortazavi Seyedeh, Nooshin, 1986, et al. (author) Interplay of water and reactive elements in oxidation of alumina-forming alloys 2018 In: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 17:7, s. 610-617 Journal article (peer-reviewed)abstract High-temperature alloys are crucial to many important technologies that underpin our civilization. All these materials rely on forming an external oxide layer (scale) for corrosion protection. Despite decades of research on oxide scale growth, many open questions remain, including the crucial role of the so-called reactive elements and water. Here, we reveal the hitherto unknown interplay between reactive elements and water during alumina scale growth, causing a metastable ‘messy’ nano-structured alumina layer to form. We propose that reactive-element-decorated, hydroxylated interfaces between alumina nanograins enable water to access an inner cathode in the bottom of the scale, at odds with the established scale growth scenario. As evidence, hydride-nanodomains and reactive element/hydrogen (deuterium) co-variation are observed in the alumina scale. The defectrich alumina subsequently recrystallizes to form a protective scale. First-principles modelling is also performed to validate the RE effect. Our findings open up promising avenues in oxidation research and suggest ways to improve alloy properties.
30.	Mortazavi Seyedeh, Nooshin, 1986, et al. (author) The capability of Transmission Kikuchi Diffraction technique for characterizing nano-grained oxide scales formed on a FeCrAl stainless steel 2015 In: Materials Letters. - : Elsevier BV. - 1873-4979 .- 0167-577X. ; 147, s. 42-45 Journal article (peer-reviewed)abstract This letter focuses on the capability of Transmission Kikuchi Diffraction (TKD) in Scanning Electron Microscope (SEM) for obtaining microstructural and micro-textural information from nano-grained oxide scales formed on a FeCrAl alloy. Orientation maps, with an indexing rate of 85%, showed the formation of grains in the range 20-300 nm. TKD revealed the existence of an orientation relationship at the alloy/oxide interface as well as the presence of a single grain (40 nm) with spinel structure in the alumina scale. A pre-tilted sample holder was designed for 110 investigations at short working distances with minimized mechanical drift of the thin foils. (C) 2015 The Authors. Published by Elsevier B.V.
31.	Shahabi Navid, Mehrdad, 1986, et al. (author) NaCl-induced atmospheric corrosion of MgAl alloy AM50 in semi-solid cast and high pressure die cast form; relation between alloy microstructure and corrosion 2013 In: Proceedings of the International Congress on Light Materials-Science and Technology (LightMAT 2013), Bremen, Germany, In: Characterisation, Simulation, In: Corrosion, Editor: A. Lohmüller. Conference paper (peer-reviewed)abstract The atmospheric corrosion behavior of the MgAl alloy AM50 has been investigated in the laboratory, in the presence of 0, 14 and 70µg/cm2 NaCl. The alloy was investigated both as high pressure die cast and in semi-solid cast (rheocast) form. Polished samples were exposed for 1-672h in air at constant temperature (22.00oC) and constant relative humidity (95%). The concentration of CO2 was 0 or 400ppm. Corrosion rate was determined by measuring mass gain and metal loss. The microstructure of the two materials was examined through optical microscopy and SEM/EDX analyses. Cross sections were prepared through the corroded samples using focused ion beam (FIB) milling. The corrosion products were characterized by SEM/EDX and X-ray diffraction. The rheocast material was observed to exhibit better corrosion resistance than the high pressure die cast alloy. The relation between alloy microstructure and corrosion attack for the two materials is reported and discussed.
32.	Shahabi Navid, Mehrdad, 1986, et al. (author) NaCl-Induced Atmospheric Corrosion of the MgAl Alloy AM50-The Influence of CO2 2014 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 161:6, s. C277-C287 Journal article (peer-reviewed)abstract The NaCl-induced atmospheric corrosion of the MgAl alloy AM50 has been investigated using 99.97% Mg as reference. Polished samples were exposed up to 672 h in 95.0% RH air with 400 ppm or 0 ppm CO2 at 22.00°C. Samples were analyzed gravimetrically and by SEM/EDX, XRD and XPS. CO2 inhibited atmospheric corrosion with alloy AM50 corroding 6–7 times faster in the absence of CO2. Brucite and meixnerite (Mg6Al2(OH)18 × 4.5H2O) formed in the absence of CO2. In the presence of CO2 and NaCl three magnesium-hydroxy-carbonates, giorgiosite, hydromagnesite and Mg5(CO3)4(OH)2 × 8H2O formed. The influence of CO2 on the electrochemical corrosion process is discussed.
33.	Shahabi Navid, Mehrdad, 1986, et al. (author) NaCl-induced atmospheric corrosion of two MgAl alloys in semi-solid cast and diecast states - Influence of microstructure and CO2 2014 In: Materials Science and Technology Conference and Exhibition 2014, MS and T 2014, David L. Lawrence Convention CenterPittsburgh, United States, 12-16 October 2014. - 9781634397230 ; 2, s. 777-784 Conference paper (peer-reviewed)abstract The atmospheric corrosion of MgAl alloys AM50 and AZ91 was studied in the laboratory at constant (95.0%) relative humidity and 22°C, in the presence and absence of 400 ppm CO2. NaCl was added prior to exposure. The materials were in semi-solid cast (SSC) and pressure diecast (DC) states. Crystalline corrosion products were identified by X-ray diffraction (XRD). Alloy microstructure and corrosion morphology were characterized by scanning electron microscopy (SEM). Corrosion was more localized in CO2-free environment compared with air with 400 ppm CO2. The different corrosion behavior of the materials is discussed in terms of differences in the microstructure, especially the area fraction and distribution of β-phase. The surface film formed in the absence of NaCl was investigated by X-ray photoelectron spectroscopy (XPS).
34.	Shahabi Navid, Mehrdad, 1986, et al. (author) On the early stages of localised atmospheric corrosion of magnesium–aluminium alloys 2020 In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 10:1 Journal article (peer-reviewed)abstract The surface film on pure magnesium and two aluminium-containing magnesium alloys was characterised after 96 h at 95% RH and 22 °C. The concentration of CO2 was carefully controlled to be either 0 or 400 ppm. The exposed samples were investigated using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron microscopy. The results showed that when the alloys were exposed to the CO2-containing environment, aluminium cations (Al3+) was incorporated into a layered surface film comprising a partially “hydrated” MgO layer followed by Mg(OH)2, and magnesium hydroxy carbonates. The results indicated that aluminium-containing magnesium alloys exhibited considerably less localised corrosion in humid air than pure magnesium. Localised corrosion in the materials under investigation was attributed to film thinning by a dissolution/precipitation mechanism.

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