| 1. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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A new semi-solid casting technique for fabricating SiC-reinforced Mg alloys matrix composites
- 2016
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Ingår i: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 94, s. 176-189
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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A ToF-SIMS investigation of the corrosion behavior of Mg alloy AM50 in atmospheric environments
- 2016
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 360, s. 98-106
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Tidskriftsartikel (refereegranskat)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.
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| 3. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Achieving superior corrosion resistance in friction stir processed AA6005-T6 aluminum alloy joints
- 2015
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; 64:26, s. 29-43
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Konferensbidrag (refereegranskat)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.
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| 4. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Atmospheric Corrosion of Mg Alloy AZ91D Fabricated by aSemi-Solid Casting Technique: The Influence of Microstructure
- 2015
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:7, s. C311-C321
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Tidskriftsartikel (refereegranskat)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.
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| 5. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Bobbin and conventional friction stir welding of thick extruded AA6005-T6 profiles
- 2016
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Ingår i: Materials and Design. - : Elsevier BV. - 1873-4197 .- 0264-1275. ; 108, s. 114-125
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Tidskriftsartikel (refereegranskat)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.
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| 6. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Corrosion behavior of alloy AM50 in semi-solid cast and high pressure die cast states in cyclic conditions
- 2015
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Ingår i: Corrosion. - : Association for Materials Protection and Performance (AMPP). - 0010-9312 .- 1938-159X. ; 71:6, s. 737-748
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Tidskriftsartikel (refereegranskat)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.
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| 7. |
- Esmaily, Mohsen, 1987, et al.
(författare)
-
Corrosion behaviour of friction stir-welded AA6005-T6 using a bobbin tool
- 2016
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 111, s. 98-109
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Tidskriftsartikel (refereegranskat)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.
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| 8. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Corrosion of Magnesium-Aluminum (Mg-Al) Alloys-An Interplay Between Al Content and CO2
- 2017
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Ingår i: Minerals, Metals and Materials Series. - Cham : Springer International Publishing. - 2367-1696 .- 2367-1181. - 9783319523927 ; Part F8, s. 397-403
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Konferensbidrag (refereegranskat)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).
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| 9. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Effect of Rheocasting on Corrosion of AM50 Mg Alloy
- 2015
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:3, s. C85-C95
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Tidskriftsartikel (refereegranskat)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.
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| 10. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Evidence for an unusual temperature dependence of the atmospheric corrosion of zinc
- 2016
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 163:14, s. C864-C872
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Tidskriftsartikel (refereegranskat)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
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