| 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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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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| 3. |
- 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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| 4. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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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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| 5. |
- 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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| 6. |
- 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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| 7. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Influence of Multi-Pass Friction Stir Processing on the Corrosion Behavior of an Al-Mg-Si Alloy
- 2016
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 163:3, s. C124-C130
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Tidskriftsartikel (refereegranskat)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.
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| 8. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Microstructural characterization of the Mg-Al alloy AM50 produced by a newly developed rheo-casting process
- 2014
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 95, s. 50-64
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Tidskriftsartikel (refereegranskat)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.
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| 9. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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On the capability of in-situ exposure in an environmental scanning electron microscope for investigating the atmospheric corrosion of magnesium
- 2015
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Ingår i: Ultramicroscopy. - : Elsevier BV. - 1879-2723 .- 0304-3991. ; 153, s. 45-54
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Tidskriftsartikel (refereegranskat)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.
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| 10. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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On the microstructure and corrosion behavior of AZ91/SiC composites produced by rheocasting
- 2016
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 180, s. 29-37
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Tidskriftsartikel (refereegranskat)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.
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