Papers by MOHAMMED BSHER.ASMAEL
The effect of the rare earth element Y on the microstructure and hardness of (Mg-0.5Zn-0.5Zr-2.8N... more The effect of the rare earth element Y on the microstructure and hardness of (Mg-0.5Zn-0.5Zr-2.8Nd -1.5Gd) wt% Mg alloy investigated. 1 wt. % Y was added and compared with the base alloy. The microstructure results show the refinement of the grain by the addition of Y and the grains became smaller about 31.8 % and the volume fraction was increases 11.1% %, which led to the increment of hardness from 48.33 HV (as-cast EV31A) to 53.71 HV (as-cast EV31A +1 Y). Energy dispersive spectroscopy and X-ray diffraction results showed that the base alloy mainly contained α-Mg matrix and Mg-(Nd, Gd) as a second phase crystallized along the grain boundaries and addition of(Y) yttrium resulted in the formation of the new phase, Mg-Zn-Y-phase was found as a new ternary phase, where Y combined with the original second phase.
The influence of holmium on the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys were investi... more The influence of holmium on the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys were investigated. Conventional casting methods are used to produce the alloys. All the results were characterized by optical microscopy, scanning electron microscope (SEM) and the Vickers hardness test to highlight the influence of holmium addition. The addition of 2.0 wt.% holmium leads to the combination of rare earth elements which formed Mg-Zn-Nd-Ho phase. The results have shown the addition of Ho improved the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys. By adding grain size of 2.0 wt.% holmium had reduced by 18.43%, while the volume fraction increased by 7.34%. The Vickers hardness value improved 6.18% due to the grain refine and volume fraction precipitates. The 2.0 wt.% holmium addition showed a positive result in microstructure and hardness value.
In this research, computer-aided cooling curve thermal analysis, microstructure analysis, hardnes... more In this research, computer-aided cooling curve thermal analysis, microstructure analysis, hardness measurements, and tensile test were performed to investigate the effect of praseodymium (Pr) and erbium (Er) additions on as-cast ZRE1 magnesium (Mg) alloys. Results from the cooling curve and microstructure analysis showed that praseodymium and erbium altered the grain size of the alloys. Thermal analysis result demonstrated an increased solidification rate with praseodymium and erbium additions. Furthermore, the grain size was reduced by approximately 16 % and 15 % with the addition of praseodymium and erbium, respectively. Scanning electron microscopy/energy dispersive X-ray spectroscopy results showed that praseodymium combined with the original second phase and formed MgÀZn-PrÀCe, and erbium dissolved into the a-Mg matrix. Both additives improved the hardness and ultimate tensile strength of the ZRE1 magnesium alloy.
To cite this article: R. Ahmad , Z. M. Sheggaf, M. B. A. Asmael & M. Z. Hamzah (2017): Effect of ... more To cite this article: R. Ahmad , Z. M. Sheggaf, M. B. A. Asmael & M. Z. Hamzah (2017): Effect of rare earth addition on solidification characteristics and microstructure of ZRE1 magnesium cast alloy, Advances in Materials and Processing Technologies,
In this research, optical observations, X-ray diffraction and hardness measurements were used to ... more In this research, optical observations, X-ray diffraction and hardness measurements were used to investigate the effects of yttrium (Y) additions on as cast ZRE1 magnesium alloy. 0.75 wt.% Y was added and compared with the base alloy. The microstructure results show the refinement of the grain by the addition of Y and the grains became smaller about 32 %, which led to the increment of hardness from 50 HV (as-cast ZRE1) to 56.6 HV (as-cast ZRE1+0.75 Y).Energy dispersive spectroscopy (EDS) results showed that the base alloy mainly contained α-Mg matrix and Mg-Zn-Ce as a second phase crystallized along the grain boundaries and with the addition of Y, Mg-Zn-Y-Ce phase was found as a new second phase, where Y combined with the original second phase, which confirmed by the X-ray diffraction (XRD) results and also there is no other phases was formed by the Y addition.
The effects of 3 wt.% heavy rare earth Gadolinium (Gd) addition on the microstructure and mechani... more The effects of 3 wt.% heavy rare earth Gadolinium (Gd) addition on the microstructure and mechanical properties (Hardness) of as-cast Mg-Zn-Ce-Zr alloy (base alloy) were investigated using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectrum (EDS), X-ray diffraction (XRD) and Vickers hardness. The purpose of this research is to investigate the variations occured in grain size and the formation of intermetallics with Gd addition, as well as their effect on hardness. The results of microstructure indicated that Gd addition led to significant grain refinement, which decreased by 28%. Both grain refinement and hard secondary phases (Mg,Zn)12RE and (Mg,Zn)3RE led to the improvement in hardness of Mg-Zn-Ce-Zr by 34%.
The effect of thickness of vortex gating system on microstructure, velocity and porosity of A314 ... more The effect of thickness of vortex gating system on microstructure, velocity and porosity of A314 cast alloy was investigated. Three different thicknesses of 20, 25 and 30 mm were simulated and casted. The data of simulation showed the thicker gating reduced the velocity of the melt. In addition, increased thickness in vortex gate contributes to better eutectic interlaminar spacing. The best quality of casting (less porosity) was obtained with large thickness of vortex gating system.
The effect of 1 wt % Pr addition on ZRE1 cast alloy was investigated using Optical Microscope (OM... more The effect of 1 wt % Pr addition on ZRE1 cast alloy was investigated using Optical Microscope (OM), Scanning Electron Microscope (SEM), Energy-Dispersive Spectrum (EDS) and X-ray Diffraction (XRD). The purpose of this research is to investigate the variations in grain size and intermetallics formation with Pr addition, as well as their effect on hardness. The microstructure observations show that the grains became smaller with Pr addition, which lead to the increase of hardness of base alloy. EDS results showed that the base alloy mainly consists of α-Mg matrix and Mg-Zn-Ce as a second phase crystallized along the grain boundaries and when Pr was added, the Mg-Zn-Ce-Pr phase was formed, where Pr combined with the original second phase. The solubility of zinc and Pr in magnesium formed Zn-rich particles around grain boundaries.
Your article is protected by copyright and all rights are held exclusively by ASM International. ... more Your article is protected by copyright and all rights are held exclusively by ASM International. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to selfarchive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
Thermal analysis has become very important in foundry because it aids in studying the effect of a... more Thermal analysis has become very important in foundry because it aids in studying the effect of additives on eutectic growth temperature and assessing the quality of modifications. This research was performed to investigate the influence of the addition of Ce (0.1 1.0 wt. %) on the eutectic Al-Si-Cu-Mg alloy characteristics of solidification.
The effect of rare earth (RE) addition on diffusion and porosity deformation of Al-11Si-2Cu alloy... more The effect of rare earth (RE) addition on diffusion and porosity deformation of Al-11Si-2Cu alloy was investigated. The microstructure was characterized by optical microscope. By adding a small amount of La and Ce, the porosity can be reduced. As the amount of La and Ce was increased, the porosity defects were diffused and increased in microstructure. RE intermetallic indicates Al-Cu phase interrupted the quality of Al-Si-Cu casting alloy.
The effect of additive elements on impact toughness of Al-11Si-Cu alloy was investigated. The imp... more The effect of additive elements on impact toughness of Al-11Si-Cu alloy was investigated. The impact test bars were used as impact specimens. The energy of Al-11Si-Cu was improved with Sr modifier addition. The high ability of Ce and La to form large structure intermetallic in Al-Si-Cu will reduce the energy. The RE-intermetallic has an effect on impact analysis, which facilitates to increase the porosity pore.
This research was to determine the effect of Cerium and cooling rate on the microstructure of eut... more This research was to determine the effect of Cerium and cooling rate on the microstructure of eutectic Al-11Si-Cu-Mg cast alloy. The Cerium was added to produce Al-11Si-Cu-Mg-1.5Ce alloys. The microstructure was characterized by optical microscope. The Si structure was modified with the increase of the cooling rate, where smaller area was achieved. Ce formed rich intermetallic phase, such as Al-Si-Ce.
This study was to determine the influences of post-weld heat treatment (PWHT) on the tensile and ... more This study was to determine the influences of post-weld heat treatment (PWHT) on the tensile and microstructure properties of friction stir-welded AA6061 aluminum alloy joints. Friction stir welding (FSW) of aluminum alloys has the potential to retain good mechanical and metallurgical properties. 3 mm plate AA6061 aluminum alloy was used to fabricate the joints. Solution heat treatment, quenching plus an artificial aging treatment with different times of aging were adopted. The fracture surface of the welded specimens was analyzed by using a scanning electron microscope, and an optical microscope was used for microstructure analysis, where finer dimples were obtained and formed inter-metallic compound at the highest aging time. Tensile properties were improved by about 4.7% after PWHT for 16 hrs. In addition, hardness increased with the increase of the aging time at the top region. A simple artificial aging treatment was able to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.
This paper presents the experimental investigation conducted on ADC12 cast alloy. The main object... more This paper presents the experimental investigation conducted on ADC12 cast alloy. The main objective of the research is to investigate the effect of 1.5%La addition with different cooling rate on microstructure and hardness value of ADC12 cast alloy. The Ceramic Mold with different thickness dimensions was use to obtained different cooling rate. The Si structure became modified by increase the cooling rate of base alloy. With La addition the Si size observed smaller area than base alloy when the cooling rate increases. In addition, the higher cooling rate and La addition improves the hardness specially at lower thickness with La addition.
The effect of Cr addition on the fluidity of aluminum (LM6) alloy has been investigated by spiral... more The effect of Cr addition on the fluidity of aluminum (LM6) alloy has been investigated by spiral fluidity test. Presence of 0.1 wt.% Cr decreased fluidity of melt due to formation of sludge. In fact Cr changes the morphology of the intermetallic phase from β-intermetallics less harmful polyhedral morphology (α-intermetallics). The β-phases have largest surface to volume ratio, hence they have the largest interfacial region with the melt and are the most detrimental intermetallic to drop off the fluidity. In Cr-containing alloys the effect of α-phase is less detrimental than β-phase to the fluidity. On the other hand sludge formation and consuming Si and shifts the local chemical composition of the melt to the aluminum side of the phase diagram which has lower fluidity than eutectic and hypereutectic compositions.
This article investigates the effects of addition of alloying element on the impact toughness of ... more This article investigates the effects of addition of alloying element on the impact toughness of as-cast aluminum (LM6) alloy. Presence of 0.1 wt.% Cr increases the toughness up to 38%. In fact the sharp tips Fe intermetallics which have needle shape act as stress raisers with a general reduction of the ductility and ultimate tensile strength. On the other hand by increasing the Cr content in the base alloy the size distribution of the compounds becomes more spread. Therefore addition of Cr improves toughness impact by two mechanisms. First eliminating harmful βintermetallics and second providing microstructure with more spread particles.
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Papers by MOHAMMED BSHER.ASMAEL