M.B.A. Asmael

Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

Influence of cerium on microstructure and solidification of eutectic Al–Si piston alloy

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. Field emission scanning electron microscopy (FESEM) and optical microscopy were employed to characterize the alloy microstructure. The main phases studied were the Al–Cu (Al2Cu) and Al–Si phases. The addition of Ce decreased the nucleation and growth temperatures and acted as a refiner for the alloy. The larger amounts of Ce significantly impacted the Si structure: the average Si particle size decreased as the Ce concentration was increased, which led to a finer grain structure. The Ce formed intermetallic compounds with the alloyed elements that had plate- or needle-like structures and that interrupted the modification of Si. The solidification parameters, including the growth and nucleation temperatures, increased with increasing change in the morphology of the Al–Cu phase that were caused by Ce addition.

Reduction in secondary dendrite arm spacing in cast eutectic Al–Si piston alloys by cerium addition

The effects of Ce on the secondary dendrite arm spacing (SDAS) and mechanical behavior of Al–Si–Cu–Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis (CA‒CCTA). The results showed that 0.1wt%–1.0wt% Ce addition resulted in a rapid solidification time, Δts, and low solidification temperature, ΔTS, whereas 0.1wt% Ce resulted in a fast solidification time, Δta–Al, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index (Q) and ultimate tensile strength of (UTS) Al–Si–Cu–Mg alloys significantly improved with the addition of 0.1wt% Ce. Moreover, the base alloy hardness was improved with increasing Ce concentration.

Effect of High Cerium and Lanthanum on Impact Toughness of Al-11Si-Cu Eutectic Cast Alloy

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.

Effect of Elements Cerium and Lanthanum on Eutectic Solidification of Al-Si-Cu near Eutectic Cast Alloy

The properties of Al-Si-Cu cast alloys are strongly affected by eutectic Al-Si and Al-Cu phases. The characteristic parameters of these two phases with additions cerium 1wt % (Ce) and lanthanum1 wt % (La) were investigated in Al-11Si-2Cu near eutectic alloy using computer-aided cooling curve thermal analysis. As a result, the La additive showed the highest (TNAl-Si) while the Ce additive showed very little effect. In addition, the growth temperature (TGAl-Si) is decreased by adding Ce compared to the base alloy and La addition. Additives showed an increase of recalescence magnitude (TRAl-Si). Addition La and Ce increased the nucleation and growth temperature of Al-Cu phase. The microstructure analysis on the silicon morphology showed that 1 wt % La and 1 wt % Ce additions play refiner role in Al-Si-Cu near eutectic alloys. Findings are also confirmed by aspect ratio of eutectic silicon phase.

Effect of pouring temperature on microstructure properties of Al-Si LM6 Alloy sand casting

In the present paper an experimental investigation on green sand casting of Al-Si cast alloy (LM6) has been conducted. The main objectives of the research were the effect of pouring temperature on microstructure property of green sand casting Al-Si LM6 Alloy. The high quality of The LM6 alloy was investigated by controlling the pouring temperature. The pattern was flat like and pouring was done with four different temperatures 630, 660, 690 and 720Cº. The obtained results showed that the pouring temperature has a significant influence on the quality of green sand casting of LM6 Al-Si alloy. The lower pouring temperature provides finer microstructure with fewer defects such as porosity.

The Influence of Holmium on the Microstructure and Hardness of Mg-Nd-Gd-Zn-Zr Alloys

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.

Surface modification of hypereutectic Al-Si alloy via friction stir process

The surfaces of cast hypereutectic Al-Si-Cu-Ni-La alloy plate was subjected to single pass Friction Stir Processing (FSP) with the aim of decreasing the Si and intermetallic particles size, porosity, and enhancing tensile properties. After FSP, the FS-processed sample shows an improvement in tensile strength value of about 27.5% compared to the as cast base alloy. Optical and scanning electron micrographs indicated that FSP significantly decreases the size of Si, intermetallic particles, and reduced porosity in the alloy, which contributed to the enhancement in tensile properties.

Effect of Mish Metal Cerium Addition on Fluidity of Aluminum Eutectic Silica Alloys - LM6

The evaluation of 0.1 to 1.0% of Ce addition effect on fluidity has been investigated. The fluidity of LM6 has decreased with the Ce addition. The effect of Ce can be shown very clearly with a high amount of 1% wt of Ce. The fluidity length of the composites is shorter than that of the LM6 base material. In spiral mold, the fluidity length is shortened when the weight percentage of Ce content is increased in the base metal LM6. Optical microscope images showed that the 1.0 % of Ce additive led to modification of silica morphology which reduced the fluidity length to 28%. The partial modification of silica can be observed clearly in small amount of Ce but it does not have large affect on the fluidity length.

Effect of Yttrium Addition on Microstructure and Hardness of Cast EV31A Magnesium Alloy

The effect of the rare earth (RE) 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 (EDS) and X-ray diffraction (XRD) 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.