Yichuan PAN
材料科学技术（英文）
In this study, grain refining effect of Al-1.5C master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results show that addition of Al-1.5C master alloy leads to significant decrease of the mean grain size from about 270 μm to 50 μm at the center of the AZ63 alloy ingot. Grain refinement by carbon addition is mainly due to the heterogeneity nucleation on the Al-, C-, O-, Fe- and Mn-rich particles, but not constitutional undercooling caused by the carbon solute element. Fe plays an important role in the formation of the nucleating particles, but not acts as an inhibiting element.
关键词:
Grain refinement
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Materials Science and Technology
The transformation of precipitated phases of Zr(50.5)Cu(34.5-x)Ni(4)Al(11)Ag(x) alloy master ingots with Ag substitution of Cu was studied in detail by phase analysis. The precipitated (Zr-Cu) rich phases deteriorate the glass forming ability (GFA) of Zr(50.5)Cu(34.5)Ni(4)Al(11). Two new (Zr-Cu) rich phases, A1 with bcc structure and a=0.339 nm and A2 with fcc superlattice structure and a=1.21 nm, were identified by a transmission electron microscope. When x=2, A1 phase disappears, and A2 phase remains and is suppressed gradually with further Ag addition. When x=13, one precipitated phase with Ag more than 13 at-% begins to deteriorate GFA. In the view of chemistry, the precipitation of (Zr-Cu) rich phases means that the interaction between Cu and Zr atoms is rather drastic. The addition of Ag weakens the interaction between Cu and Zr. The similar competition mechanism proposed by the authors plays an important role in suppressing precipitated phases and improving GFAs.
关键词:
Phase transformation;Glass forming ability;Bulk metallic glass;Microstructure characterisation;bulk metallic glasses;cu-ni alloys;forming ability;supercooled;liquid;diameter;zrcu;mm;al
Pengfa FENG
材料科学技术（英文）
The influences of preparation conditions of Al-5Ti-B (as-cast and hot-rolled) and Al-10Sr (as-cast and hot-extruded) and melt treatment procedures on the grain refinement and modification performance of A356 alloy are experimentally studied. For the two master alloys, the 50% reduction is sufficient to meet the demands of the efficient grain refinement and modification of A356 alloy. When Al-5Ti-B is introduced into the melt prior to degassing, the grain refinement efficiency of Al-5Ti-B will be greatly increased due to the better dispersity of TiB2 particles. Al-5Ti-B master alloy is less prone to affect the modification effect of Al-10Sr when they are used together.
关键词:
Grain refinement
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中间合金
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热变形
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晶粒细化
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A356合金
X.F. Liu
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X.F. Bian
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X.G. Qi
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M. Thompson and J.J Ma (Colledge of Materials Science and Engineering
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Shandong University of Technology
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Jinan 250061
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China)
金属学报(英文版)
Nucleation sites of α-Al grains after addition of an Al-Ti-B master alloy into pure aluminium have been investigated using EPMA. The results show that either TiAl3 or boride particales can nucleate α-Al grains. But the number of TiAl3 nucleants is reduced with the holding time prolonged and the boride-nuclei are increasing gradually. Based on these results, a new refining method, adding molten Al-Ti-B into commercially pure aluminium, which has a quicker and better refining efficiency is presented.
关键词:
Al-Ti-B master alloy
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