Abstract

Using the X-ray diffraction and electron microscopy methods, the structure and the elemental and phase compositions of hypereutectic alloy Al₈₆Ni₂Co₆Gd₆ (hereinafter, elemental composition in at %) are studied during melt solidification from 1500°C at a rate of 1000 degree/s under high pressures of 3 and 7 GPa. Melt solidification under high pressure leads to a change in the phase composition of the alloy and the formation of an abnormally supersaturated α-Al(Gd) solid solution. The following new phases were synthesized at a pressure of 7 GPa: the Al₃Gd* phase (of the Al₃U type) containing Co and Ni, which has primitive cubic structure cP4/2 with a lattice parameter of a = 4.285 ± 0.002 Å; the Al₈Co₄Gd* phase (of the Al₈Cr₄Gd type), which has tetragonal structure tI26/1 with parameters of a = 8.906 ± 0.003 Å and c = 5.150 ± 0.003 Å. The structure of all obtained samples is homogeneous, densely packed, and finely dispersed, without shrinkage cavities and pores. The average microhardness of the samples is high due to the formation of a solid solution and dispersion strengthening.

中文翻译：

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高压对 Al86Ni2Co6Gd6 合金中新化合物形成的影响

摘要

利用 X射线衍射和_电子显微镜方法，研究了_在1500 ° _C和在 3 和 7 GPa 的高压下的 1000 度/秒的速率。高压下的熔体凝固导致合金相组成发生变化，形成异常过饱和的α-Al(Gd)固溶体。在 7 GPa 的压力下合成了以下新相： 含有 Co 和 Ni 的 Al ₃ Gd* 相（Al ₃ U 型），具有原始立方结构cP4/2，晶格参数为a = 4.285 ± 0.002 Å；Al ₈ Co ₄ Gd* 相（Al ₈ Cr ₄ Gd 型），具有四方结构tI 26/1，参数为a = 8.906 ± 0.003 Å 和c = 5.150 ± 0.003 Å。所得样品结构均一、致密、分散细密，无缩孔和气孔。由于固溶体的形成和弥散强化，样品的平均显微硬度很高。