Abstract

The purpose of this work is to study the possibility of the formation of new phases in the Al₈₆-Ni₆Co₄Gd₂Tb₂ alloy upon rapid solidification of its high-temperature melt under high pressure. Samples for research were obtained under high pressures of 3, 5, and 7 GPa in a high-pressure chamber of the “toroid” type. The chamber consists of flat hard alloy anvils pressed into steel rings. Alget stone was used as a pressure-transmitting medium. Heating and melting of the sample was carried out by passing an alternating current through the sample placed in a hexagonal boron nitride crucible. High pressure punches served as current leads. The temperature value was calculated on the basis of the thyristor readings, according to the current power. Cooling of the melts was carried out at a rate of 1000 deg/s, the temperature of the melt before quenching was 1500°C. Experimental scheme: pressure setting → pulse heating → holding at a set pressure and temperature → cooling without depressurization to room temperature → high pressure reduction to atmospheric. The microstructure of the samples of the alloy of the eutectic composition Al₈₆Ni₆Co₄Gd₂Tb₂, obtained depending on the quenching temperature (1500°C) and high pressure (3, 5, and 7 GPa), has been investigated by the methods of X-ray diffraction analysis, optical and electron microscopy. Cooling rate 1000 deg/s. Due to the combination of a high solidification rate and mechanical compaction under high pressure, samples of an alloy of the composition Al₈₆Ni₆Co₄Gd₂Tb₂ with a fine structure and high density were obtained. At pressures of 5–7 GPa, the formation of new phases was noted in the alloy: Al₃(Gd/Tb)* (of the Al₃U type), with a primitive cube structure (cP4/2) with a lattice parameter a = 4.285 ± 0.002 Å and Al₈(Ni/Co)₄Gd* (of the Al₈Cr₄Gd type) with a tetragonal structure (tI26/1) with parameters a = 8.906 ± 0.003 Å and c = 5.150 ± 0.003 Å. Studies have shown that the average microhardness of a sample obtained, in particular, under a pressure of 7 GPa, is high (~1700 MPa) due to solid solution and precipitation hardening. This is almost 2 times higher than in the original sample. The results obtained show the fundamental possibility of using the method of solidification of the melt under high pressure to change the level of properties of aluminum alloys used in industry without changing their chemical composition by modifying the structure and changing the composition of the structural components of the sample.

中文翻译：

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高压对Al86Ni6Co4Gd2Tb2液态合金凝固的影响

摘要

这项工作的目的是研究在 Al ₈₆ -Ni ₆ Co ₄ Gd ₂ Tb _{2中形成新相的可能性}合金在高压下高温熔体快速凝固。用于研究的样品是在“环形”型高压室中 3、5 和 7 GPa 的高压下获得的。腔室由压入钢环中的扁平硬质合金砧座组成。Alget石被用作压力传递介质。通过使放置在六方氮化硼坩埚中的样品流过交流电来进行样品的加热和熔化。高压冲头用作电流引线。温度值是根据当前功率根据晶闸管读数计算得出的。熔体的冷却以1000度/秒的速率进行，熔体在淬火前的温度为1500℃。实验方案：压力设定→脉冲加热→保持在设定的压力和温度→不减压冷却至室温→高压减压至大气。共晶成分 Al 合金样品的微观结构₈₆ Ni ₆ Co ₄ Gd ₂ Tb ₂，根据淬火温度（1500°C）和高压（3、5和7 GPa）获得，已通过X射线衍射分析，光学和电子方法进行了研究显微镜。冷却速率 1000 度/秒。由于高凝固速率和高压下机械压实的结合，获得了具有精细结构和高密度的组成为Al ₈₆ Ni ₆ Co ₄ Gd ₂ Tb _{2的合金样品。}在 5–7 GPa 的压力下，在合金中注意到新相的形成：Al ₃ (Gd/Tb)*（Al ₃U 型），具有原始立方体结构（cP 4/2），晶格参数a = 4.285 ± 0.002 Å，Al ₈ (Ni/Co) ₄ Gd*（Al ₈ Cr ₄ Gd 型）具有四方结构( tI 26/1) 参数a = 8.906 ± 0.003 Å 和c= 5.150 ± 0.003 埃。研究表明，由于固溶体和析出硬化，获得的样品的平均显微硬度很高（特别是在 7 GPa 的压力下）（~1700 MPa）。这几乎是原始样本的 2 倍。所获得的结果表明，在不改变其化学成分的情况下，通过改变结构和改变铝合金结构成分的组成，利用高压下熔体凝固的方法来改变工业用铝合金的性能水平是完全可能的。样本。