热处理对高压凝固Ti-48Al钛铝合金组织演变的影响Effect of heat treatment on microstructure evolution of Ti-48Al alloy solidified under high pressure

采用六面顶压机制备2和4 GPa下高压凝固试样，并在真空封装后进行1100 ℃保温12 h空冷的高温热处理实验，研究经高压凝固后Ti-48Al合金组织的演变规律以及高压凝固后热处理对Ti-48Al合金组织变化的影响。结果表明：经高压凝固后，随着凝固压力的增加，枝晶间γ相数量减少；当压力到达4 GPa时，片层组织的体积分数约为99.31%。经热处理后，常压凝固试样变化不大，而高压凝固试样中均形成魏氏组织，采用1100 ℃炉冷热处理和EBSD技术进行分析，确定了高压下魏氏体组织的形成机制。

High pressure solidification samples were prepared at 2 and 4 GPa on a HTDS-032F type cubic hydraulic pressure machine. Then, the samples were heat-treated at 1120 ℃ for 12 h. The effect of high pressure on the microstructure evolution of Ti-48Al alloy solidified under high pressure and heat treatment on the microstructure evolution of Ti-48Al alloy solidified under different pressures were investigated. The results indicate that, when solidified under high pressure, the γ-segregate phase decreases with increasing the pressure. When the pressure reaches 4 GPa, the volume fraction of lamellar structure is about 99.31%. After heat treatment, the microstructure solidified under normal pressure is not changed, but Widmanst？tten lamellar microstructure forms in high pressure solidified samples by NAKA mechanism, which is confirmed by heat treatment and EBSD analysis.

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