热处理对高压凝固Ti-48Al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, theγ-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.