熱處理對高壓凝固Ti-48Al鈦鋁合金組織演變的影響Effect of heat treatment on microstructure evolution of Ti-48Al alloy solidified under high pressure

采用六面頂壓機制備2和4 GPa下高壓凝固試樣，并在真空封裝后進行1100 ℃保溫12 h空冷的高溫熱處理實驗，研究經(jīng)高壓凝固后Ti-48Al合金組織的演變規(guī)律以及高壓凝固后熱處理對Ti-48Al合金組織變化的影響。結果表明：經(jīng)高壓凝固后，隨著凝固壓力的增加，枝晶間γ相數(shù)量減少；當壓力到達4 GPa時，片層組織的體積分數(shù)約為99.31%。經(jīng)熱處理后，常壓凝固試樣變化不大，而高壓凝固試樣中均形成魏氏組織，采用1100 ℃爐冷熱處理和EBSD技術進行分析，確定了高壓下魏氏體組織的形成機制。

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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