淬火/回火热处理对TiAl基合金晶粒细化的影响

Effect of quenching temperature and tempering time on grain refinement in TiAl base alloy

研究了淬火/回火热处理中淬火温度和回火时间对Ti-48Al-2Cr-0.5Mo合金晶粒细化的影响。研究表明:一定的淬火/回火热处理能将大小约为1000μm的铸态组织细化成为18～30μm的均匀双态组织;TiAl基合金的细化效果严重依赖淬火阶段的加热温度,温度升高,得到的块状组织较细,羽毛状组织体积分数减少,在两相区回火时,高温淬火组织的回火组织较细,而时间的延长,晶粒长大,但不明显。

By tempering the quenching samples in the α+γ phase region, a very fine duplex microstructure (18-30 μm) was obtained in the as-cast Ti-48Al-2Cr-0.5Mo (at%) alloys with an initial grain size of about 1000 μm. The refining effect was greatly dependent on the quenched microstructure which was controlled by prior heating temperature. With the increase of the quenched temperature, the quenched microstructures become fine and the volume fraction of feather microstructure decreases. During tempering, larger grain was produced with time increasing. The 18 μm microstructure in tempering for 3 h obtained in the sample quenched at 1400°C. The grain refinement mechanism in TiAl base alloy was discussed theoretically.