形变热处理对发动机用TiAl合金超塑性变形特性的影响

Effect of Thermomechanical Treatment on Superplastic Deformation Characteristics of TiA l Alloy Used in Engine

采用拉伸试验机等研究形变热处理对发动机用Ti Al合金超塑性性能和显微组织的影响。结果表明:超塑性变形处理后Ti Al合金等轴α相的平均晶粒尺寸约为1.5μm, Ti Al合金在900℃时达到最优的超塑性,其伸长率为1188%。其应力-应变曲线属于明显的应变软化曲线类型。超塑性变形处理后,Ti Al合金断口与夹头区域的显微组织发生粗化作用,合金基体中的α晶粒内及其晶界部位形成了众多位错结构,其晶粒依然维持着良好的等轴形态。

The effects of thermomechanical treatment on microscopic structure and superplastic performance of TiAl alloy used in engine were researched by the tensile test, etc. The results show that, the average grain size of the equiaxed a phase of TiAl alloy is about 1.5 μm after the superplastic deformation processing, TiAl alloy can achieve optimal superplastic performance at 900℃, the elongation is 1188%. The stress-strain curve belongs to apparent strain softening curve type. The coarsening of the microstructure in fracture and chuck area of TiAl alloy appears. Many dislocations are formed in the a grain and the grain boundary in the alloy matrix, its grain still maintains a good equiaxial shape.