Ni60Ti40合金热压缩变形行为及机理

Thermocompression Deformation Behavior and Mechanism of Ni60Ti40 Alloy

对Ni60Ti40合金高温变形行为及变形机理进行了研究。通过计算获得了该合金在不同变形工艺下的应变速率敏感性指数m和变形激活能Q的变化规律,分别构建了Prasad、Gegel、Malas、Murty和Semiatin等不同失稳判据下的动态材料模型热加工图及包含位错数量的变形机理图。应用热加工图理论分析了该合金的适合成形加工区和流变失稳区,运用变形机理图预测了该合金高温变形过程中基于柏氏矢量补偿的晶粒尺寸和基于模量补偿的流变应力下的位错演变规律及高温变形机理。

The high-temperature deformation behavior of Ni60Ti40 alloy and the related mechanisms were investigated by thermocompression simulation experiments. The results of high-temperature compression tests were analyzed to reveal the effects of deformation temperature and strain rate on the structural properties and microstructure of alloys. Subsequently, the changing laws of the strain rate sensitivity index m, and the activation energy Q of alloys under different deformation conditions were obtained by calculation. Thermal processing maps based on the dynamic material model and the deformation mechanism maps revealing the dislocation quantity were plotted based on five plastic instability criteria, namely, Prasad, Gegel, Malas, Murty, and Semiatin, to analyze the physical significance of the parameters. The preferred forming zone and the rheological instability zone of the alloys were predicted using the thermal processing theories. The dislocation evolution laws and deformation mechanisms of the grain size with Burgers vector compensation were reported. With the aid of deformation maps, the rheological stress combined with modulus compensation during the high-temperature superplastic deformation was predicted.