外加应变对Ti-25Al-10Nb合金显微组织影响的相场法模拟

SIMULATION OF EFFECT OF APPLIED STRAIN ON THE MICROSTRUCTURE OF Ti-25Al-10Nb ALLOY BY PHASE FIELD METHOD

利用相场法研究了外加应变场对Ti-25Al-10Nb合金中α2→O相变组织的影响．研究表明,除了外加应变的大小之外,外加应变方向对O相析出组织也有明显影响．模拟得出,外加应变方向对O相体积分数的影响可达24％,外应变大小对 O相体积分数的影响可达60％．当沿着α2相的<21-10->方向施加单轴压应变且应变量εamp大于0．5εs(相变应变量)时,合金会形成α2+O相的全片层显微组织,有望显著改善合金的性能．

The effect of applied strains field on the microstructure evolution during α2 phase to O-phase （orthorhombic phase） transformation in Ti-25Al-10Nb alloy is studied by computer simulation using a phase field model. It is shown that not only the applied strain magnitude but also the applied strain direction affects the microstructure significantly. The effect of strain direction on the volume fraction of O-phase is up to 24% but strain magnitude up to 60%. The fully lamellar microstructure can be formed in Ti-25Al-10Nb alloy when the compress strain is loaded along （2110） of α2 phase and has a magnitude ε^amp greater than 0.5 εs, where εs is a strain corresponding to the stress-free transformation.