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运用相场模型模拟了外加应力对NiTi形状记忆合金中Ni_4Ti_3沉淀相组织形貌及长大行为的影响.无外加应力作用的时效过程中,4组Ni_4Ti_3变体均沿着各自对应的(111)_(B2)惯习面从NiTi基体相中析出;而在〈111〉_(B2)方向施加压应力时,只有一组Ni_4Ti_3变体从NiTi基体相中析出,其惯习面法线方向平行于外加应力方向;单轴压应力作用下时效时,Ni_4Ti_3形核数量明显增加.外加单轴压应力可促进Ni_4Ti_3变体的形核和长大,但并不改变变体的面积分数、长度、宽度以及长度-宽度比等参数随时效时间变化的趋势;压应力增大使变体长度及宽度均略微增加,但均小于无应力作用下的情形;变体的面积分数随外加应力的增大而增加.相场模拟结果与实验观察结果吻合较好.
Phase phase model was used to simulate the effect of applied stress on the morphology and growth behavior of Ni_4Ti_3 precipitates in NiTi shape memory alloy. During the aging process without any additional stress, all the four Ni_4Ti_3 variants along the corresponding (111) When the compressive stress is applied in the direction of <111> _ (B2), only one group of Ni_4Ti_3 variants are precipitated from the NiTi matrix phase. The normal directions of the habit planes are parallel to each other In addition, the number of Ni_4Ti_3 nucleation increases obviously under the uniaxial compressive stress, and the uniaxial compressive stress can promote the nucleation and growth of Ni_4Ti_3 but does not change the area fraction, length, Width and length-to-width ratio and other parameters with the aging time trend; increasing the compressive stress so that the length and width of the variant are slightly increased, but were less than the case without stress; variant area fraction increases with the increase of external stress Increase.The phase field simulation results agree well with the experimental observations.