【摘要】 建立了一个模拟外应力作用下AZ31镁合金在高温退火过程中晶粒长大和织构演化的三维相场模型。通过3个欧拉角构成的欧拉空间表达晶体学取向,赋予有序化参数以晶体学取向的物理意义。由于镁合金晶体结构为密排六方结构,不同晶体学方向存在弹性各向异性,根据每个取向晶粒的(0001)面相对于外应力方向的角度旋转刚度矩阵,得到不同取向晶粒对应的刚度矩阵,从而计算出外应力对不同取向晶粒做的功。结果表明:将模拟结果与已有的实验结果进行了对比分析,织构模拟结果与实验观察到的织构相一致;外应力的增加会使晶粒长大速率加快,当外应力大于600 MPa时,可能会导致晶粒的异常长大;此外,当压应力大于400 MPa时,AZ31镁合金中会产生(0001)晶向平行于外应力方向的基面织构。更多还原

【Abstract】 A 3D phase-field model was established to investigate the effect of applied stress on grain growth and texture evolution in AZ31 magnesium alloy at elevated temperatures. The order parameters were given a physical meaning of lattice orientation of grains represented by three angles in spatial coordinates. The stiffness tensor for different grains was suggested different because of elastic anisotropy of the magnesium lattice by transforming the standard stiffness tensor with different degrees of the(0001) plane angle with respect to the direction of applied stress so that different grains contributed different amounts of work under applied stress. The results reveal that the simulation results are explained using the limited existing experimental data, and the texture results are in good agreement with the experimental observation. The grain-growth rate increases with the applied stress, which may lead to abnormal grain growth when the stress is greater than 600 MPa. Moreover, the applied stress will also result in an intensive texture of the (0001) axis parallel to the direction of compressive stress when the applied stress is greater than 400 MPa.更多还原