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本文建立了一个真实时空的相场模型模拟,研究了含不同尺寸和体积分数的球形第二相颗粒的纳米结构AZ31镁合金的晶粒生长过程;第二相颗粒对单相合金系统晶粒组织演化和生长动力学的影响;并将模拟结果与微米晶结构镁合金的模拟结果相比较.通过在自由能密度函数的表达式中增加第二相颗粒的表达来改进模型.模拟结果表明:纳米晶组织中第二相粒子对晶粒长大的钉扎作用,与对微米晶组织下的作用有很大区别.纳米结构中,第二相颗粒对晶粒长大影响存在一个粒子尺寸的临界值,当第二相颗粒体积分数为10%时,粒子尺寸的临界值为200 nm,随粒子含量增加,临界尺寸值将减小.另一方面,粒子含量越大对晶界钉扎作用越大,晶粒平均尺寸越小.该研究将为选择复合加入和原位合成的方法在AZ31镁合金中引入第二相颗粒的实验研究提供显微组织设计的理论指导.
In this paper, a real-time model of phase field model was established to simulate the grain growth of nanostructured AZ31 magnesium alloy with spherical second phase particles with different size and volume fraction. The second phase particles affected the grain structure of the single phase alloy system Evolution and growth kinetics.The simulation results are compared with the simulation results of micro-crystalline magnesium alloy.The model is improved by increasing the expression of the second-phase particles in the expression of free energy density function.The simulation results show that the nano-scale In the nanostructures, the influence of the second-phase particles on the grain growth is very different from the effect of the second-phase particles on the grain growth. Value, when the volume fraction of the second phase particles is 10%, the critical value of the particle size is 200 nm, the critical size value will decrease as the particle content increases.On the other hand, the larger the particle content, the more the pinning effect Large, the average grain size is smaller.The study will provide theoretical guidance for the microstructure design for the experimental study of the second phase particles introduced into the AZ31 magnesium alloy by the method of composite addition and in situ synthesis.