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Al-Zn-Mg合金在长时间的时效中存在双峰硬化现象,为了模拟析出硬化动力学,基于改进的Langer–Schwartz方法发展了不同析出物形成的双峰硬化模型。该物理模型考虑了Al-Zn-Mg合金在时效过程中新析出物的形核、生长、粗化,同时考虑了颗粒相互作用的2种机制(剪切和绕过)。将模型预测结果和实验结果进行了对比,结果表明两者吻合很好。系统和定量模拟研究结果表明:通过在生长方程中添加形函数,硬度曲线与测量值吻合;模型根据析出物的尺寸和体积分数定量评价该合金的力学性能;强化机制包括剪切和绕过2种机制,剪切机制向绕过机制的转变发生在颗粒生长的早期,而绕过机制是主要强化机制。
Al-Zn-Mg alloy has the phenomenon of bimodal hardening for a long time. In order to simulate the precipitation hardening kinetics, a bimodal hardening model of different precipitates was developed based on the improved Langer-Schwartz method. The physical model takes into account the nucleation, growth and coarsening of new precipitates of Al-Zn-Mg alloys during aging, taking into account the two mechanisms of particle interaction (shear and by-pass). The model predictions and experimental results are compared, the results show that the two agree well. The results of system and quantitative simulation show that the hardness curve is consistent with the measured value by adding the shape function in the growth equation. The model quantitatively evaluates the mechanical properties of the alloy according to the size and volume fraction of precipitates. The strengthening mechanism includes shearing and by-pass The mechanism of species shift from the shear mechanism to the bypass mechanism occurs early in particle growth, whereas bypass mechanism is the major reinforcement mechanism.