Al-Cu合金近液相线铸造中组织演变的计算机模拟

Computer Simulation of Microstructure Evolution of Al-Cu Alloy in Near-Liquidus Casting

利用多尺度模拟方法针对Al-Cu合金近液相线半连续铸造的特点,建立了描述成形过程的温度场模型、液固相变模型,通过固相率变化将宏观尺度的温度场和介观尺度的微观组织模拟耦合起来,利用有限差分法和元胞自动机法对Cu质量分数分别为4%、4.5%及5%的Al-Cu合金近液相线铸造进行了组织演变的模拟。模拟了上述合金在浇铸温度为液相线温度以上7~25 K、铸造速度为1.5~3.5 mm/s、水冷系数为1 000~2 000 W/（m2.K）的液相线铸造中的组织演变,与ZL201合金的实验吻合。计算表明,当Al-Cu合金中Cu质量分数为5%、浇注温度为930 K、水冷系数为1 000 W/（m2.K）、铸造速度为2 mm/s时,获得的微观组织均匀、细小。

The models of temperature fields and phase transformation of Al-Cu alloy were developed for its near liquidus semi-continuous casting by a multi-scale simulation method,where the change in,solid fraction is available to couple the macro-scale simulation with meso-scale one.The solidifying process of Al-Cu alloys of Cu content of 4%,4.5% and 5% was simulated during near-liquidus casting at by using finite difference method and cellular automata method at pouring temperature of 7~25 K higher than liquidus temperature,casting speed of 1.5~3.5 mm/s and cooling coefficient of 1 000~2 000 W/（m2·K）.The result is consistent with experimental.the content of alloying elements has great influence on the semisolid microstructure formation.The calculation results showe that microstructure are fine,uniform and near globular when the mass fraction of Cu is 5%,pouring temperature is 930 K,cooling coefficient is 1 000 W/（m2·K） and casting speed is 2 mm/s.