Simulation of Grain Growing Process of Zinc-Aluminium Alloy under High Pressure

Abstract

Under high pressure of more than 1GPa, the grain growing process of Zinc-Aluminium (ZA) alloy is difficult observed by experimental method, therefore numerical simulation method is used to observe grain growing process of ZA alloy. Pressure as a important variable is leading-in thermodynamic parameters of ZA alloy, then solute diffusion and redistribution model, grain nucleating and growing model are present, and dendrite growth module is applied to describe grain growth. The simulation results of grain growth process under high pressure are demonstrated: In the initially solidification stage, grains are equiaxed growing process, after 15s solidification time, dendrite arm size are not equal, the reason is there are nonhomogeneous temperature fields around grains, which make some grains appear fast growing velocity, even it can be observed that dendrite arm of different grains are meet each other at 25s solidification time. Comparing simulated microstructure with experimental microstructure under 2GPa high pressure, it shows both grain size and grain distribution are similar, proving that the grain growing process can be well observed by simulation method.