Simulation of dendritic growth of magnesium alloys with fluid flow

Abstract

A s the lightest known structural metals, magnesium alloys are treated as the green engineering materials of the 21st century due to their superior properties such as low density, high specific strength, excellent castability, good machinability and recyclability [1] . Magnesium alloys have been widely used in automotive, aerospace and 3C (computer, communication and consumer electronics) industries to replace steel, cast iron and even aluminum alloy. Such components and parts include steering wheels, gear boxes, notebook shells and mobile phone frames, etc. [2] . The performance of magnesium alloy parts is strongly influenced by the microstructure formed during solidification. Since the fluid flow has a significant impact on the structure formation of alloys during solidification [3] , and dendritic structure is probably the most commonly observed structure of magnesium alloys [4] , studying the effect of Abstract: Fluid flow has a significant impact on the microstructure evolution of alloys during solidification. Based on the previous work relating simulation of the dendritic growth of magnesium alloys with hcp (hexagonal closepacked) structure, an extension was made to the formerly established CA (cellular automaton) model with the purpose of studying the effect of fluid flow on the dendritic growth of magnesium alloys. The modified projection method was used to solve the transport equations of flow field. By coupling the flow field with the solute field, simulation results of equiaxed and columnar dendritic growth of magnesium alloys with fluid flow were achieved. The simulated results were quantitatively compared with those without fluid flow. Moreover, a comparison was also made between the present work and previous works conducted by others. It can be concluded that a deep understanding of the dendritic growth of magnesium alloys with fluid flow can be obtained by applying the present numerical model.