Effect of the Solidification Mode on the Pore Growth of Gasar Porous Mg-3 Wt.% Ag Alloy

Lotus-porous Mg-3 wt.% Ag alloy was prepared by directional solidification. The pore structure was related to the solidification mode of the alloy. The pores grew stably under the solidification conditions of planar, cellular, and columnar dendrites but not under the solidification condition of equiaxed dendrites. The numerical simulation shows that the solidification rate and temperature gradient decrease rapidly with an increase in the solidification height, but their ratio remains unchanged. During the solidification process, the solidification mode of the alloy changed from cellular dendrites to columnar dendrites, and finally to equiaxed dendrites. The calculated results of the solidification mode transition are consistent with the solidification structures of the Mg-Ag alloy at different heights.