Effect Of TEMHD On The Microstructure Of Directionally Solidified Al Alloy

A horizontal Bridgman directional solidification configuration is designed on the basis of Bridgman directional solidification configuration. Two alloys Al-4%Cu and Al-11%Si are solidified directionally using this configuration under a transverse direct current steady-state magnetic field. Effect of TEMHD on the microstructure of directionally solidified Al alloy is discussed. Tow velocity R equals to 20μm/s,50μm/s,100μm/s,200μm/s respectively. With the change of intensity of magnetic field(B) from 0 T to 0.3 T, microstructure of Al-4%Cu alloy becomes coarse and prime dendrite arm spacing(PDAS) and secondary dendrite arm spacing(SDAS) increase; Spacing between eutectic Si flakes of Al-11%Si alloy increase and Si flakes become coarse. However, microstructure of Al-4%Cu and Al-11%Si alloys becomes fine as the tow velocity increases when B keeps stable. The effect of magnetic field on the microstructure is analyzed by mathematic models of thermo current in mushy zone.