5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

Microstructures, growth orientation and the room temperature mechanical properties of Mg-14.61Gd alloy were investigated by using directional solidification technology and CAFE simulation method under G=30K/mm and v=10-200μm/s. The experimental alloys were mainly consisted of primary α-Mg phase and (α-Mg+Mg5Gd) eutectic phase under all the growth conditions, which is consistent with the calculated results by Scheil model. It was found that α-Mg primary phase presented unidirectional dendritic morphologies on longitudinal cross-section, the growth interface appearance of α-Mg changed from the protruding forward growth to the flat growth gradually and the dendritic arm spacing decreased gradually with the increasing v. When v increased from 10 μm/s to 100 μm/s, the main growth orientation of α-Mg changed from <11-20> and <10-10> to <11-20> , and the deviation angle ( θ ) from solidification heat flow direction reduced from 11.070° to 5.711°, the reason for this lied mainly in the change of the heat flux. Further increasing v up to 200 μm/s, the main growth direction of α-Mg was still in <11-20>, but the value of θ increased to 10.620°, and the anisotropy of the crystal was the dominant factor then. It was proved that the CAFE numerical simulation model could predict the grain structure and growth orientation reasonably for Mg-alloy. In addition, the intrinsic mechanism between microstructures, growth orientation and mechanical properties was also discussed. KEY WORDS Mg-Gd alloy, directional solidification, CAFE model, growth orientation, mechanical properties