Presentation Information
[P1-59]Temperature field variations during directional solidification of rare-earth large-size Tb-Dy-Fe magnetostrictive materials and their effect on growth orientation
*jiang ping xin1, Jiheng Li1, Xiaoqian Bao1, Xuexu Gao1 (1. USTB (China))
Keywords:
magnetostriction,directed solidification,orientation,twinned crystals
Tb-Dy-Fe super magnetostrictive alloys are strongly anisotropic in magnetostrictive properties. The preparation of Tb-Dy-Fe alloys with highly axial selective orientation and high performance is of great research significance. Large-size Tb-Dy-Fe<110> oriented rod crystal materials are prepared by directional solidification technique. The temperature field derived from the finite volume method simulating the heat transfer during the directional solidification process shows that the temperature gradient at the solid-liquid interface front gradually decreases with the crystal growth, and the morphology of the mushy zone is transformed from a planar state to a concave state. The experiments show that as crystal growth proceeds, the grains grow along the heat flow direction, the main growth orientation is concentrated near the <110> direction, and the grains acquire the same organization as the direction of the easy magnetization axis through competitive growth, and the concentration of the <110> orientation decreases in the later stages of grain growth. On the one hand, the distribution of the temperature field in the late stage of directional solidification makes the state of the crystal growth front become concave, and there is an angle between the crystal growth direction and the axial direction; on the other hand, the reduction of the temperature gradient makes the supercooling degree of the grain growth front increase, and the increase of supercooling degree causes the change of the atomic stacking mode in the process of crystal growth, which is conducive to the creation of twins, and the creation of twins causes the crystal growth orientation to be changed. The twinning will change the orientation of the crystal growth.