Effect of magnetic field on metallurgical structure of magnetostrictive alloys solidified unidirectionally in microgravity

TbFe₂ alloy solidification experiments were conducted in a static magnetic field in microgravity using a 10 m drop tower. When TbFe₂ melt was solidified in a magnetic field from 0 to 0.12T in microgravity, a 111] crystallographic alignment dominated with an increased magnetic field, but the planar macrostructure was random. The magnetostrictive constant of TbFe₂ solidified in magnetic field of 0.12T in microgravity was 2000 ppm at the external 1. 6T magnetic field. When TbFe₂ melt was solidified unidirectionally in a 0. 1 T magnetic field in microgravity, a 111] crystallographic alignment dominated, and the planar structure grew and oriented along the solidification direction. The magnetostrictive constant of TbFe₂ solidified unidirectionally in a 0. 1 T magnetic field in microgravity was 4500 ppm at the external 1. 6T static magnetic field. For all solidification in normal gravity, the maximum magnetostrictive constant remained at 2000 ppm at the external 1. 6T static magnetic field. TbFe₂ crystals grew predominantly along the same direction as the magnetic field, and the planar structure oriented along the solidification direction in microgravity.