Crystallization process of an amorphous Sm 8Fe 85Si 2C 5 alloy under high pressure

Abstract

The crystallization process of amorphous Sm 8Fe 85Si 2C 5 alloy under a pressure of 4 GPa at a temperature of 923 K has been investigated. The high-pressure experiments were carried out in a belt-type pressure apparatus. Experimental results show that the crystalline phases in the annealed alloy consist of α-Fe phase and Sm 2(Fe, Si) 17C x . The grain size of the α-Fe phase and Sm 2(Fe, Si) 17C x in the alloy annealed for 20 min is 5.2 and 4.2 nm, respectively; and it increases slowly with annealing time. The volume fraction of both the α-Fe phase and Sm 2(Fe, Si) 17C x increases with increasing the annealing time. As the annealing time increases to 60 min, an α-Fe/Sm 2(Fe, Si) 17C x nanocomposite microstructure with a fine grain size, 8.8 nm for the α-Fe phase and 7.6 nm for the Sm 2(Fe, Si) 17C x , forms in the annealed alloy. The mechanism of crystallization of the amorphous Sm 8Fe 85Si 2C 5 alloy under high pressure is discussed. The α-Fe/Sm 2(Fe, Si) 17C x nanocomposite magnets prepared under 4 GPa have, compared with nanocomposite magnets prepared under normal pressure, an increase in both coercivity and remanent magnetization.