Fe-Zr AMORPHOUS ALLOYS FOR MAGNETIC REFRIGERANTS NEAR ROOM TEMPERATURE.

Abstract

(Fe//1// minus //xNi//x)//9//0Zr//1//0(x equals 0, 0. 01, 0. 02 and 0. 03) and Fe//0//. //9//5M//0//. //0//5)//9//0Zr//1//0(M equals Al, Si, Ga, Ge and Sn) alloys were prepared by a single roll-quenching and piston anvil-quenching. The Curie temperature T//c, saturation magnetization M//s and magnetic entropy DELTA S//M have been investigated. The values of T//c increase from 240 K to near room temperature with increasing x up to 0. 05, tending to increase with increasing atomic number of the elements M. The values of DELTA S//M as well as M//s increase with increasing x, and DELTA S//M increases in proportion to the magnetic field H. The maximum magnetic entropy ( DELTA S//M)//M//a//x of 13 kJ multiplied by (times) m** minus **3 multiplied by (times) K** minus **1 near T//c at H up to 1. 12 MA multiplied by (times) m** minus **1 is about 50% smaller than that of Gd. However, the change in DELTA S//M with temperature T is smaller. The curves of DELTA S//M-T cannot be approximated by a molecular field theory.