COMPOSITIONAL CORRELATIONS IN THE THERMAL-STABILITY OF AMORPHOUS IRON RARE-EARTH-METAL BORON ALLOYS

The thermal stability of iron-boron base amorphous Fe80-xRxB20 alloys (R=Ce,Nd,Sm,Gd,Tb,Dy,Er; x=0,2, 6,10,20 mol%) has been investigated by calorimetry (DSC). It has been found that the crystallization temperature (Tcr) increases to the maximum with increasing concentration of the rare earth metal (x) up to x=6 with R=Ce, Nd, and Sm, and up to x=10 with R=Gd,Tb,Dy and Er. Further, it has been found that Tcr increases in proportion to the melting temperature of the rare earth metal (TM(R)) for x=2, or the melting temperature of the intermetallic compound RB4 (TM(RB4)) for x=6. In the case of x=6, 10 and 20, Tcr vs. TM(R) plots and also in the case of x=20, Tcr vs. TM(Fe3R) plot break in two straight lines at the point for Gd. © 1990.