1997 Volume 38 Issue 3 Pages 189-196
The effect of Si additions on the thermal stability of the supercooled liquid before crystallization, glass-forming ability (GFA) and soft magnetic properties was examined for amorphous alloy series Fe72−xAl5Ga2P11C6B4Six, Fe72Al5−xGa2P11C6B4Six, Fe72Al5Ga2P11−xC6B4Six and Fe72Al5Ga2P11C6−xB4Six. The increases in the thermal stability and GFA and the improvement of soft magnetic properties were recognized in the replacements of P by 1 to 2 at%Si and of C by 1 at%Si. The supercooled liquid region (ΔTx) defined by the difference between crystallization temperature (Tx) and glass transition temperature (Tg) increases from 53 K for Fe72Al5Ga2P11C6B4 to 58 K for Fe72Al5Ga2P11C5B4Si1. The maximum thickness for glass formation (tmax) by copper mold casting increases from 1 mm for the Fe–Al–Ga–P–C–B alloy to 2 mm for the Fe72Al5Ga2P10C6B4Si1 alloy. The increases in ΔTx and tmax are presumably because of the increase in the degree of the satisfaction of the three empirical rules for the achievement of large glass-forming ability, i.e., (1) multicomponent alloy systems consisting of more than three elements, (2) significantly different atomic size ratios above about 12% and (3) negative heats of mixing. The soft magnetic properties are also improved by the replacement of 1 at%Si for P or C through the increase in the squareness ratio of B-H loop (Br⁄Bs) and the decrease in coercive force (Hc). The best soft magnetic properties for the bulk amorphous alloys are obtained for the Fe72Al5Ga2P10C6B4Si1 alloy and the saturation magnetization (Bs), Hc, Br⁄Bs, and Curie temperature are 1.14 T, 1.5 A/m, 0.45 and 594 K, respectively. The success of forming the Fe-based bulk amorphous alloys of 2 mm in thickness exhibiting the good soft magnetic properties is promising for future development as a new type of soft magnetic material.