Effect of short-range order in liquid on the glass forming ability of Fe-Si-B alloy wires

摘要

The effect of short-range order (SRO) in liquid on the glass forming ability (GFA) has been investigated in Fe_(100-(x + y))Si_xB_y (2.5 <= x <= 22.5, 2.5 <=y <=25, 10 <=x +y <= 35) alloy wires. We have considered a thermodynamic condition in which a liquid phase can be stated in terms of SRO and introduced a new approach to estimate the degree of SRO in liquid. Experimental investigations into the GFA of the Fe-Si-B alloy wires were preformed and compared with the results of thermodynamic approach to make the relationship between the SRO in liquid and the GFA of the Fe-Si-B alloy clear. It is demonstrated that SRO in liquid represented in terms of DELTA H~(mix) + RT_m is not the enough condition but necessary one for the formation of an amorphous phase. The GFA of the alloy increased with the increasing SRO in liquid, then decreased with that after showing a maximum. Amorphous wires could not be obtained when the degree of SRO was very large. It is believed that the GFA of the alloy wires depends on whether the given degree of SRO in liquid prefers vitrification or transformation into a crystal.