Effects of Thermal Treatment on Structure of Fe-Co-Ni-Zr-B Glassy Alloy with a Large Supercooled-Liquid Region Studied by Mossbauer Spectroscopy

Abstract

Structural change in the supercooled-liquid region of Fe 58 Co 7 Ni 7 Zr 8 B 20 glassy alloy has been examined by Mossbauer spectroscopy Analyses of the Mossbauer spectra showed that the hyperfine field distribution patterns in quenched states from supercooled-liquid state differ from that in the as-melt-spun state. As the quenching temperature increases, the hyperfine field distribution tends to show several peaks some of whose hyperfine field values seem to correspond well to those in crystalline Fe, Fe 3 B, Fe 2 B and Fe 2 Zr, although these distribution peaks are quite broad. These results as well as the initial crystallization behavior indicate that the thermal treatment in the supercooled-liquid region causes a compositional short-range order. It is, however, supposed that the chemical bond strengths are competitive among the Fe 3 B-Fe 2 B-, FeZr 2 - and Fe-Zr-B-type compositional short-range order, and their growth frustrate each other in the supercooled-liquid region. This competitive frustration should be one of the reasons for the thermal stability against crystallization that occurs in the glassy alloys with a large supercooled-liquid region.