Mössbauer study of glassy alloys (Fe-Mo)80B20

Abstract

Glassy alloys of (Fe‐Mo)₈₀B₂₀, containing 2 to 4 at.% of Mo have been studied by ⁵⁷Fe Mössbauer spectroscopy. It is shown that a small amount of Mo included in the alloys has a pronounced effect in reducing the Curie temperature and in increasing the crystallization temperature, thereby making the glassy state more stable. The values of T_C=585 K, 535 K and 480 K have been determined for samples with 2, 2.4 and 4 at.% of Mo. At low temperatures, the effective hyperfine field shows a temperature dependence of H_eff(T) =H_eff(0)(1−BT^3/2...), due to spin wave excitations. The values of B= (28,35,39) ×10⁻⁶ K^−3/2 have been determined for these samples. However, all three samples share nearly the same value of B_3/2=B (T_C)^3/2 of about 0.4 The sample containing 2.4 at.% of Mo has a crystallization temperature of 760 K. Crystallization phases of (Fe‐Mo)₃B and (Fe‐Mo) alloys have been observed after crystallization.