Formation of sigma-like Mo-rich ternary phase in Fe sub 40 Ni sub 38 Mo sub 4 B sub 18 glass forming alloy

Studying conditions for bulk amorphous FeNiMoB elaboration, we obtained crystalline material with particular sigma-ternary precipitates. The Mo contents of this sigma phase varies from 52 at.% in (P) ingot sample to 58 at.% in (C) ingot sample. Lattice parameters are a: 9.39; c: 4.772 with some x-ray diffraction lines overlapped by reflections of (Fe,Ni) sub 3 B, (Fe,Ni) solid-state crystals. Annealing at 420 deg C during 5 h reduces Mo content in the precipitates to 45 at.%, indicating non-equilibrium as-cast-state structure illustrating the glass forming potentiality of the Fe sub 40 Ni sub 38 B sub 18 Mo sub 4 composition. The intermetallic sigma phase is likely formed by overheating nuclei in the melt, grown by fast diffusion under cooling conditions related to each mould shape. Additional annealing treatments are being investigated to follow structural transformations of this intermetallic-ternary-sigma phase.