Structural Changes in V-M(=Fe, Cu) Systems Induced by Mechanical Alloying

Abstract

BCC solid solution of Cu₃₀V₇₀ composition powders was produced by mechanical alloying(MA), although the solubility limit of solute Cu atom has been reported to be about 2 at% in the equilibrium Cu-V phase diagram. The neutron diffraction measurements, by taking a full advantage of a negligibly small scattering length of the V atom, allowed us to directly observe the evolution of the BCC structure phase composed of Cu atoms at the expense of FCC pure Cu.
MA of Fe₅₀V₅₀ composition powders produced an α-Fe₅₀V₅₀ solid solution instead of the σ-phase present at room temperature in the equilibrium Fe-V phase diagram. The α-Fe₅₀V₅₀ solid solution is a stable phase at high temperatures above 1200°C. Mechanical grinding(MG) of σ-FeV compound powders was carried out. The σ-FeV phase which possesses a tetragonal structure with 30 atoms in a unit cell was also transformed into the α-Fe₅₀V₅₀ solid solution of BCC structure after 120 hours of MG.