Evidence of a coupling between magnetic and chemical interactions in FeV alloys: metallurgical aspects

The influence of magnetism on the short-range order (SRO) and its temperature dependence is clearly pointed out in a Fe 0.9 V 0.1 alloy. Emphasis is placed on the metallurgical aspects of the study carried out by means of residual resistivity and nuclear magnetic resonance (NMR) measurements at low temperature. The ordering kinetics were measured in order to determine the heat treatments required to obtain the thermodynamic equilibrium state for SRO and the appropriate conditions necessary to retain it at low temperature by quenching. The measured ordering rates are in good agreement with previous anelasticity results. The temperature dependence of the SRO below the Curie temperature T CM exhibits a strong departure from the behaviour expected in a classical mean-field approximation. This dependence is in qualitative agreement with that given by a magnetic mean-field model (Ising-Heisenberg). Preliminary results obtained at temperatures above T CM (1<T/T CM <1.4), in an Fe 0.96 V 0.04 alloy, exhibit the expected behaviour for the paramagnetic phase.