Precipitation Behavior in Fe–Mn–Cu Austenitic Alloys

Abstract

The precipitation behavior in Fe–Mn–Cu austenitic alloys was studied by means of the hardness test, electric resistivity measurement, Mössbauer effect measurement, and optical and transmission electron microscopy. The main results obtained are as follows: In Fe–Mn–3Cu, Fe–Mn–5Cu and Fe–Mn–7Cu alloys, an age-hardening phenomenon was observed and the degree of hardening, became remarkable with increase in Cu content. In this alloy system, a two-phase decomposition was expected to occur and it was considered to be based on a miscibility gap in the Fe0.5 Mn0.5–Cu quasi-binary system. Namely, it was suggested that these Fe–Mn–Cu alloys were decomposed into a Fe–Mn rich (Cu-poor) phase and a Cu-rich phase. By means of splat-quenching from the liquid state an austenitic single phase of Fe–Mn–40Cu alloy was obtained and the two-phase decomposition was also expected to occur in this alloy.