A RESISTOMETRIC STUDY OF PRECIPITATION-HARDENING IN Fe-0.5wt%Cu ALLO

Precipitation-hardening study was carried out on Fe - 0.5 wt% Cu alloy by measuring electrical resistivity and Vickers hardness at different ageing temperatures and for long ageing times. On ageing, it was observed that electrical resistivity initially rises with ageing time and then falls after very long ageing at a constant temperature. On the other hand hardness shows only small rise during early stages and rapid rise for further ageing. It may be inferred from XRD patterns, behavior of resistivity and / or hardness that the metastable Cu-rich clusters are formed at the earlier stages of the precipitation process causing only small changes in hardness but large rise in resistivity. These metastable Cu-clusters might have transformed to stable Cu-rich precipitates for long times causing further variations in hardness/ resistivity.