Magnetic and structural monitoring of nanophase precipitation during ageing of water-atomised Cu–5% Co alloy powders Original Research Article

A Cu–Co alloy powder was produced by water atomisation and a powder fraction was subsequently consolidated by hot isostatic pressing. The precipitation behaviour in this rapidly solidified Cu–Co alloy powder was investigated by a combination of magnetic measurements, X-ray diffraction, transmission electron microscopy structural studies and microhardness measurements. The magnetic measurements are a sensitive technique for monitoring the early stages of precipitation from the supersaturated solid solution produced by rapid solidification. Small cobalt clusters were detected already in the as-atomised powder. The hardening observed for the low-temperature heat treatments (up to peak hardness) is correlated with the precipitate sizes derived from magnetic measurements, allowing a rationalisation of the observed hardening in terms of coherency strengthening.