Growth of Co precipitates in irradiated dilute Ag-Co alloys

The growth of Co precipitates in dilute AgCo alloys under 1.8 MeV Kr ion irradiation was investigated by a combination of x-ray diffraction and magnetic measurements. For alloys with Co compositions ranging from 8 to 20 at. % precipitates grow in volume approximately linearly with dose, with no indication of saturation. The variation of temperature from liquid nitrogen temperature to 300 ° C had little effect on the growth behavior. Precipitation kinetics in these alloys is very different from that in dilute CuCo alloys, which showed steady state precipitate sizes at temperatures below 350 ° C . We attribute the different behavior to the low solubility of Co in liquid Ag (in contrast to its complete solubility in liquid Cu). The quantitative results suggest that the growth of Co precipitates is derived from particle aggregation rather than Ostwald ripening.