The effects of neutron irradiation on the microhardness of nickel and a nickel-carbon solid solution

The present research and discussion indicates that: 1. The large drop in microhardness observed in supersaturated nickel-carbon solid solutions observed after annealing above about 3000C is due to the formation of Ni3C or graphite. 2. The decomposition of the supersaturated nickel-carbon solid solution is enhanced by neutron irradiation. This enhancement appears to primarily be a result of carbon vacancy interactions which may assist the nucleation of Ni3C or graphite precipitates. 3. Neutron irradiation appears to change the form and stability of the precipitates or carbon-vacancy traps at high annealing temperatures (T > 5000C). 4. The increase in microhardness of nickel observed in irradiated nickel is attributed to the presence of vacancy type defects which are removed by annealing at temperatures of 350 to 6000C. (orig.)