The mechanism of grain growth and thermal stability in Ni-1 at.% Pb alloy

The effect of undercooling and subsequent annealing on the evolution of grain growth of Ni-1 at.% Pb alloy was investigated with the help of glass fluxing technique and isothermal annealing process. To investigate the mechanism of grain growth, isothermal annealing processes of the as-quenched samples at different undercoolings were conducted at different annealing temperatures. The whole process of grain size evolution could be rationally categorized as three stages: 1. The slow growth stage; 2. The rapid growth stage; 3. The stable growth stage. With the utilization of grain boundary energy σb model, it is shown that the stability in stage 1 is due to the reduction of σb. As a result of second phase precipitation occurring at 2-3 stages, rapid grain growth occurs.