Effects of boron doping on the grain-growth kinetics and mechanical properties of γ/γ' nickel-aluminum alloys

The effects of 0.5 at. pet of boron doping on the microstructures and mechanical properties of gamma/gamma ' nickel-aluminum alloys have been investigated in the present study. A nickel-rich grain-boundary zone was observed in the boron-doped alloy after homogenization at 1 100 degreesC and prolonged annealing at 1200 degreesC. Boron doping also caused remarkable improvements in toughness and tensile elongation and caused the fracture mode to change from completely intergranular to completely transgranular. The grain growth following recrystallization at 1200 OC was found to be retarded upon boron doping. A sudden increase in tensile elongation and a sudden drop in hardness were also observed upon prolonged heating during isothermal annealing at 1200 "C. The results are interpreted with reference to boron-nickel cosegregation at the grain boundaries.