Analysis of hot ductility of Ni-Cr-Al alloy

The thermal tensile test of cast Ni-Cr-Al alloy within the temperature range of 950-1 200 ℃ and strain rate of 0.25 s^-1 was conducted by using Gleeble-3800 thermal simulation test machine, and the evolution law of hot ductility was analyzed by combining fracture morphology and microstructure. The results show that tensile strength decreases with the increase in the temperature, and reduction of area increases first and then decreases. The reduction of area at the temperature range of 1 000-1 150 ℃ is more than 75%, which shows excellent hot ductility. The microstructure shows that the ductility is poor at 950 ℃ due to low temperature, the ductility is improved with the increase in the temperature, and the formation of recrystallized organization is conducive to ductility enhancement at 1 050-1 150 ℃. However, the ductility deteriorated drastically at 1 200 ℃, which was attributed to the segregation of P and Zr elements at grain boundaries, leading to the weakened grain boundaries and the initiation of intergranular cracks.