LAUSR

Abstract Elastic modulus and hardness of Inconel 625/BNi-2 vacuum brazed joint microregion are investigated by the high temperature nanoindentation technique, and its microstructure is also inspected. The results show that the joint includes three parts of brazing seam, diffusion zone and metal substrate. Needle-like, granular-like and grain boundary shape precipitates distribute in the diffusion zone. The needle-like white precipitates are consisted of Cr–Mo rich borides, black granular-like precipitates are Cr-rich borides and the grain boundary shape precipitates are Mo-rich borides. Elastic modulus of the diffusion zone is larger than those of brazing seam and metal substrate under the same temperature. The tested elastic modulus decreases with increasing of the maximum press depth, while it increases with increasing of the applied loading rate. When the maximum press depth is larger than 800 nm or the applied loading rate higher than 10 mN/s, the elastic modulus of different regions keeps almost the same. For the hardness of the brazed joint micro-region, the value at high temperature is higher than those of at room temperature due to the existing of Ni3Al. The elastic modulus of brazed joint micro-region present linear relationship with the temperature and hardness.