Significant improvement in tensile properties of an advanced PM Ni based superalloy joint by HIP treatment

• Hot isostatic pressing eliminated weakly bonded area and microvoid at interface. • Hot isostatic pressing promoted migration of grain boundaries at the interface. • Dislocation density at the interface was decreased by hot isostatic pressing. • Tensile properties of the bonded joints were improved by hot isostatic pressing. Tensile properties of an advanced powder metallurgy (PM) Ni based superalloy diffusion bonded joints were significantly improved by hot isostatic pressing (HIP) and the improvement mechanism was studied. Results showed that HIP treatment eliminated the weakly bonded areas and microvoids at the interface. In addition, HIP treatment also significantly promoted the migration of grain boundaries and decreased the dislocation density at the interface. After HIP treatment, the ultimate tensile strength of the joint bonded using a 2-μm-thick Ni coating reached 98.63% of the base alloy following the same thermal cycle.