Thermal Properties of Ni–Cr–Si–B–Fe Based Interlayer Material and Its Application in TLP Bonding of IN 718 Superalloy

Abstract

A new Ni–Cr–Si–B–Fe filler material is prepared for transient liquid-phase (TLP) bonding of Inconel 718 superalloy by mechanical alloying technique. The melting temperature range of the filler material and its activation energy of melting are determined by differential scanning calorimetry technique. The activation energy and melting temperature of the alloy powder decrease with increasing milling time. Inconel 718 alloy was joined via TLP by using the newly developed filler material. The effect of TLP bonding temperature and time on microstructural evolution and mechanical properties of the joint was investigated. Three distinct microstructural regions were observed in the bonding area: isothermal solidification zone consisting of a single-phase solid solution, diffusion affected zone consisting of extensive diffusion-induced precipitates of metallic boride, and unaffected base material. The ultimate shear strength and microhardness of the TLP-bonded joint increase with bonding time and temperature.