Characterization of intermetallic bonded TiC composites prepared by mechanically induced self-sustained reaction

Abstract

The microstructure and mechanical properties of Ni3Al bonded TiC composites prepared by mechanically induced self-sustained reaction (MSR) were investigated. Ultrafine TiC–Ni3Al composite powders with various binder contents were synthesized by high energy ball milling of Ti–C–Ni–Al powder mixtures. Some porous blocks, which consisted of spherical TiC grains and Ni3Al binder, were also formed in each system after MSR. A core-rim structure present in the grains of the sintered TiC–Ni3Al composites was observed by Scanning Transmission Electron Microscopy (STEM). TiC particles dissolved selectively and then precipitated along with a stable crystal plane and gradually evolved into a faceted octahedron in the 3D space, which led to the formation of sharp-edged ceramic grains. High Resolution Transmission Electron Microscopy (HRTEM) analysis showed a 1–2nm width transition zone and a low-angle misorientation between the ceramic phase and the binder phase. The TiC particles that precipitated from Ni3Al during MSR were easily wetted by the liquid Ni3Al binder, which gave rise to the superior mechanical properties of the TiC–Ni3Al composites.