Microstructure and Hardness Evolution of Solution Annealed Inconel 625/TiC Composite Processed by Laser Powder Bed Fusion

Abstract

This study deals with the Inconel 625 (IN625) alloy reinforced with micro-TiC particles processed by laser powder bed fusion. The microstructure and hardness in the as-built and solution-annealed states were investigated. The microstructures of the as-built IN625 and IN625/TiC states were primarily made up of columnar grains along the building direction. After the solution annealing at 1150 °C for 2 h, the IN625 alloy consisted of equiaxed grains due to recrystallization and grain growth. On the contrary, the solution-annealed IN625/TiC composite still presented columnar grains. Therefore, the TiC particles hinder the recrystallization, indicating higher microstructure stability for the composite. For the IN625/TiC composite, both the reduced alteration of the grains and the more intensive formation of carbides prevent a remarkable hardness reduction in the solution-annealed state.