Improved hot workability of TiAl composite with core-shell structure via in-situ synthesized multi-phases ceramic particles

Abstract

TiAl composite with core-shell structure was in-situ synthesized incorporating BN nanosheets and graphene oxide into TiAl alloy using SPS, and the hot deformation behaviors were subsequently investigated on a Gleeble-1500D thermal simulation machine. The microstructural evolution and the influence of ceramic particles on hot deformation were revealed using OM, SEM, TEM, and EBSD. The results demonstrated a refined microstructure of TiAl composite induced by ceramic particles providing extra nucleation sites for DRX, contributing to lower flow stress, with peak stresses of 387 and 360 MPa for TiAl alloy and TiAl composite deformed at 1200 °C/1s, respectively. Moreover, dislocation slip was inhibited by ceramic particles leading to dislocation pile-up, facilitating the nucleation and growth of DRX at lamellar colony boundaries and α/γ interfaces. Notably, the “shell” composed of TiB and TiAlN nanoparticles coordinated the deformation of lamellar colonies with different orientations, improving the hot workability of TiAl composite.