▎ 摘　　要

This paper reports a new casting strategy of titanium aluminum alloy: Si3N4-graphene core-shell nanoparticle (SGP) inoculant prepared by high-energy ball milling was added to Ti-46Al-4Nb alloy. The graphene and Si3N4 in the inoculant has an in-situ reaction with TiAl melt to form SiC and Ti2AlN particles. TiC@SiC core-shell structure can be observed in TiAl matrix, which indicates Si3N4 particles could be wrapped by graphene after milling treatment. Compared with matrix alloy, the microstructure of composite consists of full lamellar (FL) equiaxed grains. The grain size and lamellar spacing were significantly refined with the increase of inoculant content. Compression experiments were carried out at room temperature and high temperature respectively, and the results show that the specimens exhibit a compressive strength of 2.53 GPa with a strain about 16.0% in 273 K and 711 MPa in 1273 K. The increase of compressive strength may be related to the fine Si5C3 particles at the grain boundary. After that, the refining effect and the micromechanics model were discussed in detail.