Microstructure and properties of TiCx/TC4 composites with a quasi-network structure prepared by the decomposition of the Ti2AlC precursor

In the present study, a novel titanium matrix composite with a quasi-network structure was successfully fabricated via the hot-press sintering of the TC4 powder and Ti2AlC precursor at 1200 degrees C and 25 MPa. To explore the effect of the Ti2AlC content on the microstructure and properties of the prepared composites, 1-8 vol% Ti2AlC was selected as the representative samples. Microstructural analysis showed that the initial Ti2AlC was transformed into TiCx, and Al atoms diffused into the TC4 matrix to form a Ti(Al) solid solution. The alpha ->beta transformation temperature of Ti decreased based on thermal analysis. After increasing the amount of Ti2AlC, the alpha phase gradually shifted to equiaxed grains, and the grain size decreased, while the alpha/beta ratio changed. When the content of Ti2AlC was 3 vol%, the composite's strength significantly improved, with smaller ductility loss and a tensile yield strength of 939 MPa, tensile ultimate strength of 1007 MPa, compressive yield strength of 1292 MPa, and compressive ultimate strength of 2041 MPa. This strength improvement was attributed to fine-grain strengthening, solid-solution strengthening and second-phase strengthening. Moreover, theoretical calculations indicated that the solid-solution strengthening dominated the improvement efficiency. (C) 2022 Elsevier B.V. All rights reserved.