Reaction mechanism and microstructure evolution of superhigh strength in-situ TiC/Ti composite based on Cr2AlC-Ti system

In the field of exploring the precursors of TiC/Ti composite, Cr2AlC was innovatively used as the precursor in this study. Based on the formation of TiC in pure Ti matrix during hot-pressing sintering, Al and Cr elements changed the microstructure of matrix to form TiC/(& alpha; + & beta;)-Ti composite, and the reaction mechanism of Cr2AlC-Ti system in the sintering process was discussed in detail. During the cooling process, Cr element retained & beta;-Ti to room temperature, and the uniformly distributed TiC was used as the nucleation site of & alpha;-Ti. By controlling the content of Cr2AlC added, the microstructure of the composite was regulated. In 10 vol% Cr2AlC/Ti composite, the & alpha;-Ti extend form the boundary of TiC to all sides, forming a microstructure of quasi-continuous network structure covering equiaxed & beta;-Ti, which exhibited the optimal strength with ultimate tensile strength of 1184 MPa. The interface analysis shown that there is good interface bonding at TiC/& alpha;-Ti, which made the whole frame have good load transfer. And there were stacking faults at the TiC/& beta;-Ti interface, meaning the obvious CTE mismatch strengthening at it.

Automated summary

In this study, Cr2AlC was used as the precursor for TiC/Ti composite, and the formation mechanism of TiC/α+β-Ti in the sintering process was discussed. By controlling the amount of Cr2AlC added, the microstructure of the composite could be regulated. The resulting composite with 10 vol% Cr2AlC exhibited the optimal strength with good load transfer at the TiC/α-Ti interface and CTE mismatch strengthening at the TiC/β-Ti interface.