Effect of Nb addition on the microstructure and mechanical properties of additively manufactured Ti2AlC MAX-phase ceramic matrix composites

The Ti 2 AlC MAX-phase ceramic matrix composites were successfully additively manufactured from the Ti, Al, Nb and C elemental powders via laser powder bed fusion (LPBF) plus pressureless sintering (PLS) process. The phase formation, microstructure evolution , and mechanical properties of the as-fabricated samples were systematically analyzed under different Nb contents and sintering temperatures . The Nb content and sintering temperatures can significantly affect the phase formation and microstructure of samples. In the LPBF stage, all the samples are composed of TiC, Ti 3 Al, and TiAl, while adding Nb into the Ti-Al-C system powders can promote Ti 2 AlC MAX-phase. Furthermore, doping of Nb induce the transformation from Ti 2 AlC to Ti 3 AlC during the subsequent PLS. With increasing the sintering temperature from 1200 °C to 1400 °C, the width of Ti 2 AlC lamellar structure increases from 0.36 µm to 1.58 µm. The compressive strength of the Ti 2 AlC MAX-phase ceramic samples ranges between 17.5 MPa and 30.3 MPa. The optimal compressive strength of Ti 2 AlC MAX-phase ceramic matrix ceramic composite (30.3 MPa) was achieved under optimized Nb content (1 wt%) and sintering temperature (1300 °C). This work could shed light on designing Ti 2 AlC MAX-phase ceramic from the microalloying perspective via LPBF and sintering.