Microstructure and high-temperature mechanical properties of co-continuous (Ti3AlC2+ Al3Ti)/2024Al composite fabricated by pressureless infiltration

Abstract

Ti 3 AlC 2 /2024Al composites with a co-continuous structure were successfully fabricated from 2024Al powders and Ti 3 AlC 2 porous preforms (with porosity of 48%, 41% and 35%, respectively) by pressureless infiltration at 930 °C. Long-rod like Al 3 Ti was in situ formed due to reaction of Ti atoms de-intercalated from Ti 3 AlC 2 and liquid 2024Al, which interpenetrated with Ti 3 AlC 2 to form a new continuous framework. The mechanical properties in relationship with the initially different volume fractions of Ti 3 AlC 2 and 2024Al at room temperature and high temperature were investigated. At room temperature, 59 vol%Ti 3 AlC 2 /2024Al has the best comprehensive mechanical properties, with the flexural strength of 510 MPa, compressive strength of 729 MPa, and compressive strain of 5.49%. Due to the co-continuous structure and the excellent high temperature of Al 3 Ti, all samples exhibit well mechanical properties at 300 °C. Among them, 52 vol%Ti 3 AlC 2 /2024Al has the best performance with the ultimate compressive strength of 532 MPa, which is only 18.7% lower than room temperature. And even at 400 °C,it still has an objective compression strength of 394 MPa due to the highest content of Al 3 Ti. In addition, after quenching from 400 °C to room temperature, the residual flexural strength of 52 vol%Ti 3 AlC 2 /2024Al can be reached to 450 MPa with the mere reduction rate of 7.4%. And no cracks are observed at the boundary of each phase, which means the good thermal shock resistance of the composites.