Low-oxygen Ti₃AlC₂ MAX powder deoxidized by Ca reductant: Comparison of contact and noncontact deoxidation mechanism

This study investigates the decrease in oxygen concentration caused by the removal of α-Al₂O₃ inclusions in Ti₃AlC₂ MAX powder. The Ti₃AlC₂ MAX powder was deoxidized in the solid-state using calcium (Ca) as the reductant under contact and noncontact conditions. The oxygen concentration was decreased by removing the α-Al₂O₃ inclusions in Ti₃AlC₂ MAX powder through Ca contact and non-contact deoxidation. In the α-Al₂O₃ reduction reaction, Al diffusion and excess Ca interactions led to the formation of a Ti₂AlC phase, which was suppressed by reducing amount of Ca used. Oxygen reduction without any phase change was possible through contact deoxidation at 750 °C for 5 h. The oxygen concentration of deoxidized MAX powder was 9,450 ppm. In the case of noncontact deoxidation, the Ti₂AlC phase was suppressed by reducing the amount of Ca used to 0.5 g. The oxygen concentration of the deoxidized MAX powder was 3,400 ppm.