Synthesis and sintering of MAX phases in the Zr–Al–C system

Abstract In this paper, synthesis and sintering of MAX phases in the Zr–Al–C system is described. Different mixtures of initial Zr/Al/C and Zr/Al/ZrC powders were used to synthesize the MAX phases of Zr 2 AlC and Zr 3 AlC 2 compositions by a combined method (high‐temperature sintering followed by spark plasma sintering [SPS]). The highest content of the Zr 3 AlC 2 MAX‐phase was obtained using initial Zr/Al/ZrC powders in a component ratio of 1:1.5:2—51.1 vol.%. The optimal temperature for the synthesis of a material based on the Zr 2 AlC MAX phase is 1525°C, and a material based on Zr 3 AlC 2 is 1575°C. During subsequent SPS at a temperature of 1500°C, a pressure of 50 MPa, within 5 min, it was obtained a material containing up to 71.1 vol.% Zr 3 AlC 2 . The relative density of the samples synthesized and consolidated by the SPS method reaches 98.9%. The structure of the obtained synthesized MAX materials includes elongated grains of the composition Zr 2 AlC and Zr 3 AlC 2 , which determines their high strength. The influence of the sintering time and temperature on the formation of the MAX phase of Zr 3 AlC 2 from the initial powders of Zr/Al/ZrC is shown. Zirconium carbide, as an intermediate phase, is always present in the final products. Due to the large evaporation of aluminum, the ZrAl 2 phase is also present in the synthesis products. An excess of aluminum contributes to the greatest formation of the Zr 2 AlC and Zr 3 AlC 2 phases during the combined synthesis.