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

Abstract

AbstractIn 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 Zr2AlC and Zr3AlC2 compositions by a combined method (high‐temperature sintering followed by spark plasma sintering [SPS]). The highest content of the Zr3AlC2 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 Zr2AlC MAX phase is 1525°C, and a material based on Zr3AlC2 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.% Zr3AlC2. 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 Zr2AlC and Zr3AlC2, which determines their high strength. The influence of the sintering time and temperature on the formation of the MAX phase of Zr3AlC2 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 ZrAl2 phase is also present in the synthesis products. An excess of aluminum contributes to the greatest formation of the Zr2AlC and Zr3AlC2 phases during the combined synthesis.