EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

MXene phases are bi-dimensional carbide or nitride phases generally synthesized by ablation of lamellar MAX phases. As a broad range of compositions is known, the properties of both the MAX and MXene phases can be tuned.
Syntheses of M(Ti, Zr or Hf)2AlC (e.g. 211) MAX phases by pressureless sintering and Spark Plasma Sintering (SPS) from metallic powders and a carbon source have been carried out. The synthesis parameters have been optimized to increase the proportion of the desired phase in the samples.
Two-step cycles were used: a first dwell for the formation of intermetallic phases, which react during the second dwell at a higher temperature with the carbon-containing powder to form the MAX phase. With SPS, the effect of the temperature, holding time and load applied were studied. Using a pressureless cycle, a sample containing only Ti2AlC was obtained.
As applying a pressure during the thermal treatment seemed to not be beneficial to the formation of the MAX phase, synthesis was also performed by a reactive thermal treatment. Temperature, holding time and composition of the initial mixture were adjusted to reach more than 83 wt.% of the 211 phase.
Powders obtained by the two methods were sintered in an additional step. Density of the bulks was measured by Archimedes’ method.
Zr- and Hf- containing MAX phases were obtained by both techniques, although a greater amount of secondary phases were detected.