Stability of V2AlC with Al in 800-1000 °C temperature range and in situ synthesis of V2AlC/Al composites

The unique properties of the MAX phases make them a desirable reinforcement material in metal matrix composites. The promising results of MAX reinforced Mg matrix composites have spurred interest in developing Al-MAX composites with comparable or better properties. Herein, two-phase Al-V2AlC composites were synthesized from elemental powders. The nominal compositions were chosen so that in situ reactions would produce either a 75/25 vol. % Al/V2AlC or a 50/50 vol. % Al/V2AlC composites. Elemental powders were heated to 1000 °C and reacted for 0.5, 2.5 or 10 h under flowing Ar. Water quenched samples from temperature >950 °C produced two-phase Al-V2AlC composites; furnace cooled samples did not. X-ray diffraction, scanning electron microscopy and differential scanning calorimetry were used to investigate the stability of V2AlC with Al in the 800-1000 °C range. The Al-V-C phase diagram was defined in the Al-rich corner. At 800 °C, the Al and V2AlC phases were found to be in equilibrium with both Al3V and Al4C3, but not with each other. This study is a requisite step for the development of advanced composites in the Al-V-C system.