MAX phase – Alumina composites via exchange reaction in the Mn+1AlCn systems (M=Ti, V, Cr, Nb, or Ta)

• Ten Mn+1AlCn phases were produced from M-oxides via a single step exchange reaction.
• Eight of these MAX phases had not been produced via this method before.
• Al was found to be a suitable reducing agent in all cases.
• The process was also discovered to work under SHS and MASHS conditions.

MAX phases have been produced for the first time via an exchange reaction between the M-element oxide and Al leading to an M–Al–C–Al2O3 composite in the V–Al–C, Cr–Al–C, Nb–Al–C and Ta–Al–C systems in addition to the previously known Ti–Al–C system. The reduction reaction was first investigated by forming the binary M–X carbide and then proven to be generic across all M–Al–C systems with the production of the M2AlC phase in each case. The work was extended to the other M3AlC2 and M4AlC3 phases in the respective systems, and was successful in 4 of the 5 cases with moderate yield.

A range of Mn+1AXn phases (M-octahedra with X centres and A layers) were synthesised directly from the M oxide via exchange reactions for the 5 M-elements shown.Figure optionsDownload as PowerPoint slide