New MAX‐Phase Compounds in the V–Cr–Al–C System

Abstract

New layered compounds, (V 0.5 Cr 0.5 ) 3 AlC 2 , (V 0.5 Cr 0.5 ) 4 AlC 3 , and (V 0.5 Cr 0.5 ) 5 Al 2 C 3 were synthesized by reactive hot pressing V, Cr, Al, and graphite powders. The crystal structures of these new phases were determined using a combination of X‐ray diffraction and scanning transmission electron microscopy. (V 0.5 Cr 0.5 ) 3 AlC 2 is isotypical to Ti 3 AlC 2 ; while (V 0.5 Cr 0.5 ) 4 AlC 3 has the Ti 4 AlN 3 or α‐Ta 4 AlC 3 ‐type crystal structure. (V 0.5 Cr 0.5 ) 5 Al 2 C 3 is formed by periodically stacking of half‐unit cells of (V 0.5 Cr 0.5 ) 2 AlC and (V 0.5 Cr 0.5 ) 3 AlC 2 .