Effects of C and N additions on primary MAX phase particles in intermetallic Ti-Al-Nb-Mo matrix in-situ composites prepared by vacuum induction melting

The effects of C and N additions on primary MAX phase particles were studied in in-situ intermetallic matrix composites with nominal composition Ti-37Al-3.8Nb-1Mo-0.1B-xC-yN (at.%), where x + y = 5 at.%. The in-situ composites were prepared by vacuum induction melting and solidification in graphite crucibles. The increasing content of N in the studied in-situ composites decreases the solubility of Nb in the primary (Ti,Nb)(2)Al(C,N) MAX phase particles and leads to a partial substitution of C by N in them at the expense of increasing content of N in lamellar alpha(2)(Ti3Al) + gamma(TiAl) matrix. The shape factor increases and volume fraction and size of the MAX phase particles decrease with increasing content of N. The increasing content of N in the composites has no significant effect on nanohardness of the primary particles but increases their elastic modulus.