Abstract
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)₂Al(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 α₂(Ti₃Al) + γ(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.

Key words
intermetallics, composites, MAX phases, microstructure, hardness

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