Synthesis of 312 phases and composites thereof

A process for forming a substantially single phase product comprising M.sub.3 Si.sub.1 Z.sub.2 phase wherein M is at least one transition metal and Z is at least one of B, C and N, said process comprising the steps:

• (a) forming a mixture of (i) transition metal species, (ii) silicon carbide, and (iii) non-metal species selected from the group consisting of boron species, carbon species and nitrogen species, said mixture being a powder comprising not more than about 80 weight percent M.sub.3 Si.sub.1 Z.sub.2 ;
• (b) heating said mixture to a temperature of about 1000.degree. C. to about 1800.degree. C. at substantially atmospheric pressure for a time sufficient to form M.sub.3 Si.sub.1 Z.sub.2.

A process for forming a substantially single phase product comprising an M.sub.3 X.sub.1 Z.sub.2 phase wherein (i) M is at least one transition metal, (ii) X is Si, and (iii) Z is C, said process comprising the steps:

• (a) forming a mixture of (i) transition metal species, (ii) silicon species and (iii) carbon species selected from the group consisting of graphite, carbon black, charcoal, coke, non-transition metal carbide and transition metal carbide;
• said mixture being a powder comprising not more than about 80 weight percent M.sub.3 X.sub.1 Z.sub.2 ;
• (b) reactive hot pressing said mixture at a temperature of about 1000.degree. C. to about 1800.degree. C. under apressure of about 5 MPa to about 200 MPa for atime sufficient to form M.sub.3 X.sub.1 Z.sub.2 phase.