Melting diagram of cobalt-rich alloys in the system CCoNb

 

Chem. Met. Alloys 8 (2015) 83-90

 

Galina DMITRIEVA, Tetyana CHEREPOVA

 

The melting diagram of cobalt containing up to 3 wt.% C and 40 wt.% Nb was investigated and the liquidus and solidus projections were determined. Alloys were prepared by arc melting and cast from the liquid state. No ternary phases were found. The investigated part of the CCoNb phase diagram contains three isothermal three-phase planes, corresponding to the following four-phase invariant reactions with participation of liquid: L ↔ <Co> + NbC + C (1310), L ↔ NbC + <Co> + Co3Nb (1230), L + NbC + Co2Nb ↔ Co3Nb (1430). The eutectic temperature for the quasibinary system CoNbC was determined to be 142010C for an optimal niobium to carbon ratio of 9.5 (wt.%) in the carbide (NbC0.814).

 

іNb: ○ , □ , ∆ ,◊

 

Keywords

Cobalt / Niobium / Carbon / Melting diagram / Eutectic