Behaviors of (Ti, C)-containing cast (CO, Ni)-based superalloys in oxidation and creep at 1200°С

Keywords

Co and Ni alloys, TiC carbides, chromium carbides, creep resistance, high temperature oxidation.

Cite as

Ozouaki S., and Berthod P. Behaviors of (Ti, C)-containing cast (CO, Ni)-based superalloys in oxidation and creep at 1200°С. Physicochemical Mechanics of Materials. 2022. 58(5), 048-054.

Abstract

Six alloys (25 wt% Cr, 0.4 C, 1.6 Ti, Co and Ni (bal.)) were prepared by casting for eva­luating their oxidation and creep properties at 1200°C. Their microstructures consist of a dendritic matrix with eutectic carbides in the interdendritic spaces. Carbides are TiC for the alloys richer in Co than in Ni, and chromium carbides in the alloys richer in Ni than in Co. Differential thermal analysis shows that all alloys start melting above 1250°C. The oxidation tests in air at 1200°C allow observing a chromia–forming behavior of the alloys rich in nickel better than the cobalt alloys. In contrast, the creep resistance tests at 1200°C demonstrate an undeniable superiority of the alloys rich in cobalt. Good compromise for both types of high temperature behavior appears to be obtained by a Co-base alloy con­tain­ing nickel as minor element but with significant proportion in nickel (15–30 wt% Ni).

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