Mechanical Properties of Co Alloys Based on a E2₁ Type Co₃AlC Intermetallic Compound

Abstract

Alloy design of a new Co-base heat resisting alloy is being pursued. Similar to Ni₃Al in the Ni-base superalloys, the introduction of E2₁ type intermetallic compound Co₃AlC as a strengthening phase in a Co solid solution matrix is being attempted. Three experimental alloys are prepared which consist of either two or three phases. Two phase alloys consist of the Co terminal solid solution and the Co₃AlC, while a three phase alloy contains additional B2 phase based on CoAl. Temperature dependence of strength is measured for all the three alloys to reveal that the alloys could exhibit comparable intermediate to high temperature strength with Ni-base superalloys and that, most astonishingly, are found to be quite ductile over all the test temperature including 77 K.