Effect of cobalt on aging of martensite and ferrite in Fe-Co-W and Fe-Co-Mo alloys

Abstract

1. The addition of cobalt to maraging Fe-Co-W and Fe-Co-Mo alloys broadens the γ region at high temperatures, which permits the γ→α transformation by the martensite mechanism during subsequent conling. 2. The high density of dislocations and other defects that result from the displacement mechanism of the γ»α transformation leads not only to hardening of the matrix but also creates conditions favorable for the formation of large numbers of centers for precipitation of phases during aging. 3. Cobalt substantially accelerates the aging process. The initial stage of aging is slowed down in alloy V10, but there is no incubation period in alloys V10K10 and V10K15, which may indicate a small effect of activation barriers determining the formation of precipitates on dislocation.