Caracterización microestructural de una aleacion Co-20% Cr solidificada en molde metalico

Abstract

It was performed a microstructural characterization of a Co-20 wt.% Cr alloy solidified in a copper metal mold with a cooling rate of 450 K/s, which was selected from a group of Co-20 to 44 wt.% Cr alloys, systematically solidified at different cooling rates (130, 230 and 450 K/s), previously reported [1], with the purpose of reporting the resulting microstructure, which consisted of columnar dendrites without the presence of eutectic phase or intermetallic compounds in interdendritic regions. A cooling rate of 450 K/s was enough to obtain columnar dendrites which were composed of more than 90% of martensite HCP ε-Co, the remainder being the metastable phase FCC γ-Co. It was identified that a cooling rate between 130 and 450 K/s generates defects such as vacancies, dislocations and stacking faults. The latter served as nucleation sites for the growth of martensite HCP γ-Co plates.