Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications
AbstractBinary Co-Cr alloys containing various Cr contents were vacuum induction melted and cast into wedge-shaped copper molds. It was intended to develop a microstructure (1) free from interdendritic segregation and porosity; (2) having minimal intermetallic precipitates; and (3) suitable for biomedical applications. The resultant microstructures were evaluated from sections obtained longitudinally and centrally in the plane normal to the diverging wedge faces. All ingots showed a dendritic microstructure with some characteristic features. For instance, in Co-20–30 wt. % Cr alloys, the chilled cast microstructures consisted of columnar dendrites without interdendritic segregation, a minimum of intermetallic precipitates, and the presence of a predominantly athermal HCP ε-martensite (>80 vol. %). In addition, the metastable FCC γ-Co phase was identified by X-ray diffraction and scanning electron microscopy. In the case of 35–44 wt. % Cr cobalt alloys, a eutectic constituent including the σ-phase were found to develop in the interdendritic regions. From this work, a Co-20 wt. % Cr alloy was chosen for further investigation after heat treating below the γ/ε transition temperature. The resultant tensile strength and ductility were further improved after applying a heat treatment at 730 °C for 30 min, obtaining values of elongation of 26% as compared with 2.55 < 5 of elongation in the as cast condition. Also, the alloy corrosion resistance in artificial saliva was investigated. It was found that the exhibited corrosion rates for the as-cast and heat-treated conditions are between those reported for other similar systems. View Full-Text
Share & Cite This Article
Ramirez-Ledesma, A.L.; Lopez, H.F.; Juarez-Islas, J.A. Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications. Metals 2016, 6, 188.
Ramirez-Ledesma AL, Lopez HF, Juarez-Islas JA. Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications. Metals. 2016; 6(8):188.Chicago/Turabian Style
Ramirez-Ledesma, Ana L.; Lopez, Hugo F.; Juarez-Islas, Julio A. 2016. "Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications." Metals 6, no. 8: 188.
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.