Microstructure and mechanical properties of biomedical Co–29Cr–8Mo alloy wire fabricated by a modified melt-spinning process

A modified in-rotating-water spinning process has been applied for producing the alloy wire of Ni-free Co–29Cr–8Mo suitable for biomedical use. The microstructure and tensile properties of the as-spun and heat-treated wires were investigated using backscattered electron microscopy, X-ray diffraction analyses and tensile tests. The microstructure of the as-spun wire exhibits a cellular structure and evolves into an equiaxed and fine-grained structure with an average grain size of several micrometers, containing σ-phase precipitates after heat treatment at 1373 K. Grains increase in size and reach an average diameter ranging from 10 to 20 μm at 1473 K. The crystal structure of the as-spun wire changes from face-centered cubic to strain-induced hexagonal close-packed martensite through wiredrawing. The wiredrawing, combined with heat treatments, improves the mechanical properties of the as-spun wire. The present modified melt-spinning process is an effective method to produce Ni-free Co–Cr–Mo alloy wire for biomedical applications.