Deformation mechanism of harmonic structure designed Co–Cr–Mo alloy

Co–Cr–Mo alloy (CCM) is widely used as structural material for biomedical applications, such as coronary stent, hip and knee replacements and dental implants, due to their excellent biocompatibility, wear resistance, corrosion and mechanical properties. In the present work, ‘harmonic structure’ design is proposed for CCM with improved mechanical properties. The harmonic structure consists of coarse-grained (CG) regions called ‘core’ surrounded by a continuously connected 3D network of ultra-fine grain (UFG) regions called ‘shell’. Harmonic structure CCM compacts were fabricated by a combination of severe plastic deformation and powder metallurgy process. Mechanical milling was used to produce UFG region on the surface of powder by controlling the milling conditions, leading to bimodal structure in the milled powder. Subsequently, the mechanically milled bimodal powder was sintered by Spark Plasma Sintering. Sintered compacts of milled powder exhibited ‘harmonic structure’ and they demonstrated out...