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In this research, the microstructure and corrosion properties of rapidly solidified Co-Cr-Mo-C alloy as an advanced biomaterial alloy were studied. The use of rapid solidification casting method represents significant changes in not only the amount of formed e-HCP phase, which is strongly influenced by rapid solidification, but also in electrochemical behavior and solidified structure. In this research, rapid solidified Co-Cr-Mo-C alloy is studied using OM, SEM, EDS, XRD, and dynamic potentiostate.  Co-alloy ingots were melted into an induction furnace filled by argon gas and casted into a V-shape sand and chill copper molds to prepare rapid solidified samples and its properties were measured in different cooling rates. The microstructure examination demonstrating the structure of alloy is mainly consist of columnar dendritic structure with the distribution of carbides within primary and secondary dendrites arms and finer dendritic structure along with modified carbide distribution will be achieved by rapid solidification. This structure will improve alloy’s corrosion behavior and reduces its corrosion rate when it is tested in Ringer’s solution as an electrolyte.

A Co-Cr-Mo-C biomedical alloy was processed by investment casting, and its surface was modified using pulsed laser melting. The modified surface underwent rapid solidification, and the exhibited microstructure as well as its corrosion properties were investigated. It was found that the laser surface modified (LSM) Co-Cr-Mo-C alloy possesses enhanced corrosion resistance when compared with the same alloy in the as-cast condition. Microstructural determinations indicated that the LSM Co-Cr-Mo-C alloy exhibited a lack significant solute segregation and a predominantly cellular morphology as a result of the development of a cellular solid-liquid front. The cellular morphology was characterized by a fine distribution of nano-scale M 23 C 6 carbides at the intercellular regions. Moreover, the austenite (γ) to athermal ε-martensite transformation was totally suppressed in the cellular solidified regions. In contrast, the as-cast alloy develops a coarse dendritic microstructure with coarse carbides in the interdendritic regions. Solute segregation is also present, as well as athermal ε-martensite (13 pct). It was found that the corrosion resistance of the LSM alloy in the Ringer solution exhibits improved corrosion potential and a reduced corrosion current density (−281 mV and 0.032 μA/cm 2 , respectively),when compared with the same alloy in the investment as-cast condition (−356 mV and 0.150 μA/cm 2).