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 M₂₃C₆ 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/cm², respectively),when compared with the same alloy in the investment as‐cast condition (−356 mV and 0.150 μA/cm²).

中文翻译：

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激光表面改性铸造 Co-Cr-Mo-C 合金的显微组织演变和腐蚀行为。

一种 Co-Cr-Mo-C 生物医用合金通过熔模铸造进行加工，并使用脉冲激光熔化对其表面进行改性。改性后的表面经历了快速凝固，并研究了其显微组织及其腐蚀性能。结果表明，与铸态相同合金相比，激光表面改性 (LSM) Co-Cr-Mo-C 合金具有更高的耐腐蚀性。微观结构测定表明 LSM Co-Cr-Mo-C 合金表现出缺乏显着的溶质偏析和主要的细胞形态，这是由于细胞固液前沿的发展。细胞形态的特征在于纳米级 M ₂₃ C ₆的精细分布细胞间区域的碳化物。此外，在细胞凝固区完全抑制了奥氏体 (γ) 到无热 ε-马氏体的转变。相比之下，铸态合金在枝晶间区域形成粗大的枝晶显微组织和粗大的碳化物。还存在溶质偏析以及无热 ε-马氏体 (13 pct)。结果表明，与投资相同的合金相比，LSM 合金在林格溶液中的耐腐蚀性能表现出更高的腐蚀电位和更低的腐蚀电流密度（分别为 -281 mV 和 0.032 μA/cm ²）。铸造条件（-356 mV 和 0.150 μA/cm ²）。