Additive Manufacturing of Cobalt-Based Dental Alloys: Analysis of Microstructure and Physicomechanical Properties
Additive Manufacturing of Cobalt-Based Dental Alloys: Analysis of Microstructure and Physicomechanical Properties
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DOI：
10.1155/2018/8213023
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发表时间：
2018-01-01
影响因子：
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通讯作者：
Oechsner, Andreas
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文献类型：
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作者：
Hitzler, Leonhard;Alifui-Segbaya, Frank;Oechsner, Andreas
据称，随着选择性激光熔化 (SLM) 技术对金属增材制造的显着改进，钴基合金熔模铸造的局限性已不再是问题。尽管有这些优点，金属器件可能会表现出与构建方向相关的机械各向异性，这可能因此影响它们的“体内”性能。此外，关于使用设备之前必须完成的必要成分和后处理步骤（例如，用于缓解应力的热处理），还没有确凿的证据。在本文中，我们评估了分别采用直接金属打印和 LaserCUSING SLM 系统构建的三元钴铬钼 (Co-Cr-Mo) 和钴铬钨 (Co-Cr-W) 合金在竣工 (AB) 和热处理 (HT) 条件下在 0 度、30 度、60 度和 90 度倾斜 (Phi) 条件下的微观结构。该研究还检查了拉伸性能（杨氏模量，E；屈服强度，R-P0.2；断裂伸长率，At；极限拉伸强度，R-m）、相对密度（RD）、显微硬度（HV5）和宏观硬度（HV20）作为合金的相关物理机械性能。获得的数据表明，Co-Cr-Mo 合金经过短暂且经济有效的热处理周期后，拉伸性能和 HV 值得到改善；然而，该过程并未使合金的微观结构均匀化。与 AB 形式相比，Co-Cr-W 的退火热处理导致显着的各向同性特征，E 和 A(t) 增加（Phi = 90 度除外），而 R-P0.2、R-m 和 HV 值则降低。类似地，AB Co-Cr-W 中的交错焊道结构在热处理过程中被去除，导致显微组织完全再结晶。两种合金均表现出无缺陷的微观结构，RD 超过 99.5%。
The limitations of investment casting of cobalt-based alloys are claimed to be less problematic with significant improvements in metal additive manufacturing by selective laser melting (SLM). Despite these advantages, the metallic devices are likely to display mechanical anisotropy in relation to build orientations, which could consequently affect their performance "in vivo." In addition, there is inconclusive evidence concerning the requisite composition and postprocessing steps (e.g., heat treatment to relieve stress) that must be completed prior to using the devices. In the current paper, we evaluate the microstructure of ternary cobalt-chromium-molybdenum (Co-Cr-Mo) and cobalt-chromium-tungsten (Co-Cr-W) alloys built with direct metal printing and LaserCUSING SLM systems, respectively, at 0 degrees, 30 degrees, 60 degrees, and 90 degrees inclinations (Phi) in as-built (AB) and heat-treated (HT) conditions. The study also examines the tensile properties (Young's modulus, E; yield strength, R-P0.2; elongation at failure, At; and ultimate tensile strength, R-m), relative density (RD), and microhardness (HV5) and macrohardness (HV20) as relevant physicomechanical properties of the alloys. Data obtained indicate improved tensile properties and HV values after a short and cost-effective heat-treatment cycle of Co-Cr-Mo alloys; however, the process did not homogenize the microstructure of the alloy. Annealing heat treatment of Co-Cr-W led to significant isotropic characteristics with increased E and A(t) (except for Phi = 90 degrees) in contrast to decreased R-P0.2, R-m, and HV values, compared to the AB form. Similarly, the interlaced weld-bead structures in AB Co-Cr-W were removed during heat treatment, which led to a complete recrystallization of the microstructure. Both alloys exhibited defect-free microstructures with RD exceeding 99.5%.