Abstract Metal additive manufacturing (AM) has developed rapidly over the last decade to become a disruptive technology capable of revolutionizing the way that products from various industrial sectors such as biomedical, aerospace, automotive, marine and offshore are designed. Early adopters of the technology like the biomedical and aerospace industries have shown that the better-designed components offer substantial performance improvements over current designs. However, in-depth and comprehensive views on the microstructure and mechanical properties of additively manufactured metals and alloys are less reported. To realize the full design potential that metal AM can offer, especially for load-bearing structural components, it is imperative to provide a thorough understanding on the anisotropic and heterogeneous microstructure and mechanical properties that often occur within metal AM parts. This paper outlines a broad range of metal AM technologies and reviews literatures on the anisotropy and heterogeneity of microstructure and mechanical properties for metal AM parts. It can be highlighted that the contributing factors to the anisotropy and heterogeneity within metal AM parts were either their unique microstructural features or manufacturing deficiencies. Concluding remarks on the state-of-the-art research regarding this topic and the possible solutions to overcome the anisotropy and heterogeneity of metal AM parts are provided.

中文翻译：

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金属增材制造中微观结构和机械性能的各向异性和异质性：批判性评论

摘要 金属增材制造 (AM) 在过去十年中发展迅速，成为一种颠覆性技术，能够彻底改变生物医学、航空航天、汽车、船舶和近海等各个工业部门的产品设计方式。生物医学和航空航天工业等技术的早期采用者已经表明，设计更好的组件比当前设计提供了显着的性能改进。然而，关于增材制造金属和合金的微观结构和机械性能的深入和全面的观点鲜有报道。为了实现金属增材制造可以提供的全部设计潜力，特别是对于承重结构部件，必须全面了解金属增材制造部件中经常出现的各向异性和异质微观结构和机械性能。本文概述了广泛的金属增材制造技术，并回顾了有关金属增材制造部件微观结构和机械性能的各向异性和异质性的文献。可以强调的是，导致金属增材制造部件内各向异性和异质性的因素要么是它们独特的微观结构特征，要么是制造缺陷。提供了有关该主题的最新研究的结论，以及克服金属增材制造部件各向异性和异质性的可能解决方案。本文概述了广泛的金属增材制造技术，并回顾了有关金属增材制造部件微观结构和机械性能的各向异性和异质性的文献。可以强调的是，导致金属 AM 零件内各向异性和异质性的因素要么是它们独特的微观结构特征，要么是制造缺陷。提供了有关该主题的最新研究的结论，以及克服金属增材制造部件各向异性和异质性的可能解决方案。本文概述了广泛的金属增材制造技术，并回顾了有关金属增材制造部件微观结构和机械性能的各向异性和异质性的文献。可以强调的是，导致金属增材制造部件内各向异性和异质性的因素要么是它们独特的微观结构特征，要么是制造缺陷。提供了有关该主题的最新研究的总结性评论以及克服金属增材制造部件的各向异性和异质性的可能解决方案。