Abstract The strength and plasticity of metallic materials usually exhibit a trade-off relation. This study reports a simultaneous improvement in the ultimate tensile strength (UTS) and uniform elongation (UE) of Ti-24Nb-4Zr-8Sn (Ti2448) fabricated by selective laser melting (SLM), relative to those produced via forging. Detailed microstructural characterization reveals that the outstanding tensile property may result from the bi-model structure that forms during the rapid cooling associated with SLM. Coarse grains are surrounded by fine grains within the melt pool, which causes a back stress during tension. The back stress provides additional strain-hardening capacity, which postpones the initiation of necking and then leads to the simultaneous improvement of the strength and plasticity (SISP) of the Ti2448 alloy. Furthermore, the tensile property of the SLM-fabricated sample is anisotropic which is strongly related to the irregular shape of the melt pool.

中文翻译：

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激光选区熔化制备Ti-24Nb-4Zr-8Sn同时提高强度和塑性

摘要 金属材料的强度和塑性通常呈现一种权衡关系。本研究报告了通过选择性激光熔化 (SLM) 制造的 Ti-24Nb-4Zr-8Sn (Ti2448) 的极限抗拉强度 (UTS) 和均匀伸长率 (UE) 的同时提高，相对于通过锻造生产的那些。详细的微观结构表征表明，出色的拉伸性能可能源于与 SLM 相关的快速冷却过程中形成的双模型结构。粗晶粒被熔池内的细晶粒包围，这会在拉伸过程中产生背应力。背应力提供了额外的应变硬化能力，推迟了颈缩的开始，然后导致 Ti2448 合金的强度和塑性 (SISP) 同时提高。此外，