Abstract MoSiB-based alloys are extremely promising ultrahigh–temperature materials, owing to their high melting points, good thermal stability, and excellent elevated-temperature mechanical properties. However, their fabrication is limited to conventional manufacturing techniques. In this work, a MoSiBTiC multiphase alloy, mainly consisting of Mo solid solution (Moss), Mo5SiB2 (T2), and TiC phases, was fabricated by laser powder bed fusion (L-PBF) using ball-milled alloy powders; subsequently, the effect of hot isostatic pressing (HIP) on its microstructure and fracture toughness was investigated. Due to the non-equilibrium metallurgical characteristics of L-PBF, the as-built alloy included uniform and fine-grained structures, as well as internal microcracks. The length of microcracks was effectively reduced with the assistance of the TiC bridging effect during HIP. As revealed by a high-resolution transmission electron microscope, the TiC was uniformly dispersed and was in close contact with the Moss or T2 phase. Consequently, the MoSiBTiC multiphase alloy exhibited a high fracture toughness of 9.0 MPa(m)1/2 after HIP at 1973 K. This work could be an important step towards the fabrication of high-performance refractory components with advanced properties in ultrahigh–temperature use.

中文翻译：

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热等静压对激光增材制造MoSiBTiC多相合金组织和断裂韧性的影响

摘要 MoSiB基合金具有熔点高、热稳定性好、高温力学性能优良等优点，是极具发展前景的超高温材料。然而，它们的制造仅限于传统的制造技术。在这项工作中，使用球磨合金粉末通过激光粉末床熔融 (L-PBF) 制备了主要由 Mo 固溶体 (Moss)、Mo5SiB2 (T2) 和 TiC 相组成的 MoSiBTiC 多相合金；随后，研究了热等静压 (HIP) 对其微观结构和断裂韧性的影响。由于 L-PBF 的非平衡冶金特性，建成后的合金包括均匀的细晶结构，以及内部微裂纹。在 HIP 过程中，TiC 桥接效应有效地减少了微裂纹的长度。高分辨率透射电子显微镜显示，TiC 均匀分散并与 Moss 或 T2 相紧密接触。因此，MoSiBTiC 多相合金在 1973 K 进行 HIP 后表现出 9.0 MPa(m)1/2 的高断裂韧性。这项工作可能是制造具有超高温使用性能的高性能耐火部件的重要一步.