Abstract The influence of Cr and W addition on microstructure and mechanical properties of Mo2FeB2-based cermets, prepared by multi-step sintering, is systematically evaluated by XRD, SEM, EDS, and TEM. After liquid-phase sintering, the final microstructure of Cr-doped Mo2FeB2-based cermets is similar to that of traditional Mo2FeB2-based cermets. The cermet, with 2.5% Cr content, exhibits superior comprehensive mechanical properties, i.e., Rockwell hardness, transverse rupture strength (TRS) and fracture toughness of 87.6 HRA, 2179 MPa and 21.7 MPa m1/2, respectively. In contrast, for W-doped Mo2FeB2-based cermets, a large amount of W-enriched (Mo,Fe,W)3B2 solid solutions precipitated around undissolved Mo2FeB2 particles, resulting in the formation of black core/gray rim structure. Particularly, a transition layer, with several atomic layer thickness, is observed between (Mo,Fe,W)3B2 rim phase and Fe-based binder phase, which corresponds to B-deficient (Mo,Fe,W)3B2−x orthorhombic boride phase. Moreover, the lattice mismatch between (Mo,Fe,W)3B2 and (Mo,Fe,W)3B2−x is found to be 1.9%. When doped with 5 wt% W, Mo2FeB2-based cermet exhibit superior comprehensive mechanical properties with Rockwell hardness of 84.6 HRA, TRS of 2088 MPa and fracture toughness of 24.4 MPa m1/2. The increase of fracture toughness (KIC) can be ascribed to the presence of W-rich transition layer.

中文翻译：

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添加Cr和W对多步烧结Mo2FeB2基金属陶瓷显微组织和力学性能的影响

摘要 采用XRD、SEM、EDS和TEM系统评价了Cr和W添加量对多步烧结法制备的Mo2FeB2基金属陶瓷的显微组织和力学性能的影响。液相烧结后，掺铬的 Mo2FeB2 基金属陶瓷的最终微观结构与传统的 Mo2FeB2 基金属陶瓷相似。含 2.5% Cr 的金属陶瓷表现出优异的综合力学性能，即洛氏硬度、横向断裂强度 (TRS) 和断裂韧性分别为 87.6 HRA、2179 MPa 和 21.7 MPa m1/2。相比之下，对于掺 W 的 Mo2FeB2 基金属陶瓷，大量富含 W 的 (Mo,Fe,W)3B2 固溶体在未溶解的 Mo2FeB2 颗粒周围沉淀，导致形成黑色核/灰边结构。特别是过渡层，在 (Mo,Fe,W)3B2 边缘相和 Fe 基粘结相之间观察到几个原子层厚度，这对应于 B 缺陷的 (Mo,Fe,W)3B2-x 正交硼化物相。此外，发现 (Mo,Fe,W)3B2 和 (Mo,Fe,W)3B2-x 之间的晶格失配为 1.9%。当掺入 5 wt% W 时，Mo2FeB2 基金属陶瓷表现出优异的综合力学性能，洛氏硬度为 84.6 HRA，TRS 为 2088 MPa，断裂韧性为 24.4 MPa m1/2。断裂韧性（KIC）的增加可归因于富W过渡层的存在。Mo2FeB2 基金属陶瓷表现出优异的综合力学性能，洛氏硬度为 84.6 HRA，TRS 为 2088 MPa，断裂韧性为 24.4 MPa m1/2。断裂韧性（KIC）的增加可归因于富W过渡层的存在。Mo2FeB2 基金属陶瓷表现出优异的综合力学性能，洛氏硬度为 84.6 HRA，TRS 为 2088 MPa，断裂韧性为 24.4 MPa m1/2。断裂韧性（KIC）的增加可归因于富W过渡层的存在。