The microstructure evolution and mechanical properties of WC-cu-10Ni-5Mn-3Sn cemented carbides containing NbC prepared by pressureless melt infiltration

• Published in: International journal of refractory metals & hard materials Vol. 126; p. 106929
• Main Authors: You, Fei, Li, Xiulan, Zhou, Xinjun, Chen, Yao, Li, Wei, Zhang, Yuan, Xiong, Can, Guo, Zhengyu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2025
• Subjects: Mechanical properties; Microstructure; NbC; Pressureless melt infiltration; WC-based cemented carbides; Mechanical properties; WC-based cemented carbides; Microstructure; NbC; Pressureless melt infiltration
• ISSN: 0263-4368
• DOI: 10.1016/j.ijrmhm.2024.106929

WC-based cemented carbides with different contents of NbC (0, 0.6, 0.8, 1.0, 1.2, and 1.4 wt%) are prepared via pressureless melt infiltration at 1200 °C for 1.5 h. Microstructure evolution regularity of WC-based cemented carbide is investigated to establish the effect of NbC addition and microstructure peculiarities on mechanical properties (flexural strength, hardness, and impact toughness) of final product. Experimental results reveal that NbC firstly dissolves in binder alloy during melt infiltration, which slows down dissolution-precipitation reaction of WC, thus refining WC grains. With the increase in NbC content, average WC grain size shows varying trend, achieving the minimum (3.779 μm) at NbC addition of 1 wt%. When NbC is added in smaller amounts, Nb is mainly distributed throughout binder alloy. With the increase in NbC content, Nb elements tend to form aggregates and attach to WC particle boundaries. Some WC and NbC also decompose under experimental conditions. At NbC addition greater than 1 wt%, decomposition products (Nb, W, and C) combine with other elements in binder phase to form new phases such as (Nb,W)C, Ni2W4C, Nb2C, and Nb4Ni2C. These phases further act as bridges for WC grain coarsening. Meanwhile, excessive NbC is detrimental to mechanical properties of the alloy. With the increase in NbC content, hardness and flexural strength of the alloy increase and then decrease, reaching the maximum values of 93.4 HRA and 1808.786 MPa, respectively, at 1 wt% NbC addition. In turn, impact toughness of the alloy shows consistently downward trend. Therefore, changes in mechanical properties of WC-based cemented carbides are mainly related to WC grain size, the appearance of new phases in binder phase, and their morphology. •The effect of NbC dopant on the microstructural evolution and mechanical properties of WC-Cu-10Ni-5Mn-3Sn alloy is investigated via pressureless melt infiltration.•A new phase appears in the alloy: W, Ni2W4C, (Nb,W)C, Nb4Ni2C, Nb2C.•The hardness and flexural strength vary with the increase of NbC dopant content, reaching their maxima (93.4 HRA and 1808.786 MPa, respectively) at 1.0 wt% NbC content. At the same time, the most optimal impact toughness (4.65 J.cm−2) is achieved in the undoped alloy.