Functionally graded WC–Co cemented carbides (FG WC–Co) with plate-like WC grains were fabricated by carburizing of cemented carbides with no η phase. The phase composition and microstructure of FG WC–Co were investigated by XRD, SEM and EDX. The results showed that a cobalt-deficient layer was formed due to difference in affinity among carbon and other alloying elements. WC grain size increased while the ratio of side length to thickness decreased slightly in the surface zone due to difference of growth rate between different planes of WC grains. Moreover, FG WC–Co possessed an 80 μm deep cobalt-deficient layer, and showed excellent mechanical properties with a surface hardness of 1748 HV and fracture toughness of 9.6 MPa · m1/2 in the surface zone.

中文翻译：

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具有板状WC颗粒的功能级配WC-Co硬质合金的制备

具有板状 WC 晶粒的功能梯度 WC-Co 硬质合金 (FG WC-Co) 是通过对没有 η 相的硬质合金进行渗碳来制造的。通过XRD、SEM和EDX研究了FG WC-Co的相组成和微观结构。结果表明，由于碳与其他合金元素的亲和力不同，形成了缺钴层。由于WC晶粒不同平面之间的生长速度不同，WC晶粒尺寸增加，而表面区的边长与厚度比略有下降。此外，FG WC-Co 具有 80 μm 深的缺钴层，表现出优异的机械性能，表面硬度为 1748 HV，表面区断裂韧性为 9.6 MPa·m1/2。