Ni–Cr合金钎焊镀W金刚石的微观结构分析

Microstructure analysis of W–coated diamond brazing with Ni-Cr active filler

在1030℃、保温20 min的真空条件下,空烧镀W金刚石及用Ni–Cr合金粉末钎焊镀W金刚石。用X射线衍射仪分析镀W金刚石空烧前后镀层物相的变化,用扫描电镜和能谱仪综合分析金刚石界面微观结构、新生物相和形貌以及元素分布特征。结果表明:镀W金刚石的镀层物相由空烧前的W2C和单质W转变为空烧后的大量WC和少量W2C,且镀层未脱落。镀W金刚石钎焊后,其镀层和钎料中有少量的NiW相生成,在镀W金刚石/Ni–Cr合金界面处有柱状Cr7C3生成,在钢基体/Ni–Cr合金界面处有铬基金属间化合物生成。

Under vacuum condition of 1030℃for 20 min,W-coated diamond was heated and brazed with Ni-Cr alloy powder.X-ray diffraction(XRD)was used to analyze the phase changes of W-coated diamond before and after heating.Scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)were used to analyze the interface microstructure,the new phase,the morphology and that the element distribution.The results show that the coating phases of W-coated diamond change from W2C and W before heating to a large amount of WC and a small amount of W2C after heating,and that the coating does not fall off.After the W-coated diamond is brazed,there forms a small amount of NiW phase formed in the coating and the filler metal,the columnar Cr7C3 at the interface of W-coated diamond/Ni-Cr alloy,and the Cr-based intermetallic compound at the interface of steel substrate/Ni-Cr alloy.