镀钛金刚石钎焊界面微区结构分析

Brazing Interface Microstructure Analysis of Ti-Coated Diamond

采用Ag-Cu-Ti合金粉末在加热温度920℃保温时间8min条件下真空钎焊镀钛金刚石,运用X射线衍射仪、扫描电镜、能谱仪综合分析界面微观结构、元素分布特征及新生物相形貌。结果表明,镀钛金刚石镀层并不是单一钛的附着层,而是薄层TiC。钎焊过程中,镀钛金刚石磨粒与Ag-Cu-Ti钎料结合界面出现显微组织分层现象,原镀层与新生层厚度分别约为0.8μm和5μm。新生化合物在镀层表面呈短针状致密生长且有序连成片状,在镀层破损处有长约4μm,宽约1.5μm针状物,而在破损边缘处碳化物呈棒状背离镀层侧向生长。原子扩散动力学分析显示镀层晶体结构会限制游离C原子的无规则运动,使得新生TiC均匀分散形核并长大。

Ti-coated diamond is brazed in vacuum with heating temperature 920 ℃ for dwell time 8 min by using Ag-Cu-Ti alloy as filler.The interfacial microstructure,elements distribution and newlyformed phases are detected by X-ray diffraction,scanning electron microscope and energy dispersion spectrometer.The results show that during brazing,the delamination phenomenon in the interfacial layer takes place with the thickness of original coating and new layer about 0.8μm and 5μm,respectively.Newly-formed compound grows in form of short needle and into the shape of flake orderly on the coating surface.There is needle carbide about 4μm long and 1.5μm wide at the coating breakage,while the rod carbide grows from the plating at the edge.Atomic diffusion dynamic analysis shows that crystal structure limits the random motion of free C,making nucleation of newly-formed TiC evenly disperse and develop.