激光熔覆SiCf/Ti-6Al-4V复合材料界面特性与微观力学性能研究

Interface characteristics of laser cladding SiCf/Ti-6Al-4V compositesand micromechanical properties

摘要:

针对激光熔覆制备SiCf/Ti-6Al-4V复合材料过程中反应时间短和扩散时间短的问题，开展了不同真空热暴露条件下SiCf/Ti-6Al-4V复合材料界面特性和微观力学性能的研究。借助扫描电子显微镜SEM、能谱仪EDS、透射电子显微镜TEM、纳米压痕仪，表征了经不同温度、不同时间真空热暴露后界面反应层厚度、界面处化学成分、微观力学性能。研究发现，激光熔覆叠层技术制备复合材料过程中增强体、C涂层、基体之间会发生界面反应，其主要界面反应产物为TiC。短时真空热暴露会使得界面反应层厚度增加，C涂层厚度减小，随着热暴露时间延长，反应层的生长符合抛物线规律，反应的动力学参数频率因子k0 =6.005×10-3 m.s-1/2，反应激活能Q=143.13 kJ.mol-1。经900 ℃短时真空热暴露，纤维、C涂层、基体及界面反应层的硬度值和弹性模量没有发生明显的变化，表明该材料在900℃及以下温度具有良好的短时热稳定性。

Abstract:

Abstract:SiCf/Ti-6Al-4V composites prepared by laser cladding have short reaction time and diffusion time. The interfacial properties and micromechanical properties of SiCf/Ti-6Al-4V composites under different vacuum thermal exposure conditions were studied. By means of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM) and nanoindentation instrument, the thickness of the reaction layer, chemical composition at the interface and micromechanical properties at different temperatures and times after vacuum thermal exposure were characterized. It is found that the interfacial reaction between reinforcer, C coating and matrix occurs in the process of laser cladding laminated composites, and the main interfacial reaction product is TiC. Short time vacuum thermal exposure increases the thickness of the interfacial reaction layer and decreases the thickness of the C coating. With the extension of thermal exposure time, the growth of the reaction layer conforms to a parabolic law. The kinetic parameters of the reaction are frequency factor k0 =6.005×10-3 m.s-1/2, and activation energy Q=143.13 kJ.mol-1. The hardness and elastic modulus of fiber, C coating, substrate and interfacial reaction layer do not change obviously after 900℃ short-time vacuum thermal exposure, indicating that the material has good short-time thermal stability at 900℃ and below.