原位反应合成金属间化合物激光合金化层的组织及抗磨性能

以近等原子比的NiTi合金粉末为原料,利用连续波高功率Nd-YAG激光器在6061Al合金表面制备了Ni-Al和Ti-Al金属间化合物改性层,采用扫描电子显微镜、X射线能谱仪、X射线衍射仪、显微硬度计及摩擦磨损试验机分析了合金化层的组织形貌、结构、成分、硬度分布及磨损性能.研究结果表明,该激光表面改性层主要由Ni3Al和TiAl3金属间化合物组成;采用合适的保护措施和激光处理工艺参数,可控制改性层产生孔洞和裂纹倾向,从而获得与基体具有良好冶金结合的致密金属间化合物合金激光改性层;与此同时,Ni-Al和Ti-Al金属间化合物改性层可有效地改善铝合金的抗磨性能.

Microstructure and Wear-Resistance of In-Situ Synthetic Intermetallic Compound Modification Coating Formed on Al Alloy Substrate by Laser Alloying

The surface modification coating composed of Ti-Al and Ni-Al intermetallic compounds was fabricated on 6061Al substrate using a high-power continuous wave Nd-YAG laser, by means of laser surface alloying of NiTi powders as the raw material. The microstructure, surface morphology, composition distribution, hardness profile, and wear-resistance of the surface alloying coating were analyzed using X-ray diffraction, scanning electron microscopy, microhardness measurement, and friction and wear test. It was found that the NiTi powders were successfully alloyed onto the aluminium alloy surface by way of overlapping single track at the optimal process parameters, and the resulting surface alloying coating had good metallurgical bonding with the Al alloy substrate. The surface alloy coating was compact and free of crack, and it was mainly composed of TiAl_3 and Ni_3Al intermetallic compounds dendrites. The hardness of the laser-alloyed surface was 3 to 5 times as much as that of the Al6061 alloy substrate, while its wear-resistance was dramatically increased than the 6061Al substrate.