热处理对Al-Si-Cu合金力学性能、显微组织与磨损性能的影响

研究了不同热处理条件下Al-Si-Cu合金的力学性能、显微组织及磨损性能.结果表明:与铸态合金相比,T6态合金的晶粒最为细小,Si、Al2Cu和Al Fe Mn Si第二相尺寸变小、变圆整且分布均匀,其力学性能和耐磨性能最好.当载荷小于500 N时,T6态和铸淬态合金的耐磨性能相当,二者表现为磨粒磨损;载荷为500~1 000 N时,Si相受水平方向塑性流变应力作用均匀分布在磨面表面,改善了润滑效果使摩擦系数降低,虽然开始向黏着磨损机制转变,但合金仍保持了较好的耐磨性能;载荷大于1 000 N时,Si相和Al2Cu相周围出现了微裂纹和严重的撕裂状的塑性变形,摩擦系数增大,逐步向剥层磨损转变,合金耐磨性能显著下降.

Effect of Heat Treatment on Mechanical Properties, Microstructures and Wear Resistance of Al-Si-Cu Alloy

Mechanical properties, microstructure and wear performance of Al-Si-Cu alloy after heat treatment were investigated. The results show that T6 heat treatment rendered the alloy finer microstructure (matrix and uniformly distributed second phases, i.e. Si phase, Al₂Cu phase and AlFeMnSi phase) in comparison with the as-cast alloy. The mechanical properties and wear performance of T6 state alloy are better than that of the as-cast alloy. At load lower than 500 N, T6 state alloy and cast-quenching state alloy had comparable wear performance with dominant wear mechanism of abrasive wear. At load between 500 N and 1 000 N, horizontal plastic flow stress gave birth to uniformly distributed Si phase on the worn surface, which improved the tribological performance. In addition, transition of abrasive wear to abrasive wear and adhesive wear occurred. At load higher than 1 000 N, micro cracks and severe tearing plastic deformation around the Si phase and Al₂Cu phase were observed and this increased the friction coefficient. The wear mechanism transformed to delamination wear and the wear performance of the alloy became worse.