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采用扫描电镜、能谱分析、金相显微镜与WDW-100KN万能拉伸试验机研究Al-7Sn-1.1Ni-Cu-0.2Ti轴承合金的微观组织与力学性能,结合盘-销式摩擦磨损试验机考察合金不同组织状态的润滑性能.结果表明:Al-7Sn-1.1Ni-Cu-0.2Ti合金凝固收缩率为1.13%,铸态抗拉强度、屈服强度、伸长率与布氏硬度分别为191,147MPa,15.6%与34.6HBS,随着低温时效与退火热处理过程的进行,抗拉强度略有上升,屈服强度保持不变,伸长率与布氏硬度均呈现出先上升后下降的变化趋势;沿晶界分布的共晶Sn相形貌受界面张力作用逐步由板片状与骨骼状转变为层片状与短棒状,部分吸热脱溶析出在晶界处形成空腔结构,初生α-Al基体平均晶粒尺寸为182μm.与铸态和340℃退火6h相比,经175℃时效10h后,摩擦因数降低了28.6%与78.6%,体积磨损量减少了157.1%与471.4%,断口形貌以沿晶断裂与韧窝断裂为主.

The microstructures and mechanical properties of Al-7Sn-1.1Ni-Cu-0.2Ti alloy were studied by using SEM, EDS, OM and WDW-100KN universal tensile testing machine, the lubricating properties were completed by the disk-pin testing machine.The results show that the solidification shrinkage of alloy is 1.13%;the tensile strength, yield strength, elongation and Brinell hardness in the as-cast state are 191, 147MPa, 15.6% and 34.6HBS, with the executing of low temperature aging and annealing process, the tensile strength increases slightly and the yield strength has no significant changes;the elongation and Brinell hardness exhibit the tendency of increasing firstly and then decreasing.Morphology of eutectic Sn phase that distributes nearby the grain boundary transforms from plate-like shape and bone-shape to lamellar and short rod gradually under the function of the interfacial tension.Due to some eutectic phase melts by absorbing energy from heat treatment process, cavity structure forms around grain boundaries, the average grain size of primary α-Al substrate is 182μm.Comparing with the as-cast and annealing at 340℃ for 6h states, the friction coefficient decreases by 28.6% and 78.6%, together with the wear volume reduces by 157.1% and 471.4% after aging at 175℃ for 10h, the fracture morphology shows mainly intergranular fracture and dimple fracture.