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研究了添加Sn和热处理对过共晶Al-Si-Cu-Mg合金(A390)显微组织与耐磨性的影响并对其机理进行了探讨。结果表明,铸态合金中的β-Sn相主要以颗粒和条状的形式存在于网状的Al2Cu相内,分布于Si相及α-Al相的晶界。在固溶时效处理过程中Sn促进共晶和初生Si相的球化;β-Sn相合并、聚集,一些形成Sn包Si的结构。铸态和热处理态的含Sn合金的磨损率和摩擦系数都小于无Sn合金的;和铸态相比,热处理后合金展现出低的磨损率和优良的耐磨性能。在低载荷下,Sn的添加使铸态A390合金从磨粒磨损和粘着磨损转变为单一的微弱磨粒磨损。在高载荷下,无Sn铸态合金的磨损方式包括磨粒磨损、粘着磨损和疲劳磨损,加入Sn后有效地抑制和避免了网状裂纹和疲劳磨损的产生。
The effects of Sn addition and heat treatment on the microstructure and wear resistance of hypereutectic Al-Si-Cu-Mg alloy (A390) were studied and the mechanism was discussed. The results show that the β-Sn phase in the as-cast alloy mainly exists in the reticular Al2Cu phase in the form of particles and stripes, which are distributed in the grain boundaries of Si phase and α-Al phase. In solution-aging treatment, Sn promotes eutectic and spheroidization of primary Si phase; β-Sn phase merges and aggregates, and some forms Sn-Si structure. The as-cast and heat-treated Sn-containing alloys exhibited lower wear rates and friction coefficients than those of the Sn-free alloys. The alloys showed low wear rate and excellent wear resistance compared with the as-cast ones. At low loads, the addition of Sn transformed the as-cast A390 alloy from abrasive and adhesive wear to a single, weak abrasive wear. Under high load, the wear modes of the Sn-free cast alloy include abrasive wear, adhesive wear and fatigue wear, and the addition of Sn can effectively restrain and avoid the occurrence of mesh cracks and fatigue wear.