(盐城工学院 材料工程学院，盐城 224051)
摘 要: 对过共晶Al-20%Si合金进行变质和合金化处理，并在不同环境温度下进行摩擦磨损测试。结果表明，经过Cu-P中间合金变质后的初晶Si相和共晶Si相明显细化和钝化，再添加1.5%Zr (质量分数)后初晶Si相的粒径更小，为20~40 μm，且趋于球形。共晶Si相呈纤维状或短棒状，长度明显变短(≤50 μm)。以上3种合金随环境温度的升高都出现了从轻微磨损到严重磨损的转变，且转变载荷随环境温度的升高而减小。室温下3种合金的磨损曲线差异不大，但在较高的环境温度下，经变质和合金化处理后，发生磨损转变的载荷明显减小，细化的初晶和共晶Si相提高了合金的性能，特别是高温耐磨性能。这归因于细化的Si相避免了应力集中和磨损过程中的直接破碎化，在高温磨损阶段磨损表面易形成机械混合层，阻碍合金与对磨副的直接接触，降低磨损率。
关键字: 过共晶Al-Si合金；变质处理；合金化；摩擦；磨损
（School of Materials Engineering, Yancheng Institute of Technology, Yancheng 224051, China）
Abstract:The hypereutectic Al-20%Si alloy was treated by modification and alloying. The wear tests were conducted under various ambient temperatures. The results show that after modification of Cu-P master alloy, the primary and eutectic Si phases are significantly refined and passivated. After adding 1.5%Zr (mass fraction) again, the shape of primary Si becomes spherical and the particle size becomes smaller, being 20-40 μm; a fibrous or short rod shape eutectic Si phase forms in the modified alloy, the length is less than 50 μm. The mild-to-severe wear transition occurs with increasing the load, and the critical loads reduce with rising the ambient temperature for the three aluminum alloys. The changing trend of wear curves of three alloys is similar at room temperature, but the critical loads of wear transition reduce after the modification and alloying at high ambient temperatures. The refinement of primary and eutectic Si phase obviously increases the alloy performance, especially the wear resistance at elevated temperature. This is attributed to the refined Si phase avoiding the stress concentration and direct fragmentation during wear process. And mechanical mixed layer is very easy to form in the elevated temperature wear process, which hinders the direct contact between the alloy and the counterface and decreases the wear rate.
Key words: hypereutectic Al-Si alloy; modification; alloying; friction; wear
