ABSTRACT The effect of thermal exposure on the elevated-temperature mechanical properties of heat-treated Al-12Si-4Cu-1Ni-1 Mg-2Mn piston alloys was investigated using optical microscopy (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM), and tensile tests at elevated temperatures. The results showed that coarsening of the strengthening precipitates following a prolonged exposure at 350°C had a deleterious effect on the elevated-temperature tensile properties. Further thermal exposure up to 50 h did not result in even a slight reduction in the strength. After exposure at 350°C, the value of elevated-temperature ultimate tensile strengths of Al-12Si-4Cu-1Ni-1 Mg-2Mn piston alloys were 92, 80, and 73 MPa for 0 h, 10 h, and 100 h of thermal exposure, respectively, which are superior to those of the commercial piston alloys. The high-performance, elevated-temperature mechanical properties of Al-12Si-4Cu-1Ni-1 Mg-2Mn piston alloys can be attributed to the high thermal stability Mn-rich intermetallics and Al3CuNi.

中文翻译：

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热暴露对Al-12Si-4Cu-1Ni-1Mg-2Mn活塞合金组织和力学性能的影响

摘要 使用光学显微镜 (OM)、扫描电子显微镜 (SEM)、透射电子显微镜研究了热暴露对热处理后的 Al-12Si-4Cu-1Ni-1 Mg-2Mn 活塞合金的高温力学性能的影响(TEM) 和高温拉伸试验。结果表明，在 350°C 下长时间暴露后强化析出物的粗化对高温拉伸性能有不利影响。长达 50 小时的进一步热暴露甚至不会导致强度的轻微降低。在 350°C 下暴露后，Al-12Si-4Cu-1Ni-1 Mg-2Mn 活塞合金的高温极限拉伸强度分别为 92、80 和 73 MPa，分别为 0 h、10 h 和 100 h。热暴露分别为 优于商业活塞合金。Al-12Si-4Cu-1Ni-1 Mg-2Mn 活塞合金的高性能、高温机械性能可归因于高热稳定性的富锰金属间化合物和 Al3CuNi。