Mg-3Al-0.4Si镁合金的高温磨损行为研究

Wear Behavior of Mg-3Al-0.4Si Alloy at Elevated Temperatures

在20~200℃温度下,利用销盘式磨损试验机研究Mg-3Al-0.4Si合金的磨损行为,评价载荷和温度对磨损速率的影响.应用扫描电子显微镜观察磨损表面形貌以确定高温下的磨损机制,通过光学显微镜观察磨损亚表层组织演变,然后采用显微硬度计测量硬度变化.研究结果表明:随着磨损温度提高,Mg-3Al-0.4Si合金的磨损率随载荷增加而上升的趋势更为明显.其磨损行为可分为轻微和严重磨损,增加磨损温度显著降低轻微-严重磨损转变载荷.轻微-严重磨损前后的亚表层组织和硬度变化表明,摩擦热诱发磨损亚表层发生动态再结晶(DRX)组织转变引起的热软化是造成轻微-严重磨损转变的主要原因.

The wear behavior of Mg-3 Al-0.4 Si alloy at wear temperatures of 20~200 ℃ was investigated using a pin-ondisc type wear machine, in which the effects of applied load and temperature on the wear rate were presented. The morphologies of worn surfaces were observed using scanning electron microscope to determine the wear mechanisms involved. Microstructural evolution and hardness change in the subsurface were also analyzed using optical microscope and microhardness tester, respectively. The results show that as temperature increased, the increasing trend for wear rate with applied load was increasingly distinct. The wear behavior of Mg-3 Al-0.4 Si alloy was classified into the mild wear and severe wear, and increasing temperature decreased the mild-severe wear transition load. The changes of microstructure and hardness in subsurface before and after mild-severe wear transition identified the origin of mild to severe wear transition as the frictional-heating induced dynamically recrystallization（DRX） microstructure transformation and consequent softening effect in the surface layer of pin samples.