Severe wear of a near eutectic aluminium-silicon alloy
Severe wear of a near eutectic aluminium-silicon alloy
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DOI：
10.1016/j.actamat.2011.06.016
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发表时间：
2011-09
期刊：
影响因子：
9.4
通讯作者：
A. Mahato;N. Verma;V. Jayaram;S. K. Biswas
中科院分区：
文献类型：
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作者：
A. Mahato;N. Verma;V. Jayaram;S. K. Biswas
利用电子显微镜、光谱学和衍射技术对近共晶铝硅合金的严重磨损进行了研究，以确定残余应变区和非应变区、微裂纹和地下氧化区。在严重磨损时，接触压力超过弹性安定极限。在此条件下，初生和共晶硅颗粒破碎严重。碎片是由基体运输，因为它经历了增量应变与每个循环接触在粗糙水平。晶粒从主体的~ 2000nm细化到近表面区域的30nm。与较温和磨损阶段相比，颗粒间距离的大幅度减小产生了高应变梯度，这有助于位错密度的增强。在再结晶晶粒边界和亚晶粒内部产生的极高应变区域导致微孔洞/裂纹的形成。由于氧的扩散增强，在这些地下界面处形成脆性氧化物。我们认为，由严重塑性变形引起的近表面微裂纹的丰富程度是区分严重磨损和轻度磨损的原因。
The severe wear of a near eutectic aluminium–silicon alloy is explored using a range of electron microscopic, spectroscopic and diffraction techniques to identify the residually strained and unstrained regions, microcracks and oxidized regions in the subsurface. In severe wear the contact pressure exceeds the elastic shakedown limit. Under this condition the primary and eutectic silicon particles fragment drastically. The fragments are transported by the matrix as it undergoes incremental straining with each cyclic contact at the asperity level. The grains are refined from ∼2000nm in the bulk to 30nm in the near surface region. A large reduction in the interparticle distance compared with that for a milder stage of wear gives rise to high strain gradients which contribute to an enhancement of the dislocation density. The resulting regions of very high strain in the boundaries of the recrystallized grains as well as within the subgrains lead to the formation of microvoids/cracks. This is accompanied by the formation of brittle oxides at these subsurface interfaces due to enhanced diffusion of oxygen. We believe that the abundance of such microcracks in the near surface region, primed by severe plastic deformation, is what distinguishes a severe wear regime from mild wear.