ISSN   1004-0595

CN  62-1224/O4

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近单一FCC相AlCoCrFeNi高熵合金的常温摩擦学行为及典型磨损机制

Tribological Behaviors and Typical Wear Mechanisms of Nearly Single FCC Phase AlCoCrFeNi High-Entropy Alloy at Ambient Temperature

  • 摘要: 采用SRV-Ⅳ型微动摩擦磨损试验机对近单一面心立方(FCC)相AlCoCrFeNi高熵合金及其抛丸试样在常温下的摩擦磨损性能和行为进行了较详细的考察. AlCoCrFeNi高熵合金的磨损量随摩擦频率和法向载荷的变化均大体呈现正相关性. 随着摩擦频率升高(6~40 Hz),该高熵合金摩擦界面的原子排列由主要沿(100)晶面逐渐转变为沿(111)晶面,表现出显著的择优取向,其主要磨损机制由氧化磨损和分层磨损逐步过渡到塑性变形和分层磨损;拉曼光谱分析表明该合金在各摩擦频率(除30 Hz外)下形成的磨痕中存在复杂氧化物,其结晶构造与Al2O3和Cr2O3相似. 随着法向载荷不断增大(10~200 N),该合金摩擦界面的晶粒更加细化,摩擦界面的原子排列更加趋向沿(111)晶面,其主要磨损机制由氧化磨损过渡到疲劳磨损,最终转变为黏着磨损. 由于细晶强化作用,经抛丸处理后该AlCoCrFeNi高熵合金表面显微硬度达403 HV,相比抛丸前提高近1倍. 抛丸处理形成的表面强化层有利于降低合金的磨损,其厚度约为25 μm. 随着摩擦时间延长,该高熵合金抛丸试样的主导磨损机制由塑性变形和分层磨损逐渐转变为同时出现一定程度的氧化磨损;其中,塑性变形和分层磨损机制的组合能导致该合金抛丸试样发生零磨损行为. 近单一FCC相AlCoCrFeNi高熵合金及其抛丸试样因其特殊的元素组成和原子排布表现出丰富而典型的磨损行为和机制. 本研究阐明了该高熵合金在常温下的几种典型磨损机制,评估抛丸处理对其造成的实际影响,为该体系高熵合金和含有FCC相的复合结构高熵合金在磨损防护领域的合理运用及深入理解其使役行为提供重要依据.

     

    Abstract: The friction and wear properties and behaviors of nearly single face-centered cubic (FCC) phase AlCoCrFeNi high-entropy alloy and its shot-blasting samples at ambient temperature were investigated in detail by SRV-IV micro-vibration friction and wear testing machine. The variation in the wear of the AlCoCrFeNi high-entropy alloy showed a positive correlation with both friction frequency and normal load. With the increase of friction frequency (6~40 Hz), the atomic arrangement of the friction interface of the high-entropy alloy gradually changed from mainly along (100) crystal plane to along (111) plane, showing a significant preferred orientation, and the main wear mechanism of the high-entropy alloy gradually varied from oxidative and delamination wear to plastic deformation and delamination wear. Raman spectrum analysis showed that complex oxides exist in the wear tracks formed at all the tested friction frequencies except 30 Hz, and their crystalline structures were similar to Al2O3 and Cr2O3. With the increase of normal load (10~200 N), the crystalline grains at the friction interface of the alloy became finer, and the atomic arrangement of the friction interface tended to be along (111) plane. The dominant wear mechanism of the alloy changed from oxidative wear to fatigue wear, and finally to adhesive wear. Due to the strengthening effect of fine grains, the surface micro-hardness of the AlCoCrFeNi high-entropy alloy after shot blasting was up to 403 HV, which was nearly twice as high as that before shot blasting. The surface strengthening layer formed by shot blasting treatment would reduce the wear of the alloy, and its thickness was about 25 μm. With the increase of friction time, the primary wear mechanism of the high-entropy alloy shot-blasting specimens gradually changed from plastic deformation and delamination wear to simultaneous oxidative wear (in some extent); the combination of plastic deformation and delamination wear mechanism would lead to the fantastic zero wear behavior of the alloy shot-blasting sample. The nearly single FCC phase AlCoCrFeNi high-entropy alloy and its shot-blasting samples revealed various and typical wear behaviors and mechanisms for special element composition and atomic arrangement. In this study, several typical wear mechanisms of the high-entropy alloy at ambient temperature were clarified, and the actual impact of shot blasting on it was evaluated. This work provides important basis for the rational application of the high-entropy alloy system and the composite structure high-entropy alloys containing FCC phase in the field of wear protection and in-depth understanding of their service behaviors.

     

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