ISSN   1004-0595

CN  62-1224/O4

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单相CoCrFeNi与两相AlCoCrFeNi高熵合金在3.5% NaCl溶液中的腐蚀磨损行为研究

Tribo-Corrosion Behaviors of Single-Phase CoCrFeNi and Two-Phase AlCoCrFeNi High Entropy Alloys in 3.5% NaCl Solution

  • 摘要: 高熵合金以其独特的多主元固溶体结构特征,能够兼具有优异的耐蚀性和耐磨性,在海洋工程领域具有重要应用前景. 本文中系统研究了CoCrFeNi和AlCoCrFeNi高熵合金在质量分数为3.5%的NaCl溶液中的腐蚀磨损性能,选择304不锈钢作为对比合金,定量计算了腐蚀与磨损交互作用. 研究发现:CoCrFeNi合金为面心立方(FCC)相结构,AlCoCrFeNi合金为体心立方(BCC)相与有序体心立方(B2)相耦合双相结构. 相比CoCrFeNi合金,AlCoCrFeNi合金的耐腐蚀性能较差,这归因于两个方面:两相结构形成的微观腐蚀电池;Al元素与Cr元素在腐蚀过程中竞争氧原子,并且其自身化学性质更为活泼,减少了钝化层Cr2O3的含量. 相比静态纯腐蚀条件,动态腐蚀磨损条件加剧了CoCrFeNi和AlCoCrFeNi高熵合金的腐蚀行为. 在阴极保护的纯磨损工况下,归因于固溶强化作用,CoCrFeNi和AlCoCrFeNi高熵合金表现出优于304不锈钢的高硬度和抗磨损性能;BCC/B2相耦合AlCoCrFeNi合金表现出最高的硬度和最优异的抗磨损性能. 在腐蚀磨损工况下,腐蚀加剧了合金的磨损行为;耐蚀性最佳、硬度适中的CoCrFeNi合金表现出最低的ΔWC (因腐蚀而导致摩擦速率增量),耐蚀性较差的AlCoCrFeNi合金和硬度较低的304不锈钢表现出较高的ΔWC. CoCrFeNi、AlCoCrFeNi高熵合金和304不锈钢的ΔWc/W0 (纯磨损速率)值均低于1,在腐蚀磨损过程中的材料损失主要受磨损的影响.

     

    Abstract: The tribo-corrosion behavior in a seawater environment represents a significant challenge in the marine engineering and marine equipment field. The interaction of wear and corrosion can result in the premature failure of moving parts in a seawater environment. It is therefore imperative to enhance the tribo-corrosion resistance of moving parts in seawater. High-entropy alloys with their distinctive multi-major element solid solution structure exhibit remarkable corrosion and wear resistance, offering significant potential for application in marine engineering. The development of high-entropy alloys with excellent corrosion and wear resistance must address the following issues: (1) the composition, organization, structure of the alloy and their impact on corrosion and wear resistance. Typical high-entropy alloy matrix organization includes single-phase solid solution and two-phase composite structure, with the matrix structure comprising Face-Centered Cubic (FCC) phase and Body-Centered Cubic (BCC) phase. (2) Providing a detailed account of the tribo-corrosion behavior of the alloy, including the role of wear on corrosion behavior and the role of corrosion on wear behavior. Considering the considerations, this paper presented a comprehensive investigation into the tribo-corrosion performance of CoCrFeNi and AlCoCrFeNi high-entropy alloys in a 3.5% NaCl solution. To provide a point of comparison, 304 stainless steel was selected for analysis. The corrosion and wear interaction was then quantified through a systematic approach. It was determined that the CoCrFeNi alloy possessed an FCC phase structure, whereas the AlCoCrFeNi alloy exhibited a BCC/ Body-Centered Cubic Ordering Phase 2 (B2) phase coupled two-phase structure. The inferior corrosion resistance of the AlCoCrFeNi alloy in comparison to the CoCrFeNi alloy could be attributed to two factors: firstly, the formation of a microscopic corrosion cell within the two-phase structure; secondly, Aluminum (Al) and chromium (Cr) elements competed for oxygen atoms during the corrosion process. Moreover, the chemical property of aluminum itself was more reactive, which reduced the content of the passive layer Cr2O3. The dynamic frictional corrosion conditions resulted in more pronounced corrosion behavior of the CoCrFeNi and AlCoCrFeNi high-entropy alloys in comparison to the static pure conditions. In pure wear conditions with cathodic protection, both CoCrFeNi and AlCoCrFeNi high-entropy alloys demonstrated superior hardness and wear resistance compared to 304 stainless steel, attributable to solid-solution strengthening. The BCC/B2 coupled AlCoCrFeNi alloy exhibited the highest hardness and excellent wear resistance. Under tribo-corrosion conditions, corrosion exacerbated the wear behavior of the alloys. The CoCrFeNi alloy, with the best corrosion resistance and moderate hardness, showed the lowest ΔWC (increase in friction rate due to corrosion). While the AlCoCrFeNi alloy with poorer corrosion resistance, and the 304 stainless steel with lower hardness, exhibiting higher ΔWC values. The ΔWC/W0 (Pure wear rate) ratios of CoCrFeNi, AlCoCrFeNi high-entropy alloys and 304 stainless steel were all below 1, indicating that material loss during the tribo-corrosion process was primarily influenced by wear.

     

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