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
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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Δ WC。 CoCrFeNi、 AlCoCrFeNi 高熵合金和 304 不锈钢的Δ Wc/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。
High-entropy alloys (HEAs), characterized by their unique multi-principal element solid solution structures, exhibit both excellent corrosion resistance and wear resistance, holding significant application prospects in the field of marine engineering. In this study, the corrosion-wear properties of CoCrFeNi and AlCoCrFeNi high-entropy alloys were systematically investigated in a 3.5% mass fraction NaCl solution, with 304 stainless steel selected as the control alloy. The synergistic interaction between corrosion and wear was quantitatively calculated. It is found that: CoCrFeNi alloy has a face-centered cubic (FCC) phase structure, while AlCoCrFeNi alloy has a dual-phase structure composed of body-centered cubic (BCC) and ordered body-centered cubic (B2) phases. Compared with CoCrFeNi alloy, AlCoCrFeNi alloy exhibits poorer corrosion resistance, which can be attributed to two aspects: the microscopic galvanic cells formed by the dual-phase structure; and the competition for oxygen atoms between Al and Cr elements during the corrosion process, with Al's higher chemical activity reducing the content of the passivation layer Cr₂O₃. Compared to static pure corrosion conditions, dynamic corrosion-wear conditions exacerbate the corrosion behavior of CoCrFeNi and AlCoCrFeNi high-entropy alloys. Under pure wear conditions with cathodic protection, CoCrFeNi and AlCoCrFeNi high-entropy alloys show higher hardness and better wear resistance than 304 stainless steel, which is attributed to solid solution strengthening. Among them, the BCC/B2 phase-coupled AlCoCrFeNi alloy has the highest hardness and the most excellent wear resistance. Under corrosion-wear conditions, corrosion aggravates the wear behavior of the alloys. CoCrFeNi alloy, which has the best corrosion resistance and moderate hardness, exhibits the lowest ΔWC (increment of wear rate caused by corrosion). In contrast, AlCoCrFeNi alloy with poor corrosion resistance and 304 stainless steel with low hardness show higher ΔWC. The ΔWc/W0 (ratio of corrosion-induced wear rate increment to pure wear rate) values of CoCrFeNi, AlCoCrFeNi high-entropy alloys and 304 stainless steel are all lower than 1, indicating that the material loss during the corrosion-wear process is mainly dominated by wear.
