Mo含量对NbTiZrMox难熔高熵合金微观组织、耐磨性和腐蚀行为的影响

Influence of Mo Content on Microstructure, Wear Resistance, and Corrosion Behavior of NbTiZrMox Refractory High-Entropy Alloys

摘要:

以高纯度的Nb、Ti、Zr、Mo颗粒为原料，采用真空电弧炉制备了不同Mo含量的NbTiZrMo_x难熔高熵合金。系统探讨了Mo元素在合金中的作用，以及不同Mo含量对合金的微观组织、显微硬度、耐腐蚀性和耐磨性的影响。结果表明，NbTiZrMo_x合金具有单一的体心立方相结构，呈枝晶形貌。Mo通过晶粒细化和固溶强化显著提高了合金的显微硬度与耐磨性。随着Mo含量的增加，合金的磨损机制由以黏着磨损为主导、磨粒磨损与氧化磨损共同作用逐渐转变为氧化磨损和轻微的黏着磨损。在3.5wt% NaCl溶液中的电化学腐蚀测试表明，NbTiZrMo_x合金的耐腐蚀性随Mo含量增加呈先增强后减弱的规律，其中Mo含量为14.29at%时，合金的耐腐蚀性最佳，表明适量添加Mo能够促进稳定钝化膜的形成，从而显著提高合金的耐腐蚀性能。

Abstract:

NbTiZrMo_x alloys were prepared by vacuum arc furnace with high-purity powder mixtures of Nb, Ti, Zr, and Mo as raw materials. The role of element Mo in NbTiZrMo_x alloys and the effect of different Mo content on microstructure, microhardness, wear resistance, and corrosion resistance of NbTiZrMo_x alloys were investigated. Results show that these alloys display a typical dendritic morphology with a single-phase body-centered cubic crystal structure. The microhardness and wear resistance of NbTiZrMo_x alloys are significantly improved with the increase in Mo content, which is attributed to solid-solution strengthening and fine-grain strengthening. With the increase in Mo content, the dominant wear mechanism of the alloy transforms from adhesive wear accompanied by abrasive and oxidative wear to oxidative wear with slight adhesive wear. Electrochemical corrosion tests conducted in a 3.5wt% NaCl solution reveal that the corrosion resistance of NbTiZrM alloys exhibits a trend of initial enhancement followed by deterioration as Mo content rises. The alloy containing 14.29at% Mo achieves the optimal corrosion resistance, demonstrating that an appropriate addition of Mo facilitates the formation of a stable passive film and thereby markedly improves the corrosion resistance of the alloy.