激光熔覆AlCoCrFeNi/WC高熵合金梯度复合涂层的组织与摩擦学性能研究

Microstructure and Tribological Properties of Laser Cladding AlCoCrFeNi/WC High Entropy Alloy Gradient Composite Coatings

摘要:

为提高金属部件表面耐磨性，本研究通过定量分析WC陶瓷颗粒含量对AlCoCrFeNi高熵合金梯度涂层微观结构演变及其力学性能增强机制的影响，利用激光熔覆技术在45#钢基板上制备了致密且均匀的不同WC含量的AlCoCrFeNi高熵合金梯度复合涂层。实验结果表明，随着WC含量的增加，涂层的晶粒尺寸显著细化，从20.16 μm降低至7.71 μm，晶粒形状从胞状晶转变为树枝晶和等轴晶。梯度复合涂层的显微硬度提高为基材的3倍，相较于未添加WC的高熵涂层提升了1.4倍。涂层结构主要包括体心立方相和金属碳化物，且随着WC含量的提升，相应的衍射峰强度逐渐增大。磨损性能测试结果显示，在WC含量为20wt%时涂层表现出最优的耐磨性能，其摩擦系数和磨损量分别是0.4680和0.16 mg，均低于平均硬度最高的WC含量为40wt%的涂层，表明在提高涂层硬度的同时保持适当的韧性是实现涂层性能优化的关键。本研究为激光熔覆制备高熵合金涂层性能优化和推广应用提供了新思路。

Abstract:

Dense and uniform high-entropy alloy AlCoCrFeNi gradient composite coating with different WC content was prepared on 45# steel substrate by laser cladding technology. The effect of ceramic particle content on the microstructure evolution and mechanical properties enhancement mechanism of high-entropy alloy gradient coating was quantitatively analyzed in order to improve the surface wear resistance of metal parts. The results show that with the increase in WC content, the grain size of the coating decreases from 20.16 μm to 7.71 μm, and the grain shape changes from cellular to dendrite and equiaxed. In addition, the microhardness of the gradient composite coating is significantly increased, which is 3 times that of the substrate, and 1.4 times higher than that of the high-entropy coating without adding WC. The coating mainly consists of body-centered cubic phase and metal carbide, and the corresponding diffraction peak intensity increases gradually with the increase in WC content. The wear performance test results show that the coating exhibits the best wear resistance when the WC content is 20wt%, and the friction coefficient and wear amount are 0.4680 and 0.16 mg, respectively, which are lower than the coating with 40%wt WC which has the highest average hardness, indicating that maintaining appropriate toughness while improving the hardness of the coating is the key to achieve the optimization of the coating performance. This study provides a certain reference value for the study of the optimization of high entropy alloy coatings prepared by laser cladding.