Ti掺杂对CoCrCuFeMn高熵合金组织结构和耐磨性的影响

Effect of Ti Doping on Microstructure and Wear Resistance of CoCrCuFeMn High-entropy Alloys

高熵合金由于具有众多优异性能,有可能突破传统合金的性能极限,被认为是下一代金属材料的发展方向。CoCrCuFeMn作为一种重要的高熵合金体系,目前关于Ti掺杂对其组织结构与性能影响的报道较少。采用熔铸法制备等摩尔比的CoCrCuFeMn和CoCrCuFeMnTi高熵合金,利用XRD、OM、SEM、EDS、显微硬度计和摩擦磨损试验机分别测试Ti掺杂前后对其物相结构、显微组织和耐磨性的影响。结果表明,CoCrCuFeMn由FCC1和FCC2双相组成,Ti掺杂使其物相结构转变成BCC和HCP相的双相组织。两种合金均为典型的树枝晶结构,Cu元素在晶间富集,Mn元素的偏析系数最小。Ti掺杂并未改变合金元素的富集区域,但使所有元素偏析系数降低。Ti掺杂使合金的硬度从219.6HV提高到693.8HV,摩擦因数和质量损失率分别从0.57、4.14%降低到0.55、1.28%。Ti掺杂合金硬度和耐磨性的提高主要是由于相转变、固溶强化、细晶强化和内应力降低的综合作用所致。研究成果不仅有助于完善和丰富Ti元素掺杂对CoCrCuFeMn合金性能影响的相关理论,同时也为该合金后续的科学研究和工程应用提供理论支撑。

High-entropy alloys are considered as the development direction of the next-generation metal materials due to its many excellent properties, which may break through the performance limits of traditional alloys. CoCrCuFeMn is as an important high-entropy alloy system. There are few reports on the effect of Ti doping on their microstructure and properties at present. CoCrCuFeMn and CoCrCuFeMnTi high entropy alloys are fabricated by melting-casting method. The phase structure, microstructure and wear resistance for this alloy without and with Ti doping are investigated by XRD, OM, SEM, EDS, microhardness tester and friction-wear tester, respectively. The results show that CoCrCuFeMn alloy has FCC1+FCC2 dual phase structure. The phase structure transforms into BCC+HCP dual phase after Ti doping. Both alloys are typical dendrite structures. The interdendrite region is mainly Cu-rich area, and Mn has the smallest segregation coefficient. After Ti doping, the enrichment region of the alloying elements does not change, but the segregation coefficient decreases for alloy elements. The microhardness increases from 219.6 HV to 693.8 HV after Ti adding, and the average friction coefficient and the mass loss rate decrease from 0.57 and 4.14% to 0.55 and 1.28%, respectively. The improvement of hardness and wear resistance for Ti doping alloy is mainly due to the combined effects of phase transformation, solid solution strengthening, fine grain strengthening and lower internal stress. The research results not only help to improve and enrich the related theory of Ti doping on the properties of CoCrCuFeMn alloy, but also provide theoretical support for their subsequent scientific research and engineering application.