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工程科学与技术:2021,53(6):204-210
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Zr元素对CoCrCuFeMn高熵合金组织及耐磨性能的影响
(1.中原工学院 材料与化工学院,河南 郑州 450007;2.四川大学 材料科学与工程学院,四川 成都 610065)
Effect of Zr Addition on Microstructure and Wear Properties of CoCrCuFeMn High-entropy Alloy
(1.School of Materials and Chemical Eng., Zhongyuan Univ. of Technol., Zhengzhou 450007, China;2.School of Materials Sci. and Eng., Sichuan Univ., Chengdu 610065, China)
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投稿时间:2021-01-18    修订日期:2021-05-12
中文摘要: 高熵合金突破以1种或2种元素作为基元的传统合金设计理念,以等摩尔比或近等摩尔比制备出具有简单相结构且综合性能优异的多主元合金,有望使金属材料的性能极限和应用空间得到进一步拓展。为了研究元素掺杂对合金物相结构、显微组织和耐磨性能的影响机理,采用真空熔炼法制备出等摩尔比的CoCrCuFeMn和CoCrCuFeMnZr高熵合金。利用XRD、OM、SEM、EDS、显微硬度计和摩擦磨损试验机测试了Zr元素添加前后CoCrCuFeMn合金的物相结构、显微组织、硬度和耐磨性。研究发现:添加Zr元素后,CoCrCuFeMnZr合金的物相结构由原来的2种FCC相转变为2种HCP相,显微组织明显细化,仍为典型的树枝晶结构。2种合金的摩擦曲线都呈现先增大后降低再稳定的变化趋势;添加Zr元素后合金的摩擦因数与质量损失率分别从原来的0.57、4.14%降低到0.47、0.49%,显微硬度从219.6 HV提高到983.5 HV。结果表明:合金相结构发生HCP转变主要与凝固过程中易于形成富含大原子半径Zr元素的粗糙固液界面和“之”字型为主的HCP位向关系有关。Cu在晶间区域富集的原因在于其熔点最低、电负性最大、原子半径仅次于Zr,且与除Zr外的所有合金元素均具有相应最大的正混合焓,故使其在凝固最晚的晶间区域聚集。Mn元素偏析系数最小是由于其熔点仅高于Cu和具有除Zr外最大的电负性差,且与Co和Zr之间存在负的混合焓,与Cu之间具有最大正混合焓,不利于其进行长程扩散和进入领先相的点阵格位所致。Zr元素添加使合金硬度和耐磨性大幅提高,是由于细晶强化、固溶强化和相结构转变所致。
Abstract:High entropy alloys break through the traditional alloy design concept with one or two elements as basic elements, and have a simple phase structure and excellent comprehensive performance prepared by equimolar ratio or near equimolar ratio, which is expected to further expand the performance limit and application of metal materials. In order to study the effect of element doping on phase structure, microstructure and wear resistance, CoCrCuFeMn and CoCrCuFeMnZr high entropy alloys with equal molar ratio were prepared by vacuum melting method. The phase structure, microstructure, hardness and wear resistance of CoCrCuFeMn alloy before and after Zr addition were investigated by XRD, OM, SEM, EDS, microhardness tester and friction-wear tester. It was found that after Zr addition, the phase structure of CoCrCuFeMnZr alloy was changed from the original two FCC phases to two HCP phases, and the microstructure was obviously refined. The two alloys were typical dendrite structure. The friction curves of the two alloys showed a trend of first increasing, then decreasing, and then stabilizing. After Zr addition, the friction coefficient and mass loss rate decreased from 0.57 and 4.14% to 0.47 and 0.49% respectively, and the microhardness increased from 219.6 HV to 983.5 HV. The results showed that the HCP transformation of alloy phase structure was mainly related to the formation of a rough solid-liquid interface rich in Zr with large atomic radius and Z-shaped HCP orientation. The reason why Cu is enriched in the interdendrite region is that its melting point is the lowest, its electronegativity is the largest, its atomic radius is second only to Zr, and it has the corresponding largest positive mixing enthalpy with all alloy elements except Zr, so it is enriched in the interdendrite region with the latest solidification. Due to the fact that the melting point of Mn is only higher than that of Cu, Mn has the largest electronegativity difference except Zr, and there is a negative mixing enthalpy between Mn and Co or Zr and the largest positive mixing enthalpy between Mn and Cu, which is not conducive to its long-range diffusion and entering into the lattice site of the leading phase, the segregation coefficient of Mn is the smallest. The increase of hardness and wear resistance of the alloy with Zr element is due to fine grain strengthening, solid solution strengthening and phase structure transformation.
文章编号:202100067     中图分类号:TH142.2    文献标志码:
基金项目:国家自然科学基金项目(51271115);河南省高等学校重点科研项目(20B430022);中国纺织工业联合会科技指导性项目 (2020029);河南省高校省级大学生创新创业训练计划(S202010465030)
作者简介:第一作者:马明星(1984-),男,副教授,博士.研究方向:多主元高熵合金;稀土发光材料.E-mail:manager92@163.com;通信作者:王志新,E-mail:zxwang72@163.com
引用文本:
马明星,朱达川,王志新,李尚之,董晨.Zr元素对CoCrCuFeMn高熵合金组织及耐磨性能的影响[J].工程科学与技术,2021,53(6):204-210.
MA Mingxing,ZHU Dachuan,WANG Zhixin,LI Shangzhi,DONG Chen.Effect of Zr Addition on Microstructure and Wear Properties of CoCrCuFeMn High-entropy Alloy[J].Advanced Engineering Sciences,2021,53(6):204-210.