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机械合金化结合激光熔覆技术制备CoCrMoNbTi难熔高熵合金

CoCrMoNbTi refractory high-entropy alloys prepared by mechanical alloying combined with laser cladding

  • 摘要: 采用机械合金化方法制备CoCrMoNbTi难熔高熵合金粉末,并通过激光熔覆技术成功制备出CoCrMoNbTi高熵合金涂层。研究了球磨时间对合金粉末组织形貌的影响,并利用X射线衍射仪、扫描电子显微镜和能谱仪等分析了高熵合金粉末和涂层的微观结构。结果表明,随着球磨时间的增加,单质金属的衍射峰按其熔点由低到高陆续消失。粉末微观形貌随球磨时间变化明显,粉末由原始状态被挤压成片状,片状粉末逐渐焊合在一起形成扁平状粉末颗粒。在球磨时间达到40 h时,粉末实现完全合金化,此时粉末形貌趋于球形且得到了极大的细化,粉末中各元素分布均匀,形成了稳定的单相体心立方固溶体结构。CoCrMoNbTi难熔高熵合金激光熔覆层成形质量良好,主要由体心立方固溶体和少量Cr2Nb、Co2Ti化合物组成,树枝晶组织细小致密。

     

    Abstract: CoCrMoNbTi refractory high-entropy alloy powders were prepared by mechanical alloying, and the CoCrMoNbTi high-entropy alloy coatings were successfully prepared by laser cladding technology. The influence of ball milling time on the phase composition and microstructure of the CoCrMoNbTi refractory high-entropy alloy powders and coatings were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrum (EDS) analysis. The results show that, with the increase of milling time, the diffraction peak of the pure metal phase gradually disappears, which is mainly related to the melting point of the alloying element. In addition, the powder morphology changes significantly with the extension of milling time. The powders are extruded from the original state into the flake, and the flake powders are gradually welded together to form the flat powder particles. When the milling time reaches 40 h, the powders are completely alloyed, the powder shape tends to be spherical and greatly refined, and the elements in the powders are evenly distributed, forming a stable single-phase body-centered cubic solid solution structure. The CoCrMoNbTi refractory high entropy alloy coatings prepared by laser cladding technology have the good forming quality. The coatings are mainly composed of the body-centered cubic solid solution structure and a small amount of Cr2Nb and Co2Ti compounds, forming a fine and compact dendritic structure.

     

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