高纯难熔金属及其合金单晶的发展-中国材料进展

文章信息/Info

Title:: The development of single crystals of high-purity refractory metals and alloys

Author(s):: LI Laiping; HU Zhongwu; YIN Tao; ZHANG Wen; GAO Xuanqiao; GUO Linjiang; REN Guangpeng; ZHANG Pingxiang; LI Zhongkui; Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China

摘要:: 本文主要介绍了难熔金属及其合金单晶的制备技术，对电子书悬浮区域熔炼技术和等离子弧熔炼技术进行了比较。电子束悬浮区域熔炼法温度梯度易于控制、材料不受坩埚材料污染，但熔体表面张力对活性杂质和温度梯度敏感性高，所能制备的高纯难熔金属及其单晶材料尺寸规格受到很大限制，且材料内部位错密度较高。等离子弧熔炼法加热源能量密度高，原料规格形式多样，可制备单晶棒材、板材、管材及其他特定形状的单晶铸件，可最大程度地去除杂质元素（尤其是碳元素），但设备系统复杂，单晶材料位错密度大。本文还讨论了单晶材料发展现状，通过固溶强化可进一步提高材料的高温性能及其稳定性。单晶管材的制备也是一个发展方向。此外论文还对单晶材料制备技术和发展前景提出了一些建议。

Abstract:: In this letter, we report the processing technology of single crystals of high-purity refractory metals and alloys, and compare the electron-beam floating zone melting(EBFZM) with the plasma arc melting(PAM). By EBFZM, the temperature gradient could be controlled easily and the contamination by crucible materials is avoided, whereas the surface tension of melt is sensitive to the active impurity content and the temperature gradient. Furthermore, the dimensions of high-purity refractory metals and the monocrystalline materials are severely limited and the dislocation density in the materials is relatively high. PAM has the advantages such as high energy density of heating and various specifications of raw materials, by which the single crystal castings could be processed in the shape of rod, plate, tube and other specific shapes. Meanwhile, the impurity elements (especially carbon) are maximally removed. However, the equipment is complex and the dislocation density is high. We also discuss the status of development for single crystal materials, such as improving the resistance to high temperature and stablilty by solid-solution strengthening. The processing of single crystal tubes is also an interesting topic. We make some suggestions on the processing technology and developing prospect for single crystals of refractory metals and alloys.