Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China
Keywords:
-
CLC:
PACS:
-
DOI:
10.7502/j.issn.1674-3962.2014.09.04
DocumentCode:
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.