1 100℃isothermal section of Nb-W-Zr-C quaternary system①
(School of Materials Science and Engineering, Central South University,
Changsha 410083, China)
Changsha 410083, China)
Abstract: An isothermal section of the Nb-W-Zr-C system at 1 100℃was established by means of multiphase diffusion couples along with electron microprobe analysis and X-ray diffraction analysis. The isothermal section consists of two single-phase regions,α(Nb, W, Zr) and (W, Nb)2Zr and one double-phase region,α(Nb, W, Zr)+(W, Nb)2Zr. It is concluded that (W, Nb)2Zr is an interstitial intermediate phase with the face-centered cubic (Cu2Mg) lattices. The maxi-
mum solid solubility of carbon in (W, Nb)2Zr phase is determined as about 4.18%C(mole fraction).The composition ranges of tungsten in the (W, Nb)2Zr phase are 55.41% to 65.98% and the maximum solid solubility of niobium in (W, Nb)2Zr is determined as 7.78%.
mum solid solubility of carbon in (W, Nb)2Zr phase is determined as about 4.18%C(mole fraction).The composition ranges of tungsten in the (W, Nb)2Zr phase are 55.41% to 65.98% and the maximum solid solubility of niobium in (W, Nb)2Zr is determined as 7.78%.
Key words: Nb-W-Zr-C quaternary system; diffusion couple; isothermal section