1100 ¡æ Correlation Of Nb-15w-5mo-of Zr-c Of Nb-rich Corner Of Nb-mo-zr System

First of all, the brief introduction on phase diagram and its application were given in the paper. The major methods which are used to determining phase diagram experiment were briefly assessed. Diffusion-couple along with electron probe microanalysis (EPMA) technique is a high-efficiency and precise method, at the same time the alloys method is a good complementary method.The Nb-Mo-Zr diffusion couple had been diffused for 1660 hours. The isothermal cross section of Nb-Mo-Zr was constructed by means of multiphase diffusion couples technique. There are two phases (Mo, Nb) ₂Zr and a in the Nb-Mo-Zr system at 1100℃, and there was one two-phase equilibrium: α+ (Mo, Nb) ₂Zr in this system at 1100℃.The content of Zr in the second phase (Mo,Nb)₂Zr changed from 32.19at.% to 35.03at.% while the content of Mo in it changed from 34.93at.% to 67.81at.%, and the max solid solubility of Nb in it is 30.40at.%. The Mo'max solid solubility in a phase is 8.30at.% and the Zr' is 3.09at.%. The max sum of the solid solubility of Mo and Zr in a phase is 29.75at.% which include 15.79at.%Mo and. 13.96at.%Zr.The 36 Nb based alloys were prepared in which the content of W was fixed to 15at.% and the content of Mo was fixed to 5at.% and the content of Zr changed from 0 to 4.0at.%,the content of C changed from 0 to3.0at.%. After 1440 hours' diffusion in vacuum the alloys were analyzed by means of X-ray diffraction, BSE (back scattered electrons) and EPMA (electron probe microanalysis).The phase relations of Nb-15W-5Mo-Zr-C system in the Nb-rich region at 1100℃ was obtained.There were one simple phase region, three two-phase equilibrium: α+Nb₂C,α +(Nb, Zr)C and α+(W,Mo)₂Zr, two three phase equilibrium: α+(Nb, Zr)C+Nb₂C and+(Nb, Zr)C+(W,Mo)₂Zr in the Nb-15W-5Mo-Zr-C system in the Nb-rich region at 1100℃.The max solid solubility of C in a was 0.42at. % and max solid solubility of Zr in a was 2.62at. %. In the three-phase equilibrium α(Nb)+ (Nb, Zr)C + Nb₂C the equilibrium content of a(Nb) was Nb-15.09at.%W-5.06at.%Mo-0.85at.% Zr-0.24at.%C while in the three-phase equilibrium α(Nb)+(Nb, Zr)C+(W,Mo)₂Zr the equilibrium content of a(Nb) was Nb-14.93at.%W-4.93at.%Mo-2.36at.%Zr-0.17at.%C. The W and Mo weren't found in the solid solution of (Nb, Zr)C phase, and the W, Mo and Zr weren't exit in the Nb₂C phase.There wasn't C atom exit in (W,Mo)2Zr phase.