Isothermal Sections Of Zr-Sn-Nb-Fe-Cu Multi-Element Alloys

Zr, Fe, Cu, Nb and Sn are widely used in structure material of nuclear reactor. Zr-Nb alloys has attracted great attention in the industry application, for their lower costs, fuel efficiency and safety. The alloy phase diagrams play a key role in in the significant to guide for the performance and application of new materials. The isothermal section of the Zr-Cu-Sn ternary system at 800℃, that of the Zr-Sn-Fe ternary system at 580℃ and that of Zr-Nb-Cu ternary system at 800℃, were investigated by X-ray diffraction analysis (XRD) and scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX) techniques. In addition, the Zr-Fe-Cu-Nb quaternary system at 700℃ for the Zr-rich corner was studied too. Some important results are listed as follow:(1) The isothermal section of the Zr-Cu-Sn ternary system at 800℃ has been established. It is composed of 16 single-phase regions,21 two phase-regions and 13 three-phase regions. A new ternary compound τ(Zr24.9Cu67.2Sn7.9) was observed in the Cu-rich conner of this system. The existence of CuZrSn ternary compound was Confirmed. CuZrSn2 ternary phase has been entered in solid liquid phase area at 800℃, and isn’t observed in this experiment.(2) The isothermal section of the Zr-Sn-Fe ternary system at 580℃ was established. It is consisted of 14 single-phase regions,26 two-phase regions and 17 three-phase regions. The existence of Y, X and N phases were confirmed.The high temperature FeZr2 phase was observed to be stable at 580℃. The solid solubility of Fe2Zr was observed to increase with the decreasing of the temperature.(3) The isothermal section of the Zr-Nb-Fe ternary system at 800℃ was established. The maximum solubility of Nb in CuZr2 was 4.9 at.%. The maximum solubility of Zr and Cu in (Nb) was 22.0 at.% and 5.6 at.%. The maximum solubility of Nb and Cu in βZr was 36.2 at.% and 3.5 at.%.(4) It is confirmed the Zr-Fe-Cu-Nb quaternary system in the Zr-rich that exist five quaternary phase system. By adding a small amount of Nb at the aZr+τ2+CuZr2 phase area, the βZr+λ1+CuZr2 phase area was found in the Zr-Fe-Cu ternary system. By adding a small amount of Fe at the βZr+aZr+CuZr2 phase area, the βZr+aZr+CuZr2+λ1 phase area was found in the Zr-Nb-Cu ternary system. By adding a small amount of Cu at the βZr+λ1+λ2 phase area, the βZr+λ1+λ2 and βZr+λ1+CuZr2 phase area were found in the Zr-Nb-Fe ternary system. By adding a small amount of Cu at the βZr+λ2+(Nb) phase area, the aZr+λ1+CuZr2 phase area was found in the Zr-Nb-Fe ternary system.