| Zr, Cu, Cr, Fe and Sn are important alloying element of the Zirconium alloys. In recent years, Cu element attracted much attention as an important additional zirconium alloy elements for its effective improvement of corrosion resistance of zirconium alloy. The knowledge for the interaction of Cu and the other alloying elements, would explain phase transition of the Zirconium alloy, and control second-phase paticles precipitation. In this work, the isothermal sections of the Zr-Cr-Cu and Zr-Fe-Cu ternary systems at 700℃ were investigated by using X-ray diffraction, scanning electron microscope and energy dispersive analysis. Moreover, a further research on the isothermal section of the (Zr-1.5Sn)-Fe-Cu pseudo-ternary system at 700℃ in the Zr-rich corner was carried out. Some important results are listed as follow,(1) The isothermal section of the Zr-Cr-Cu ternary system at 700℃ has been established. It is composed of 9 three-phase regions,18 two-phase regions and 10 single-phase regions. The τ phase was observed to occur as a stable ternary phase at 700℃ when Cr was introduced. No ternary compound was observed in the Zr-rich corner and Cu-rich corner. The alloys in Zr-rich corner is consists of ZrCr2, (a-Zr) and CuZr2, while those in the Cu-rich corner is consists of (Cr), (Cu) and(2) The isothermal section of the Zr-Fe-Cu ternary system at 700℃ has been established. Two Zr-Fe-Cu ternary phase, Zr(Fe,Cu) and Zr2(Fe,Cu), named τ1 and τ2, have been found in this section. There have nine binary phase, Fe2Zr, FeZr3, CuZr2, Cu10Zr7, CugZr3, Cu51Zr14 and Cu5Zr, were stable at this temperature. Large amount of Fe was found to solute in Cu51Zr14, the solubility of Fe in Cu51Zr14 is 18.6%. In addition, the oxygen stablilized phase Fe23Zr6 wasn’t observed in Zr-Fe-Cu ternary system.(3) The isothermal section of (Zr-1.5Sn)-Fe-Cu pseudo-ternary system at 700℃ for Zr-rich corner has been established. There are four ternary phases, τ1, τ2,9 and τ3, have been found in this section. The new ternary phase τ3 belong to Zr-Sn-Cu ternary system, with an approximate composition ratio of Zr:Sn:Cu=5: 2:3. Four quaternary-phase regions in Zr-rich corner were evidenced by equilibrated alloys. The obtained isothermal section of (Zr-1.5Sn)-Fe-Cu pseudo-ternary is compatible with the Zr-Fe-Cu and Zr-Sn-Fe ternary systems. Because of the lack of the precise information on Zr-Sn-Cu ternary system, the details of τ3 in Zr-Sn-Cu ternary system are needed further investigation. |
