Intermetallics and phase transformations of the Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr alloy

Intermetallics and phase transformations of the zirconium-based alloy, Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr, were investigated by conventional X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dilation measurement. Three types of precipitates, namely, (ZrNb)2Fe, Zr(CrFe)2, and Zr3Fe, were detected by XRD. The cubic Ti2Ni-type (ZrNb)2Fe was found to be the main precipitate in the alloy, and it was proposed to dissolve at 861°C, whereas Zr3Fe dissolved at 780°C and Zr(CrFe)2 at 814°C. No precipitates were observed at a temperature higher than 900°C. The transformation-start temperature of α-Zr → β-Zr was reconfirmed to be 780°C, and the end temperature of α-Zr → β-Zr was determined to be 955°C. The dilation result also revealed that the martensitic transformation-start temperature, Ms, and the finish temperature, Mf, of this alloy were 741°C and 645°C, respectively.