Abstract:The precipitates and phase the transformation temperatures of both zirconium alloys, Zr-1Sn-0.3Nb-0.3Fe-0.1Cr alloy and Zr-0.8Sn-0.3Nb-0.3Fe-0.1Cr alloy were investigated. The temperatures of the phase transformation of both zirconium alloys were measured by Differential Scanning Calorimetric (DSC). The effect of Sn content on the phase transformation temperature was studied. The microstructures of the alloy specimens as 6 processed states (as hot rolled state, as hot rolled+annealed state, as cold rolled state, as cold rolled+annealed state, as final rolled state, and as final rolled+annealed state) were observed carefully by SEM, Then the sizes and the volume fractions and their distributions of the second precipitated phase in the alloys were analyzed and calculated by quantitative metallography and Energy Dispersive Spectrum (EDS). The results show that the decrease of Sn content has a obvious influence on the phase trasformation temperature of α→β, and very little effect on the spape and the structure of the precipitated particles, but their average sizes will be reduced. EDS results show that the segregation of Sn content exists in the Zr alloy to some extent.