Study of microstructure of Zr–Sn–Nb–Fe–Cr alloy in the temperature range of 750–820 °C

The microstructure of a Zr–Sn–Nb–Fe–Cr alloy was investigated by optical microscope and transmission electron microscope (TEM). Hot and cold rolling and quenching tests were carried out at the temperature of 750–820 °C. The microscopic results showed that the microstructure contained α and β phases while heating at temperatures above 780 °C, and the volume fractions of β-Zr phase at 780, 800 and 820 °C were approximately 4, 8 and 18%, respectively. The second phase particles (SPP) in samples rolled at 750 °C are distributed uniformly. However, some SPP in samples rolled at temperatures of above 780 °C existed in the form of strings and agglomerates. The most precipitates in the Zr–Sn–Nb–Fe–Cr alloy are hcp Zr(Nb,Fe)2 phase, which was similar to that of ZIRLO® and E635. In addition, there are a few fcc (Zr,Nb)2Fe phases. The microstructures in the rolled material confirmed the predictions of the processing map. These results have been discussed extensively.