Phase Transformation Temperatures and Solute Redistribution in a Quaternary Zirconium Alloy

This study investigates the phase stability and redistribution of solute during heating and cooling of a quaternary zirconium alloy, Excel (Zr-3.2Sn-0.8Mo-0.8Nb). Time-of-flight neutron diffraction data are analyzed using a novel Vegard's law-based approach to determine the phase fractions and location of substitutional solute atoms in situ during heating from room temperature up to 1050 A degrees C. It is seen that this alloy exhibits direct nucleation of the beta (Zr) phase from martensite during tempering, and stable retention of the beta (Zr) phase to high temperatures, unlike other two-phase zirconium alloys. The transformation strains resulting from the transformation are shown to have a direct impact on the development of microstructure and crystallographic texture.