High Temperature Behavior of Zirconium Alloys

Document Type

Student Presentation

Presentation Date

April 2016

Faculty Sponsor

Darryl Butt


Zirconium alloys are routinely used as materials in the nuclear industry due to the low absorption of thermal neutrons, favorable mechanical properties, and reasonably good corrosion resistance in normal water reactor operating conditions. However, under transient conditions, zirconium alloys may be exposed to oxidizing atmospheres and temperatures up to 1000°C. The effect of transient conditions on zirconium alloys is not well understood. Transients can result in changes in volume, grain morphology, and composition, which may impact the mechanical integrity of the material. Therefore, the focus of this study is to investigate the behavior of the Zircaloy-3 (Zr-3) and Zircaloy-4 (Zr-4) alloys under these conditions. To simulate thermal transients, the alloys were annealed and quenched in inert atmospheres. Microstructure and chemical compositions were compared before and after thermal treatments using a scanning electron microscope, energy dispersive spectroscopy, and optical microscopy. Zirconium undergoes a structural phase transformation from HCP → BCC at 863°C, which results in a volume contraction. The elements introduced during the zirconium alloying process changes the phase transformation temperature. Differential scanning calorimetry was used to measure changes in the phase transformation temperature. The results of this investigation are reported here.

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