Evaluation of air oxidation and internal stresses induced by quenching of partially Cr-coated and uncoated optimized ZIRLO part I: Materials characterization

Diana Elizabeth Burden, Timothy Michael Harrell, Cole Alexander Love-Baker, Hans William Hudyncia, David Charles Roache, Jorie L. Walters, Edward J. Lahoda, Benjamin R. Maier, Xiaodong Li

Research output: Contribution to journalArticlepeer-review

1 Citation (SciVal)

Abstract

It is critical to develop technologies that minimize risk of nuclear reactor failure. Coated claddings present an opportunity to preserve fuel rod integrity in the case of a loss of coolant accident. In this work, the material evolution of quenched Optimized ZIRLO (OPZ) rings and Cr-coated OPZ rings is studied at temperatures up to 1000 °C, until full oxidation in air is uncovered through a variety of microstructural characterization techniques, including optical analysis and X-ray diffraction. A number of microstructural reorienting and complex, multi-stage oxidation mechanisms are found to play a role in the structural and material changes. At 1000 °C, the primary failure mode of uncoated ZIRLO is breakaway oxidation; however, the introduction of a single-sided Cr coating protects ZIRLO from oxygen penetration through the exterior surface. The material is seen to undergo several microstructural reorientations from 315° to 900°C while remaining in the α-Zr phase. At 900 °C, Cr-coated OPZ begins the α to β phase transition, and the chromium diffuses into the substrate layer. When both events are present, the Cr phase change can lead to the formation of a Cr-β-Zr eutectoid, and subsequent eutectic temperature at 1332 °C. For uncoated samples, a new phenomenon of iron-rich oxide (rust) development along the ring center in air at 1000 °C is unveiled and explained as an extension of spinodal decomposition. This study is Part I of a two-part series regarding the behavior of Cr-coated and uncoated OPZ at high temperatures. Part II investigates the internal stresses and other mechanical behaviors induced by metallic restructuring and oxide development.
Original languageEnglish
Article number171658
Number of pages12
JournalJournal of Alloys and Compounds
Volume967
Early online date6 Aug 2023
DOIs
Publication statusPublished - 10 Dec 2023

Bibliographical note

This report was prepared as an account of work sponsored by an agency of the United States Government.

Data Availability Statement

Data will be made available on request.

Acknowledgements

Utilization of the FEI Quanta 650 Field Emission scanning electron microscope, Hirox RH-8800 Light Microscope, and Empyrean XRD powder diffractometer within UVa’s Nanoscale Materials Characterization Facility (NMCF) was fundamental to this work, and we acknowledge the assistance of Richard White and Dr. Diane Dickie for equipment training.

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