High temperature, low neutron cross-section high-entropy alloys in the Nb-Ti-V-Zr system

Research output: Contribution to journalArticlepeer-review

Authors

  • D. J. M. King
  • S. T. Y. Cheung
  • S. A. Humphry-Baker
  • C. Parkin
  • A. Couet
  • M. B. Cortie
  • G. R. Lumpkin
  • S. C. Middleburgh

Colleges, School and Institutes

External organisations

  • Imperial College London
  • University of Wisconsin, Madison, WI, USA
  • University of Technology Sydney
  • Australian Nuclear Science and Technology Organisation
  • Bangor University

Abstract

High-entropy alloys (HEAs) with high melting points and low thermal neutron cross-section are promising new cladding materials for generation III+ and IV power reactors. In this study a recently developed high throughput computational screening tool Alloy Search and Predict (ASAP) has been used to identify the most likely candidate single-phase HEAs with low thermal neutron cross-section, from over a million four-element equimolar combinations. The selected NbTiVZr HEA was further studied by density functional theory (DFT) for moduli and lattice parameter, and by CALPHAD to predict phase formation with temperature. HEAs of NbTiVZrx (x = 0.5, 1, 2) were produced experimentally, with Zr varied as the dominant cross-section modifier. Contrary to previous experimental work, these HEAs were demonstrated to constitute a single-phase HEA system; a result obtained using a faster cooling rate following annealing at 1200°C. However, the beta (BCC) matrix decomposed following aging at 700°C, into a combination of nano-scale beta, alpha (HCP) and C15 Laves phases.

Details

Original languageEnglish
Pages (from-to)435-446
Number of pages12
JournalActa Materialia
Volume166
Early online date8 Jan 2019
Publication statusPublished - Mar 2019

Keywords

  • High-entropy alloys, Zirconium alloys, Modeling, Microstructure, Electron microscopy