Gas nitriding behavior of refractory metals and implications for multi-principal element alloy design
Journal Article
·
· Journal of Alloys and Compounds
- Univ. of Minnesota, Minneapolis, MN (United States); OSTI
- Univ. of Minnesota, Minneapolis, MN (United States)
Multi-principal element alloys (MPEAs) comprise a large, flexible compositional space that enables tuning of their chemistry, structure, and properties. Here, to facilitate the development of nitriding-based surface-enhancement strategies that harness a broad compositional space, this study examined the gas nitriding behavior of Hf, Mo, Nb, Ta, Ti, and Zr as a function of time, temperature (750 and 1000 °C), and nitriding potential (i.e. ammonia-to-hydrogen ratio). These metals were selected because they have a strong driving force to form nitrides, and appear in many promising refractory MPEA compositions. The nitriding temperatures were selected based on the phase transformation temperature of Ti and Zr, and the nitriding potentials were chosen such that all elements are expected to form nitrides. Mass gain measurements indicate that all six elements follow parabolic kinetics. The microstructure observations and quantitative microchemical analysis show formation of dense and well-adhered compound layers for Mo, Nb, and Ta. Thick diffusion zones appear in Hf, Ta, Ti, and Zr, and diffusion coefficients were fit to the composition profiles. Partial delamination of the compound layer occurred for Ti and Zr. Peak hardness values above 30 GPa are obtained in the dense compound layers, and the solute hardening of the underlying alloy is correlated with the nitrogen content. The results provide insight into the dynamics of nitride compound formation relative to interstitial dissolution of nitrogen, and are discussed in the context of MPEA composition and processing design.
- Research Organization:
- Krell Institute, Ames, IA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- NA0003960
- OSTI ID:
- 2417933
- Journal Information:
- Journal of Alloys and Compounds, Journal Name: Journal of Alloys and Compounds Journal Issue: C Vol. 947; ISSN 0925-8388
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Computational discovery of ultra-strong, stable, and lightweight refractory multi-principal element alloys. Part I: design principles and rapid down-selection
NOTES ON THE FORGING OF REFRACTORY METALS
Journal Article
·
Sun May 28 20:00:00 EDT 2023
· npj Computational Materials
·
OSTI ID:1975566
NOTES ON THE FORGING OF REFRACTORY METALS
Technical Report
·
Wed Dec 20 23:00:00 EST 1961
·
OSTI ID:4798331