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Article
Thermal Stability and Mechanical Properties of Nanocrystalline Fe–Ni–Zr Alloys Prepared by Mechanical Alloying
Journal of Materials Science (2013)
  • Hasan Kotan, North Carolina State University
  • Kris A. Darling, U.S. Army Research Laboratory
  • Mostafa Saber, Portland State University
  • Ronald O. Scattergood, North Carolina State University at Raleigh
  • Carl C. Koch, North Carolina State University
Abstract
The thermal stability of nanostructured Fe100−xy Ni x Zr y alloys with Zr additions up to 4 at.% was investigated. This expands upon our previous results for Fe–Ni base alloys that were limited to 1 at.% Zr addition. Emphasis was placed on understanding the effects of composition and microstructural evolution on grain growth and mechanical properties after annealing at temperatures near and above the bcc-to-fcc transformation. Results reveal that microstructural stability can be lost due to the bcc-to-fcc transformation (occurring at 700 °C) by the sudden appearance of abnormally grown fcc grains. However, it was determined that grain growth can be suppressed kinetically at higher temperatures for high Zr content alloys due to the precipitation of intermetallic compounds. Eventually, at higher temperatures and regardless of composition, the retention of nanocrystallinity was lost, leaving behind fine micron grains filled with nanoscale intermetallic precipitates. Despite the increase in grain size, the in situ formed precipitates were found to induce an Orowan hardening effect rivaling that predicted by Hall–Petch hardening for the smallest grain sizes. The transition from grain size strengthening to precipitation strengthening is reported for these alloys. The large grain size and high precipitation hardening result in a material that exhibits high strength and significant plastic straining capacity.
Keywords
  • Nanocrystals -- Research,
  • Temperature effect,
  • Thermal stresses
Publication Date
August, 2013
DOI
10.1007/s10853-013-7652-7
Publisher Statement
Copyright (2013) SpringerLink

*At the time of publication, Mostafa Saber was affiliated with North Carolina State University.


Citation Information
Kotan, H., Darling, K. A., Saber, M., Scattergood, R. O., & Koch, C. C. (2013). Thermal stability and mechanical properties of nanocrystalline Fe–Ni–Zr alloys prepared by mechanical alloying. Journal of Materials Science, 48(24), 8402-8411.