Abstract
Nanocrystalline oxide-dispersion strengthened ferritic alloy formation and its annealing behavior were examined through modern X-ray diffraction pattern analysis and supplemented by microhardness and microscopic measurements. The basic microstructure features, with particular emphasis on evolution of domain size distribution and defect content during mechanical and thermal treatment, were quantified via the whole powder pattern modeling approach. The microstructure of the powdered alloy, formed during mechanical alloying, evolved toward nanocrystalline state consisting of narrow dispersion of very fine crystallites with substantial dislocation density, which exhibited relatively high stability against elevated temperature. It was shown that crystallite size is seriously sustained by the grain-boundary strain, therefore coarsening of grains begins only after the density of dislocations drops below certain level. Obtaining correct results for the annealing-related data at specific temperature range required the incorporation of the “double-phase” model, indicating possible bimodal domain size distribution. The dislocation density and grain size were found not to be remarkably affected after consolidation by hot isostatic pressing.
Highlights
Nanocrystalline (NC) materials are attractive for advanced structural applications due to their high strength resulting directly from very fine microstructure, with the grain boundaries acting as pinning points retarding dislocation mobility
In the attempt to obtain a quantitative estimate of the different phenomena having impact on the grain growth during annealing, we proposed the necessary condition for the recrystallization to occur as follows: τgg > τs + τz when gg is the thermodynamic driving force for grain growth
It was found that grain growth may start when lattice strain stabilizing the nanocrystalline drops below critical value, 1 3
Summary
Nanocrystalline (NC) materials are attractive for advanced structural applications due to their high strength resulting directly from very fine microstructure, with the grain boundaries acting as pinning points retarding dislocation mobility. The dislocation density ( ) along with grain size ( D ) are undoubtedly indispensable microstructural parameters in terms of characterizing the mechanical properties of metals and alloys.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
