Ascertaining the Thermo-Mechanical Mechanisms of Solute-Stabilized Nanocrystalline Alloys
Abstract
There is considerable interest in the use of solutes to partition to grain boundaries and provide either thermodynamic and/or kinetic based stabilization against grain growth in nanocrystalline alloys. With these smaller grains, significant increases in strength are achieved. However, in large part, most of the experimental and modeling work has addressed this nanocrystalline stability only as a function of temperature. Yet, pressure (stress) is also a thermodynamic state variable that can alter stability criteria. For nanocrystalline stability to come into fruition, the ability to elucidate stability criteria under both temperature and load is essential. This program aims at understanding how nanocrystalline stability changes under thermo-mechanical loading through an integrated experimental (Thompson) and modeling (Tucker) effort. The objective of this study is then to elucidate how the thermo-mechanical (TM) load alters the stability criteria and deformation mechanisms in nanocrystalline (NC) stabilized alloys. The specific objectives are the following: a) Development of pure and alloyed atomistic NC structures of different grain sizes the match realistic microstructures. This is complemented by the experimental fabrication of mono-disperse nanocrystalline grains of various sizes and solute contents. b) The study of grain boundary specific solute segregation and the stabilization trends by employing atomistic simulations and experimental testing/characterization of the grain boundaries in polycrystalline microstructures. c) Deciphering the complex competition of nanoscale deformation modes in NC alloys and studying how the governing deformation mechanisms are altered by the solute-stabilization at different TM loads via simulations matched to experimental mechanical tests.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 06, 2018
- Source ID
- W911NF1710528
Entities
People
- Gregory B. Thompson
Organizations
- Army Contracting Command
- United States Army
- University of Alabama