Thermodynamics of strength and ductility in refractory compositionally-complex alloys
Abstract
The proposed research will study the relationship between intrinsic room temperature ductility and fundamental thermodynamic quantities, specifically the relative phase stability between the body-centered cubic (BCC) and hexagonal close-packed (HCP) phases, differenceG, in refractory-based compositionally-complex alloys (R-CCAs). R-CCAs exhibit exceptional strength at room temperature and elevated temperatures, but suffer from brittle behavior at room temperature, a consequence of the low ductile-to-brittle transition temperature suffered by BCC alloys. In general, tensile ductility in R-CCAs is observed to increase as differenceG decreases, and the mechanism changes from dislocation slip to TRIP behavior when differenceG becomes negative. These observations lead to the hypothesis- Ductility in R-CCAs, whether mediated by dislocation slip or TRIP mechanisms, is related to the relative stability between the BCC and HCP phases. The proposed research combines nanoindentation with energy dispersive X-ray spectroscopy and electron backscatter diffraction to provide high-throughput measurements of mechanical properties across a large region of R-CCA composition space. Simultaneously, in situ neutron and synchrotron X-ray diffraction, along with transmission electron microscopy, will be employed to quantify mechanical properties, identify deformation mechanisms, and study dislocation dynamics in bulk alloys. The results of the proposed work will elucidate the link between chemistry and mechanical behavior in R-CCAs, and provide a pathway for the design and development of new materials with properties tailored for specific Defense applications, improving future warfighter lethality and survivability; while simultaneously opening the door for potential use of R-CCAs in civilian application such as energy production.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 06, 2024
- Source ID
- FA95502310503
Entities
People
- Eric A. Lass
Organizations
- Air Force Office of Scientific Research
- Office of the Secretary of Defense
- University of Tennessee