Using Complexions to Fabricate Bulk Nanocrystalline Metals with Enhanced Ductility
Abstract
The technical objective of the proposed effort is to determine how complexions (i.e., structurally distinct interfacial states that are in thermodynamic equilibrium) can be used to enhance both the consolidation of bulk nanocrystalline metals and their mechanical properties. The proposed young investigator effort will focus on three fundamental questions in order to achieve the stated technical objective: Can interfacial structure be used as a new materials design variable to increase the ductility of nanocrystalline metals? How does grain boundary chemical composition influence the formation of such interfacial features, on both the nano- and mesoscale? And can grain boundary free energy be reduced using the same segregating alloying elements, so that damage-tolerant nanocrystalline metals can be created in bulk form? The proposed effort to understanding and quantify the importance of grain boundary structural states and their influence on damage nucleation will utilize a combination of high throughput processing experiments, mechanical testing, cutting-edge characterization, and new materials theory. Mechanical alloying will be used to fabricate Cu-Zr and Cu-Zr-Al alloys, with the goal of maximizing the thickness and boundary fraction of AIFs within the microstructure. Consolidation experiments are proposed to probe the competition between grain growth and densification in the presence of various complexion states. Details of the atomic grain boundary structure and chemistry will be characterized with TEM methods, while segregation patterns through the boundary network will be measured with atom probe tomography. Additionally, local mechanical properties will be measured with small-scale mechanical testing, to probe powder samples and behavior at different locations within a bulk sample. Traditional tensile tests will also be used to measure the global properties of consolidated samples.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2017
- Source ID
- W911NF1610369
Entities
People
- Timothy Rupert
Organizations
- Army Contracting Command
- United States Army
- University of California, Irvine