Background Precipitate strengthened metals are ubiquitous in a variety of structural applications. A great deal of work has been done to try to understanding the behavior of these materials. To date, however, the approach has been to conduct a significant number of mechanical tests on materials with varying alloying composition, heat treatments, etc. The tradition approach has provided a somewhat myopic understanding of material behavior because the experimental and modeling behavior is restricted to a specific alloy with a given composition and heat treatment. Furthermore, bulk mechanical tests give us an average constitutive behavior of the material which is a function of the complex microstructure of the alloy. The deformation behavior of precipitate strengthened alloys, such as Al-Cu alloys, is controlled by dislocation-particle interactions. If the precipitates are fine and coherent, precipitate shearing takes place. In the overaged condition, the particles are larger and incoherent with the matrix and Orowan by-pass takes place. Analytical solutions exist that correlate the stress to bypass the dislocation, for example, with the spacing between particles,(Orowan, 1947). Experimental verification of these models is very difficult because the models assume very idealistic conditions, i.e., no variability between size and spacing of particles, a single slip plane, etc. Advances in experimental characterization and simulation tools enable us to obtain a bottomup understanding of material behavior. In this proposal, we propose to obtain a fundamental understanding of the precise mechanisms for complex dislocation-precipitate interactions. Using a combination of experiments and simulations, we will be able to determine the optimum microstructure necessary to obtain the desired mechanical properties. The proposed work will serve as a potentially transformative effort in designing microstructures of metallic alloy.
|Effective start/end date||8/8/14 → 8/10/17|
- DOD-ARMY-ARL: Army Research Office (ARO): $359,548.00