Collaborative Research: A Theoretical and Experimental Study of Mechanical Properties in Ultrafine-Grained Alloys

University Of California-Riverside, Riverside CA

Investigators

Abstract

Magnesium alloys are the lightest of all structural metallic materials, and are becoming of increasing interest due to their combination of low-density, moderate strength and stiffness, availability and recyclability. In particular, these properties are of direct relevance to the automobile, rail and aerospace industries that seek to replace heavier components with lighter ones, and thus minimize fuel usage. Despite the increased interest, magnesium alloys suffer from not being strong enough, and more so, that components have to be heated and shaped at very high temperatures, which is economically prohibitive for transportation manufacturers. This award supports fundamental research to acquire knowledge that will enable synergistic increases in strength and lowering of the processing temperature to ambient temperatures, thereby solving two important barriers to usage at one time. This research will intersect at the boundaries of materials science, mechanics and manufacturing in a highly relevant way. It will attract, educate and enable students from underrepresented groups to gain the knowledge and confidence to directly address the rigorous, evolving needs in U.S. industry and government for lightweight materials in energy efficient transportation. Cast magnesium alloys have suffered from poor ambient temperature plasticity due to the lack of necessary active slip systems. This problem is compounded in wrought processed alloys wherein highly anisotropic textures limit uniform material flow. On the other hand, nanocrystalline materials with grain sizes below 100nm have exceptional and desirable properties when compared to their course-grained counterparts, including concurrent increases in strength and ductility. Motivated by this, the goals of this project are 1) to uncover the underpinning mechanisms for ambient temperature plasticity in bulk, fully dense, nano-grained magnesium alloys using novel processing approaches and microstructure-based modeling; and 2) to exploit the subsequent knowledge to predictably design and fabricate low-temperature formable magnesium alloys. In terms of broader scientific ramifications, the development of a tractable and systematic experimental and modeling framework will represent a major advance over current semi-empirical methods for designing nano-grained alloys with tailored microstructures.