Hexagonal close packed (HCP) metals such as magnesium and titanium have the potential to provide unprecedented combinations of mechanical properties. Successful incorporation of HCP metals into engineering designs is, however, hindered by their limited plasticity. Recent research results have introduced the exciting potential of an approach termed "twin mesh engineering". which can be applied to induce simultaneous strengthening and toughening in HCP metals. This Designing Materials to Revolutionize and Engineer our Future (DMREF) award supports fundamental research to formulate the scientific framework required to design twin meshes. The integrated experimental and modeling research activities will seek to discover if alloying can be used to create the right twin mesh for high strength, high toughness HCP alloys. The resulting materials will have applications in energy efficient manufacturing where materials with attributes such as high strength, low density, room-temperature formability and cost competitiveness are required. A diverse group of student researchers will participate in the research program at both the graduate and undergraduate levels.
This award will support a research collaboration between the Universities of California at Santa Barbara, Irvine and Davis to explore interrelationships between slip and twinning in HCP metals, such as magnesium and titanium. As fine slip tends to accentuate twinning in FCC metals, one of the goals of this research will be to evaluate the influence of alloying elements on slip patterns, both experimentally and computationally using first principles. After discerning compositions that twin readily, textures that enable the formation of 3-D twin meshes in polycrystalline samples will be assessed computationally. Since slip and twinning occur concomitantly, twin meshes will block both slip and twins, leading to strengthening and toughness. The knowledge generated from this research will be used to create a multiscale tool kit, called the twin-mesh module (TMM), which when fully operational will coordinate calculations pertaining slip-twin and twin-twin interactions, processing, twin-mesh microstructure evolution, and properties. Experimentally validated TMM will accelerate materials discovery and design of HCP alloys by providing guidance on processing pathways to create 3-D twin meshes that are consistent with industrial practices. This advancement along the Materials Development Continuum will lead to expanded use of low-density, high strength, high toughness alloys, reducing weight and fuel consumption.
