Magnesium Technology 2017: Keynote Session
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Kiran Solanki, Arizona State University; Dmytro Orlov, Lund University; Alok Singh, National Institute for Materials Science; Neale Neelameggham, Ind LLC

Monday 8:30 AM
February 27, 2017
Room: 5A
Location: San Diego Convention Ctr

Session Chair: Kiran Solanki, Arizona State University; Dmytro Orlov, Lund University

8:30 AM Introductory Comments

8:45 AM  Keynote
Multi-scale Investigation on Yield "Symmetry" and Reduced Strength Differential in an Mg-Y Alloy: Dalong Zhang1; Lin Jiang2; Xin Wang3; M. Kumar4; Irene Beyerlein4; Julie Schoenung3; Mo Li5; Subhash Mahajan2; Enrique Lavernia3; 1University of California Irvine; 2University of California, Davis; 3University of California, Irvine; 4Los Alamos National Laboratory; 5Georgia Institute of Technology
    Mg and its alloys are promising candidates for light-weighted structural applications, e.g., aircraft, automobile, electronic, etc. However, the inherent hexagonal close packed crystal structure makes the deformation of Mg anisotropic, namely deformation only occur by dislocation slip in the close-packed (0001) plane (i.e., basal plane), or by deformation twinning in {1012} planes. Consequently, polycrystalline Mg alloys undergone thermos-mechanical processing usually contain strong texture, i.e., preferred crystallographic orientation in grains. The texture in turn leads to anisotropic deformation in wrought Mg alloys. For example, in extruded Mg alloys, the compressive yield strength is usually much lower than the tensile yield strength (so-called yield asymmetry and strength differential). It is the anisotropy that hinders the broader application of Mg alloys. Recent modeling study on Mg predicts that certain alloying elements, particularly rare-earth elements (e.g., Y, Ce, Nd, Gd, etc), could alter the active deformation modes, and promote more homogeneous deformation and overall mechanical properties in Mg. Therefore, this work aims to investigate experimentally the effects of alloying element Y in reducing the intrinsic and extrinsic anisotropy, modifying texture, and enhancing the overall strength and ductility for Mg. Fine-grained Mg 2.5 at.% Y alloy (FG Mg-2.5Y) was prepared by powder metallurgy method, including gas atomization for producing Mg-2.5Y powder, degassing and hot isostatic pressing (HIP), and hot extrusion. Both the as-HIPed and the as-extruded materials were characterized by electron back-scattered diffraction (EBSD), transmission electron microscopy (TEM), and/or atom probe tomography (APT). Tension and compression tests were carried out along the extrusion direction (ED) for FG Mg-2.5Y. Unlike common Mg alloys exhibiting yield asymmetry, the FG Mg-2.5Y exhibits virtual yield “symmetry” and significantly reduced strength differential. Namely the deformation is more isotropic. In addition to post-mortem TEM characterization for deformed FG Mg-2.5Y, in-situ TEM was also performed at the National Center for Electron Microscopy (NCEM), in an effort to understand the fundamental deformation mechanisms in FG Mg-Y that lead to reduced anisotropy. In-situ TEM for single-crystal Mg-Y nano-pillars reveals that deformation twinning is replaced by dislocation slip in non-basal planes (i.e., prismatic planes), which diametrically differs from any other Mg alloys.

9:25 AM  Keynote
Targeting High Impact R&D for Automotive Magnesium Alloys: William Joost1; 1U.S. Department of Energy
    Application of magnesium alloys in vehicles can reduce weight, increase fuel efficiency, and improve vehicle performance. So why aren’t today’s cars and trucks made of magnesium? A long list of technical and commercial challenges introduces barriers to use, and properly addressing all barriers for all components throughout a vehicle would require enormous resources (and may not be ideal anyway). However, there are key components and structures where magnesium provides the greatest potential benefits. Targeting the critical issues of cost, corrosion, and formability for the most promising vehicle applications offers a route towards efficient use of R&D resources and greater likelihood of commercial success. Following a discussion on the state of the art, these applications and challenges are summarized and a discussion of new opportunities is presented.

10:05 AM Break

10:30 AM  Keynote
Magnesium Development as a Lightweight Material - In Competition with Other Structural Materials: Alan Luo1; 1The Ohio State University
    Magnesium is emerging as a lightweight material for mass reduction and structural efficiency in the automotive, aerospace and consumer industries, but is currently only a niche material competing with other structural materials such as advanced high-strength steels, aluminum and carbon-fiber-reinforced polymers. This talk will discuss what the magnesium community can learn from our competition, what critical technologies needed for magnesium to become a main stream material for automotive lightweighting. This talk will also present successful examples of multi-material lightweighting in the automotive industry, and highlight the role of magnesium in providing lightweight solutions when competing with other structural materials. Opportunities and challenges for automotive applications of magnesium will be discussed.

11:10 AM  Keynote
The Continued Quest for Low-temperature Formability in Mg Alloys: Historical Developments and Future Opportunities: Suveen Mathaudhu1; 1University of California, Riverside
    It is well-known that opportunities for the application of wrought magnesium alloys have been limited by the limited low-temperature formability. The roots of this problem lie in the limited number of active slip mechanisms which results in strong deformation anisotropy, and thus brittle behavior. In this talk, a timeline of historical developments in magnesium alloy formability enhancement will be presented. Then, emerging solutions will be considered with an eye towards alloy/precipitate control mechanisms for activation of non-basal slip modes, and reduce/randomized texture. The scientific opportunities and challenges for each mechanism will be deliberated, and future research and development opportunities will be considered.