Magnesium Technology 2021: Keynote Session
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Victoria Miller, University of Florida; Petra Maier, University of Applied Sciences Stralsund; J. Brian Jordon, Baylor University; Neale Neelameggham, IND LLC
Monday 8:30 AM
March 15, 2021
Room: RM 31
Location: TMS2021 Virtual
Session Chair: Victoria Miller, University of Florida; Petra Maier, Stralsund University of Applied Sciences
8:30 AM Keynote
Measurement of the Critical Resolved Shear Stress for Slip in Mg Alloys Using Instrumented Indentation: Warren Poole1; Shuheng Li1; Ghazal Nayyeri1; 1University of British Columbia
A critical challenge for the plasticity and fracture of magnesium and its alloys is the competition between the different deformation modes and how this changes with temperature. In the current study, the critically resolved shear stress for basal slip as a function of alloy composition and temperature has been measured using instrumented spherical indentation. Indentation offers the advantage that tests can be conducted on grains of known orientation in polycrystal samples, particularly of importance for alloys where producing single crystals is difficult. Here, it will be demonstrated that by doing tests with indenters of different radii, the critically resolved shear stress (CRSS) for can be extracted. Very good agreement was found between the CRSS values for basal slip by indentation and the literature values from single crystal tests. Finally, the contribution will also offer perspectives on quantifying additional deformation modes such as extension twining and 2nd order pyramidal slip.
9:15 AM Invited
Development of a Low-cost and Room-temperature Formable Mg Alloy Sheet with In-plane Isotropic Tensile Properties: Taiki Nakata1; Chao Xu2; Hideaki Ohashi1; Yu Yoshida3; Katsuhito Yoshida3; Shigeharu Kamado1; 1Nagaoka University of Technology; 2Harbin Institute of Technology; 3Sumitomo Electric Industries, Ltd.
Twin-roll-cast Mg-3Al-0.4Mn (mass%) alloy was continuously rolled at a warm temperature, and the room-temperature stretch formability, tensile properties, microstructures, and texture of the annealed sheets were investigated. The sheet exhibits large Index Erichsen values over 8mm due to the formation of a ring-like texture feature where the basal poles are oriented ~25° from normal direction to all direction. Fine grain structure with an average grain size of ~7um could be obtained as well, so the sheet shows moderate 0.2 % proof stress of ~160MPa and large elongation to failure over 25 % in both rolling and transverse directions. These properties could be obtained via industrially viable rolling processing which consists of homogenization, warm-temperature rolling, and annealing. This indicates that the developed alloy sheet will broaden the applications of wrought Mg alloys in automotive industries.
9:45 AM Invited
Microstructure and Fracture Toughness of an Extruded Mg-Dy-Nd-Zn-Zr Alloy Influenced by Heat Treatment: Petra Maier1; Benjamin Clausius1; Charis Joy1; Roman Menze2; Benjamin Bittner2; Norbert Hort3; 1University of Applied Sciences Stralsund; 2Meko Laser Material Processing; 3Helmholtz-Zentrum Geesthacht
The influence of microstructural changes induced by heat treatment on fracture toughness is investigated for a resorbable Mg-Dy based alloy. The initial condition is a fine-grained, hot-extruded RESOLOY (Mg-Dy-Nd-Zn-Zr) alloy consisting of lamellar LPSO structures within the matrix. Solution heat treatment causes grain growth and the formation of bulk LPSO phases. The amount of the lamellar LPSO structures reduces. Static C-Ring tests with and without Ringer solution were used to evaluate force-displacement curves and their fracture energy. The coarser-grained alloys tend to twin under plastic deformation, which is influencing the crack propagation. Bulk LPSO phases clearly hinder crack growth. The fine-grained extruded condition shows the highest force and displacement values to induce the crack, the microstructure consisting of a good balance of grain size, matrix and bulk LPSO phases and twins show highest fracture energy. Even there might be an absorption of hydrogen, the ductility under stress corrosion is high.
10:15 AM Invited
The High-solution Design of Magnesium Alloys: Yuan Yuan1; Jun Wang1; Xiongying Cheng1; Tao Chen1; Bin Jiang1; Torben Boll2; Fushen Pan1; 1Chongqing University; 2Karlsruhe Institute of Technology
The broad applications of Mg alloys are still limited by poor mechanical properties and poor corrosion resistance. Our group has found strength, ductility, as well as corrosion resistance of Mg alloys can be simultaneously enhanced by solution elements. However, most elements only show limited solubility in alpha-Mg phase. We proposed that by dissolving multi solution elements dissolved in the alpha-Mg, the enhanced entropy may bring enlarged solubility and cocktail effects to the properties of Mg alloys. Combining the First-principle calculation and CALPHAD, the excess entropies and enthalpies of multi-element dissolving into alpha-Mg were calculated. Based on the calculated promising high solution Mg alloy systems, some typical alloys were synthesized and the corresponding properties were analyzed. This alloy design strategy brings a new insight on the development of high-performance Mg-alloys.