Magnesium Technology 2021: Alloying & Processing / Primary Production
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

Wednesday 2:00 PM
March 17, 2021
Room: RM 31
Location: TMS2021 Virtual

Session Chair: Vineet Joshi, Pacific Northwest National Laboratory; Joshua Caris, Terves, LLC


2:00 PM  
Absorbable Wire Radiopacity: Influence of Composition and Size on X-ray Visibility: Adam Griebel1; Aubrey Ehle2; Jeremy Schaffer1; 1Fort Wayne Metals; 2Indiana University School of Medicine
    Imaging systems employing X-rays (such a 2D projectional radiography, computed tomography, and fluoroscopy) are widely used in medicine to aid in surgical planning, intervention, and follow-up. Visualization of medical devices using these techniques relies on differences in x-ray absorption between the medical device and the surrounding tissue. The amount of absorption of a given device is largely a function of its cross-sectional dimensions and density. Consequently, imaging of relatively small devices, like stents, made of a low-density material, like magnesium, can be very challenging. The aim of this study is to determine the influence of magnesium alloy composition on radiopacity, and at what diameters wires are no longer visible. This is accomplished by producing wires from four different magnesium alloys, in sizes ranging from 0.2 to 1.0 mm diameter, and imaging on a clinical x-ray system.

2:20 PM  
Magnesium and Magnesium Alloy Powder Processing Towards the Development of Near Shape Structural Materials: Steven Johnson1; Dylan Goncalves1; 1Central Connecticut State University
    Near shape forming of magnesium (Mg) alloys offers a significant opportunity for structural material light weighting. In this work, conventional press and sinter near shape processing has been applied to commercial AZ91D and pure Mg powders. Results indicate these powders are reasonably compressible achieving green densities of 88 to 98% Th with limited cracking. Sintering of these compacted powders is challenging and requires both solid state and transient liquid phase mass transport apparently due to the inherent powder particle surface oxide layer. Resultant press and sintered materials are characterized for density, porosity distribution, hardness, microstructure, and phase development. Throughout this effort, specific attention is paid to the affect oxygen, as an adsorbed contaminant and a surface thin film, presents as an impediment to solid and transient liquid state densification. Results of this work are intended to advance near shape processing of Mg alloy and Mg powders for potential structural applications.

2:40 PM  
Effect of Processing Parameters on the Microstructure and Mechanical Behavior of Additively Manufactured WE43 Mg Alloy: Leila Sorkhi1; Joshua Hammell1; Grant Crawford1; 1South Dakota School of Mines & Tecchnogy
    Magnesium alloys have been used as biodegradable load-bearing implants owing to their compatibility, comparable mechanical properties to natural bone, and unique ability to naturally degrade in the physiological environment. Recently, additive manufacturing (AM) of Mg has gained significant interest due to the potential to develop compositionally gradient biodegradable implants and complex implant designs for improved biological function. In this work, the effect of AM processing parameters (e.g. laser power, interlayer interval time, etc.) on microstructure and mechanical properties of Mg parts fabricated using laser powder directed energy deposition (LPDED) is studied. Microstructure was characterized using optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and electron backscatter diffraction. Mechanical behavior of the samples was investigated using microhardness and uniaxial tensile testing. Moreover, additively manufactured samples were post-processed using (HIP and heat treatment) and the effect of post-processing on microstructure and mechanical behavior of the additively manufactured samples was also evaluated.

3:00 PM  
Effects of Hot Isostatic Pressing on the Microstructure and Properties of Mg-Gd-Y-Zn Alloys: Janet Meier1; Joshua Caris2; Alan Luo1; 1Ohio State University; 2Terves LLC
    Hot isostatic pressing (HIP) treatment after annealing has been posited to simultaneously reduce casting porosity and increase mechanical properties of Mg-Gd-Y-Zn alloys with high long-period stacking order (LPSO) 14H phase fractions. Plate and cylinder samples of three different compositions were cut from permanent mold castings. The alloy samples were solution treated for 25 hours at 500°C and processed with the following HIP conditions: 485-490°C, 100-200 MPa, for 2 hours. Under accelerated corrosion conditions (submersion in 3%KCl at a temperature of 90oC), the corrosion rate was observed to increase after HIP. The mechanical properties generally increased with HIP. As there was little observed change to sample density, the authors attribute the change in corrosion rate and mechanical properties to microstructural changes with the HIP thermal cycle. CALPHAD analysis of the three compositions as well as scanning electron microscopy (SEM) microstructural observations are provided.

3:20 PM  
Low-cost Magnesium Primary Production Using Gravity-driven Multiple Effect Thermal System (G-METS) Distillation: Madison Rutherford1; Armaghan Ehsani Telgerafchi1; Gabriel Espinosa1; Adam Powell1; David Dussault2; 1Worcester Polytechnic Institute; 2Elemental Beverage
    Vapor compression distillation (VCD) in a gravity-driven multiple-effect thermal system (G-METS) distiller can reduce the energy use and cost of magnesium distillation refining by up to 90% vs. today's batch distillation processes. This could potentially provide a key unit operation for efficient primary production of magnesium from MgO, by molten salt electrolysis using a reactive cathode e.g. liquid tin followed by VCD separation. This work presents a techno-economic model of cost, energy consumption, and emissions associated with magnesium primary production by this reactive cathode molten salt electrolysis process with a G-METS distiller. The model includes a mass balance with 17 elements, electrolysis process energy balance with carbon or solid oxide membrane anodes, and detailed operating and capital cost estimates. Based on the properties of magnesium and expected operating conditions, the cost of magnesium production using this process could be comparable to or lower than that of aluminum production.

3:40 PM  
Efficient Low-cost Gravity-driven Multiple Effect Thermal System (G-METS) Distillation of Magnesium: Armaghan Telgerafchi1; Gabriel Espinosa1; Madison Rutherford1; Adam Powell1; David Dussault2; 1Worcester Polytechnic Institute; 2Elemental Beverage Company
    Vapor compression distillation (VCD) can reduce the energy use and cost of magnesium distillation refining by up to 90% vs. today's batch distillation processes. This work describes a new continuous gravity-driven multiple effect thermal system (G-METS) process for magnesium VCD with just one internal moving part. The distiller will likely use less than 1 kWh/kg magnesium product, and high throughput of the continuous process can lower capital cost considerably. A detailed thermal model of the system presented here describes multicomponent evaporation, and batch distiller experiments validate key components of the model. There are multiple alloy distillation challenges with potential solutions described here, including liquid diffusion resistance, aerosol carry-over, and removal of volatile elements such as zinc. This efficient low-cost process could play a key role in multiple new flow sheets, from magnesium alloy recycling to rare earth magnet recycling to primary magnesium production.

4:00 PM  
Industrial Practice of Extracting Magnesium from Serpentine: Huimin Lu1; Neale Neelameggham2; 1Beijing Ofikintai Technology Co., Ltd.; 2IND LLC
    There are 140 million tons of nickel-containing serpentine mines in Tuquan County, Inner Mongolia, China. There is no industrial practice in the world to extract magnesium metal from magnesium silicate minerals. Laboratory research shows that it is difficult to extract magnesium metal from serpentine. Based on laboratory research, an industrial demonstration production line with an annual processing capacity of 21,000 tons of ore has been constructed. Especially the continuous vacuum metal magnesium reduction furnace developed by ourselves is stable and reliable, which proves its feasibility. From ore crushing, grinding, ball pressing, reduction, to metal magnesium refining and casting ingots, the entire production line is fully continuous and automated. The production process has no carbon dioxide emission, clean production, high production efficiency and low cost, which lays the foundation for large-scale industrialization of extracting magnesium metal from serpentine.