Magnesium Technology 2023: Microstructure Evolution
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Steven Barela, Terves, Inc; Aeriel Murphy-Leonard, Ohio State University; Petra Maier, University of Applied Sciences Stralsund; Neale Neelameggham, IND LLC; Suveen Mathaudhu, Colorado School of Mines; Victoria Miller, University of Florida
Monday 2:00 PM
March 20, 2023
Room: 30C
Location: SDCC
Session Chair: Benjamin Anthony, University of Florida; Kiran Solanki, Arizona State University
2:00 PM
Effects of Ca and Zn Additions on the Static Recrystallization Kinetics and Texture Evolution in Wrought Magnesium Alloys: Tracy Berman1; John Allison1; 1University of Michigan
It has been established in the literature that additions of Ca and Zn to magnesium can yield wrought materials with a weak crystallographic texture that is desirable for formability. This study explores how Zn and Ca additions affect the static recrystallization kinetics and mechanisms in magnesium alloys compressed using a Gleeble thermomechanical processing simulator. The effect of these alloying additions on the texture evolution and grain growth kinetics during post-deformation annealing will also be discussed.
2:20 PM
A Theoretical Model for Predicting Stacking Fault Energies of Ternary Magnesium Alloys Based on High-throughput Calculation and Machine Learning: Qiwen Qiu1; Jun Song1; 1McGill University
Magnesium (Mg) and its alloys are the lightest structural metals with a high specific strength. Yet they suffer from low ductility, which limits their wide industrial applications. The stacking fault energy (SFE) is an important property for understanding the plastic behaviors of Mg. Although the SFEs of Mg alloys have been widely studied, general quantitative models to accurately predict SFEs in Mg alloys are still absent. Moreover, the SFE of common ternary alloys is rarely studied. We carry out high-throughput calculations to show the effects of single solutes and solute pairs on SFEs in ternary Mg systems. With the help of machine learning, a theoretical model for predicting SFE has been developed. The work provides some fundamental mechanistic insights for understanding dislocation behaviors in Mg alloys and useful ICME tools in developing rational alloy design recipes for Mg alloys with enhanced ductility.
2:40 PM
Precipitation Behavior in Low-alloyed Mg-Ca-Zn Alloys: Zehao Li1; Taisuke Sasaki1; Du Cheng2; Kang Wang2; Bi-cheng Zhou2; Akira Uedono3; Tadakatsu Ohkubo1; Kazuhiro Hono1; 1National Institute for Materials Science; 2University of Virginia; 3University of Tsukuba
Low-alloyed Mg-Ca-Zn alloys are promising as a base system of heat-treatable alloys because of their rapid age-hardenability. The trace addition of Zn plays a critical role in accelerating the age-hardening response and following precipitation behavior. This presentation reports on the origin of the rapid age-hardenability and precipitation sequence in a Mg-0.3Ca-0.6Zn (at.%) alloy. Positron annihilation lifetime spectroscopy indicates the absence of excess quenched-in open spaces in the as-quenched condition. Atom probe tomography (APT) results indicated the formation of a large number of Ca-Zn co-clusters in the early stage of aging is responsible for the rapid age-hardening. Microstructure analysis using aberration-corrected scanning transmission electron microscope (STEM) provided further insights into the precipitation sequence. A precise precipitation sequence is established as: S.S.S.S → G.P. zones → η'' → η' → η1 → η. The atomic structures and stability of the precipitates was verified by density functional theory calculations.
3:00 PM
Multiscale, Multimodal Characterization of Recrystallized and Non-recrystallized Grains during Recrystallization in a Hot-compressed Mg-3.2Zn-0.1Ca wt.% Alloy: Sangwon Lee1; Ashley Bucsek1; Tracy Berman1; Can Yildirim2; Carsten Detlefs2; John Allison1; 1University of Michigan; 2European Synchrotron Radiation Facility
High-strength, lightweight magnesium (Mg) alloys have substantial potential for reducing the weight of automobiles and other transportation systems and thus for improving fuel economy and reducing emissions. However, the strong crystallographic texture of rolled Mg sheet leads to poor formability and anisotropy. In specific non-rare earth Mg alloys, annealing can be used to desirably weaken the texture. Here, we present a multiscale in-situ study on the recovery and recrystallization of an 80% hot-compressed Mg-3.2Zn-0.1Ca wt.% (ZX30) alloy using high-resolution 3D X-ray diffraction microscopy (HR-3DXRD) and dark field X-ray microscopy (DFXM). We track more than 8,000 non-recrystallized and recrystallized grains during annealing. Relative changes in crystallographic orientation and volume of each recrystallized and non-recrystallized grain are measured as a function of annealing time. Finally, local strain and orientation are measured in the interior of the specific grains with a spatial resolution of 77 nm.
3:20 PM Break
3:40 PM Invited
Combined Effect of Alloying and Grain Size on the Deformation Behavior of Magnesium Alloys: Arul Kumar Mariyappan1; 1Los Alamos National Laboratory
Hexagonal-close-packed (HCP) magnesium metals are widely used in different industries due to their low-density and high specific-strength. Their applicability is restricted due to poor formability and pronounced plastic anisotropy. Commonly, the formability is improved by altering the chemistry (adding rare-earth elements like Y) or modulating the microstructure (e.g., grain-refinement). Grain-refinement alone cannot yield the desired ductility, and the scarcity of rare-earth elements also limits the alloying addition. In this work, using the crystal-plasticity framework, the combined effect of Y-content and grain size on the mechanical responses of Mg alloy is studied. The influence of alloying is represented by varying the activation stress and hardening responses of basal, prismatic, pyramidal slip, and tensile twin systems. This detailed study provides a map of strength and tension-compression asymmetry for a wide range of Y-content and grain sizes. This work provides a pathway to optimize the microstructure and chemistry to achieve excellent structural properties.
4:00 PM
Quantifying the Role of Coarse Intermetallic Particles on Twinning Behavior: Benjamin Anthony1; Victoria Miller1; 1University of Florida
Deformation twinning is a mechanism of critical interest in magnesium alloys and other HCP metals, both due to its ability to accommodate strain and its tendency to contribute to failure by providing a preferential crack pathway along twin boundaries. This deleterious behavior is worsened by instances of twin transmission, where a twin impinging on a grain boundary nucleates an adjacent, connected twin in the neighboring grain due to intense local stresses. Many commercial Mg alloys feature coarse grain boundary intermetallic particles in their as-produced state which potentially impede or exacerbate the localized stresses that play a role in both twin transmission and twinning behavior. Combined EDS-EBSD is used to analyze grain boundary particles, deformation twins, and transmission events to determine how particle morphology, position, and grain orientation modify twinning behavior and transmission likelihood, and how these findings compare to computational results from Crystal Plasticity – Fast Fourier Transform modeling.
4:20 PM
Optimization of the Microstructure and Performance of Aluminum Alloy Cold Spray Coatings on Magnesium Alloys: Sridhar Niverty1; Rajib Kalsar1; Anthony Naccarelli2; Timothy Eden2; Glenn Grant1; Vineet Joshi1; 1Pacific Northwest National Laboratory; 2Pennsylvania State University
The widespread implementation of Magnesium alloys for the automotive industry warrants an improvement in their corrosion performance and their ability to withstand dissimilar material contact under corrosive environments. Solid-phase coating methods offer opportunities to precisely tune the coating microstructure, thickness, and coating-substrate interface. We report on the optimization and characterization of cold spray deposited AA6061 aluminum alloy coatings on Magnesium alloy coupons and automotive components. Coatings with low porosity, high thickness, hardness, and excellent corrosion properties were achieved using a bond coating composed of pre-treated CP-Al powders. The dynamic nature of the cold spray process enabled the formation of a metallurgical bond at the coating-substrate interface leading to high adhesion strengths. Furthermore, the ability of cold spray coatings to repair manufacturing defects was explored, and the microstructural mechanism for the same was investigated.