Magnesium Technology 2020: Poster Session
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: J. Brian Jordon, Baylor University; Victoria Miller, University of Florida; Vineet Joshi, Pacific Northwest National Laboratory; Neale Neelameggham, IND LLC
Monday 5:30 PM
February 24, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
Session Chair: Wim Sillekens, European Space Agency; Neale Neelameggham, IND LLC
F-35 (Invited): Magnesium Industries in 2020: Neale Neelameggham1; Robert E. Brown2; 1IND LLC; 2Magnesium Assistance Group Inc.
More than 85% of the world production of magnesium in the last two decades continue to be from China along with considerable consumption of magnesium in China itself. The poster will depict the status of magnesium industry worldwide. References on the global magnesium industry published during the past 5 years of note will be included. Scientific advances in the field of magnesium physical metallurgy, corrosion protection, demonstrated new production processes and application highlights will be shown.
F-36: Analysis of Deposition Path of Solid State Additive Manufacturing of AZ31 Mg Alloy: Malcolm Williams1; Thomas Robinson1; Paul Allison1; J. Brian Jordon1; 1University of Alabama
This work examines the deposition path of additive friction stir deposition (AFS-D) of AZ31 Mg Alloy. The AFS-D process was used to fabricate a 4” by 4” by 1/4” tall deposition of AZ31 Mg alloy using a differentiating raster pattern. The effect of the deposition path on material properties was examined using microstructure characterization and mechanical testing. Electron Back-Scattered Diffraction (EBSD) was utilized to evaluate the microstructure of the AFS-D specimens at high interest areas in the raster pattern compared to the microstructure of the base material. Quasi-static tests at ambient temperature were performed to evaluate the mechanical performance of the AFS-D specimens compared to that of the base material. Post-mortem analysis via scanning electron microscopy (SEM) was used to elucidate the underlying factors of mechanical response of the AFS-D specimens. Microstructure and mechanical characterization results of the AFS-D depositions of this study revealed strategies towards achieving isotropic properties.
F-39: Effect of Annealing on Microstructure and Mechanical Properties of Mg-6Al Alloy Plates Processed by Differential Speed Rolling: Honglin Zhang1; Zhigang Xu1; Sergey Yarmolenko1; Laszlo Kecskes2; Qiuming Wei3; Jag Sankar1; 1North Carolina A&T State University; 2Johns Hopkins University; 3UNCC
Room-temperature formability of wrought Mg alloys can be improved via plastic deformation. However, the inhomogeneous microstructure and residual stress of the plastically deformed Mg alloys affect subsequent processing. In this study, 6-mm thick Mg-6wt.% Al plates were obtained via DSR, with a total 50% thickness reduction, using 0.76 mm reduction per pass with a speed ratio of 2. The effects of temperature and hold time on the microstructure, texture, and mechanical properties were investigated. Compared to the as-rolled plates, annealing at 300°C for 15 min refined the grain size and increased ductility from 20.3 to 26.8% and 14.9 to 20.5% in the RD and TD directions, respectively. The ultimate strength decreased from 307 to 290 MPa in both directions; the hardness was reduced from 73 to 60 HV. The results show that a combination of DSR and annealing improves formability via a weakening of the basal texture by static recrystallization.
F-40: Effect of Gradient Nanostructure on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy under High Strain Fate: Yong Liu1; Meng Duan1; 1Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province, School of Mechatronics Engineering, Nanchang University
In order to investigate the microstructure evolution and mechanical behavior of AZ31 alloy with gradient nanostructure under high strain rate, the split Hopkinson pressure bar (SHPB) apparatus was used to testing the true stress-true strain curves under the high strain rates of 500 and 1200 s-1 of AZ31 Mg alloy with gradient nanostructure prepared by surface mechanical attrition treatment. The results showed that the AZ31 alloy with gradient nanostructure exhibits better energy absoption ability than the one with traditional homogeneous microstructure. Under high-speed deformation conditions, cracks sprout in the shear band and expand along the shear band. Gradient nanostructures can effectively inhibit the formation of shear bands and hinder the initiation and propagation of cracks. The formation of gradient nanostructures consumes small-angle grain boundaries in the microstructure and transforms them into large-angle grain boundaries. The reduction of the small angle grain boundaries makes the formation of shear bands more difficult.
Cancelled
F-41: Effect of Tension on Edge Crack of AZ31 Magnesium Alloys Sheets Prepared by On-line Heating Rolling: Jiangfeng Song1; 1Chongqing University
Compared to traditional rolling process, on-line heating rolling has been proved that it can largely enhance the formability of AZ31 sheets. Tension has been applied to the sheets in the rolling process which results in good surface quality. Edge crack is an important characteristic to be evaluated for the rolling process. The influence of tension on the edge crack of AZ31 magnesium alloys sheets rolled by on-line heating roller was investigated. AZ31 magnesium alloys sheets were subjected to single pass rolling under different reduction and different tension. The texture evolution, microstructure and fracture surface of AZ31 magnesium alloys sheets were studied. Results show that severe edge crack appears at large tension.
F-42: Effect of Zinc on Solidification and Aging Behaviour of Magnesium Alloys Containing Rare Earths: Amjad Javaid1; Frank Czerwinski1; 1Natural Resources Canada
Magnesium sheet continuously creates a great interest with potentials in a wide range of technically advanced applications. The interest was initially driven by a reduction in fuel consumption within transportation sectors and was later expanded to consumer electronic housings, components in electrification of vehicles, and aerospace applications. In a search for alloys with suitable formability, a particular attention is paid to Mg-Zn-RE (rare earth) grades. It is known that a presence of Zn in binary Mg-Zn alloys leads to enhanced strength and ductility. However, the effect of Zn on alloy formability in a presence of rare earths is less pronounced. In this report, the solidification and aging behavior of Mg-xZn-1Nd (x=1, 2, 4 wt.%) alloys are described. To analyze the phase nucleation and growth during melting and solidification the Universal Metallurgical Simulator and Analyzer (UMSA) was used. Hardness values of Mg-Zn-Nd alloys increased with increasing Zn contents both in as-cast and after heat treatments with changes being accompanied by the alloy structure refinement. The results are discussed in terms of the role Zn plays in properties of magnesium alloys containing rare earths. Increasing Zn content in the Mg-xZn-1Nd alloy sheets led to a moderate increase in ultimate tensile strength and yield stress but substantial reduction in ductility.
Cancelled
F-43: Effect of ZnO Nano-particle Addition and High Shear Process on Grain Refinement in the As-cast Magnesium: Kwangmin Choi1; Donghyun Bae1; 1Yonsei University
To enhance mechanical properties of magnesium alloys, uniform and fine grain-sized microstructure is required. Heterogeneous nucleation can be developed by high shear process in liquid metal, providing the grain size of ~300 µm. Additional grain refinement of magnesium is fabricated with an addition of ZnO nano-particles. When the particles faced with liquid metal, both Zn and O elements can be decomposed and alloyed. The oxygen atoms cannot diffuse in magnesium matrix, hence placed in the form of cluster in the magnesium matrix because of its insufficient solubility. The oxygen clusters (~10 nm in size) agglomerate while the high shear treatment to be ~50 nm. Enlarged oxygen cluster have coherent interface between particle and magnesium, so particle can act as a nucleation site for the magnesium grain. As a result, grain size of magnesium with ~ 60 µm shows higher yield strength and elongation than conventional pure magnesium.
Cancelled
F-45: Grain Refinement Technology of Mg Alloy for Road Wheel Application: Jun Ho Bae1; Young Hoon Moon1; Bong Sun You1; Ha Sik Kim1; 1Korea Institute Of Materials Science
As the lightest structure material, Mg alloys are attracting more attention in lightweight transportation and electronic parts. However, the low mechanical strength, low corrosion resistance and high manufacturing cost of Mg alloys have so far restricted its widespread industrial application. The grain refinement is an effective method to improve both strength and toughness of structure materials. It is more effective in cast Mg alloys because it can reduce the casting defects and ensure a fine and uniform microstructure. Despite many researches for several decades, most of the refining techniques are used at the laboratory scale except Zr addition, and it applicable to actual industrial fields are still limited. In this study, the developed refining technology based on carbon inoculation was applied to commercialized mass process to produce Mg road wheel product and evaluate the feasibility of Mg materials to road wheel application through analysis of microstructure and mechanical properties.
F-46: Improvement of Mechanical Properties of Mg Alloys Through Confined Rolling: Pavitra Krishnan1; Zhigang Xu2; Sergey Yarmolenko2; Jagannanthan Sankar2; Laszlo Kecskes3; Qiuming Wei1; 1University of North Carolina at Charlotte; 2North Carolina A&T State University; 3HEMI, Johns Hopkins University
Three solutionized Mg alloys namely, AZ31B, Mg-9%Al, and Mg-6%Al were hot rolled in a confined manner. The underlying microstructure of the samples after rolling were studied using optical and scanning electron microscopy (SEM). Mechanical behavior of these Mg alloys has also been investigated under quasi-static (strain rate ~10^-3 s^−1) and dynamic (Kolsky bar- strain rate ~10^3 s^−1) compressive loading conditions. Correlation and effect of the rolling parameters, initial texture, varying Al content, twinning-recrystallization transformation on the microstructure and mechanical properties of these Mg alloys have been studied to a greater extent. It has been found that texture randomization in these alloys has been key to improved mechanical properties.
F-47: Influence of Ag Additions on Formability and Strength of a Mg-Zn-Zr Alloy Subjected to Severe Plastic Deformation via Equal Channel Angular Pressing: Matthew Vaughan1; Bilal Mansoor2; Robert Barber1; Ibrahim Karaman1; Rainer Eifler3; H.J. Maier3; 1Texas A&M University; 2Texas A&M University at Qatar; 3Leibniz Universität Hannover
Silver (Ag) has been known for millennia to possess antibacterial properties, making it an ideal elemental addition for magnesium-based biomedical implants. As it is expensive, Ag is not typically utilized in large amounts in magnesium alloy design. However, trace additions of Ag have demonstrated favorable effects on strengthening via enhanced precipitation hardening in Mg-6Zn-0.5Zr (ZK60). Also, Ag has been reported to retard dynamic recrystallization in Mg-3Al-1Zn (AZ31), potentially improving alloy formability at low temperatures. Low temperature formability in-turn enables high strength in magnesium alloys, as imposed grain refinement is coupled with minimal grain growth. As severe plastic deformation techniques such as equal channel angular pressing (ECAP) can induce ultra-fine grain sizes, the present work investigates the effects of Ag addition on a Mg-4Zn-0.5Zr (ZK40) alloy’s formability during ECAP. Here, the initial findings indicate that Ag enhances formability during ECAP at low temperatures, in-turn producing high strength in the post-ECAP conditions.
Cancelled
F-48: Influence of Manganese on Deformation Behavior of Magnesium under Dynamic Loading: Ryutaro Goeda1; Masatake Yamaguchi2; Tatsuya Nakatsuji1; Naoko Ikeo1; Toshiji Mukai1; 1Kobe University; 2Japan Atomic Energy Agency
Recently, magnesium alloys are expected as lightweight structural materials, and therefore superior combination of strength and ductility is desired. It's been demonstrated that manganese solute improves room temperature ductility by facilitating grain boundary sliding (GBS), however, effects on deformation behavior under dynamic loading hasn't been fully understood yet. Therefore, strain rate dependency of flow stress and deformation mechanism of Mg-Mn was investigated by tensile tests in a wide range of strain rate. As a result, GBS induced relatively larger elongation in quasi-static conditions, while ductility was reduced due to limited accommodation of GBS in dynamic conditions. Meanwhile, in the first-principles calculations, Generalized SFE, the energy to slip an atomic layer along the slip plane, was used to estimate the deformability. Calculation results suggest manganese addition makes dislocation motion difficult. This agreed with the fact that Mg-Mn exhibited limited necking in the high strain rate regime dominated by intergranular fracture.
F-50: In-vivo Performance of Bioabsorbable BioMg 250 Mg Alloy Implants: Raymond Decker1; Jake Edick1; Steve LeBeau1; 1nanoMag LLC
BioMg 250 is a microalloyed Mg based alloy which can be strengthened by nutrient elements to reach yield strength levels of 300 MPa, with ductility of 10%, in biomedical implants. Its composition and processing have been optimized by in vitro corrosion and toxicity testing. This presentation will report on follow-on in vivo campaigns in animal models that demonstrate the bioabsorption rates, lack of toxicity (biocompatibility) and positive clinical results of BioMg 250.
F-51: Microstructure and Hardness of Porous Magnesium Processed by Powder Metallurgy Using Polystyrene as the Space Holder: Ning Zou1; Qizhen Li1; 1Washington State University
Porous magnesium (Mg) with different overall porosities (4.1±0.5%, 6.1±1.3%, 12.9±3.3%, and 19.0±6.2%) were manufactured by powder metallurgy using polystyrene (PS) as the space holder. The samples were either hot pressed or cold pressed. Two types of PS were used to study the effect of molecular weight (Mw) of polymer space holder on properties of porous Mg. Porous Mg contained small amount of MgO. The utilization of lower Mw PS as the space holder introduced less amount of MgO into porous Mg. Average pore size increased from 2.0±0.03 µm to 7.9±3.3 µm with overall porosity increasing from 4.1±0.5% to 19.0±6.2%. Hardness of porous Mg decreased with overall porosity increasing. Using PS as the space holder, porous Mg by hot pressing route exhibited higher hardness than that by cold pressing route.
F-52: Microstructure and Mechanical Properties of Mg-6Sn Alloy Processed by Differential Speed Rolling: Kamil Majchrowicz1; Zbigniew Pakieła1; Paweł Jóźwik2; Zbigniew Bojar2; 1Warsaw University of Technology, Faculty of Materials Science and Engineering; 2Military University of Technology, Faculty of Advanced Technologies and Chemistry
One of the approaches to increase formability of Mg is the use of alloying additions which decrease its stacking fault energy (SFE). Theoretical calculations showed that Sn strongly reduces the SFE of Mg and may facilitate dislocation slip in the basal and non-basal slip systems. Thus, the Mg-6Sn (%wt.) alloy has been investigated in the present study. It was processed by conventional (CR) and differential speed rolling (DSR). Since the DSR method allows to introduce intense shear deformation by controlled differentiation of rotation speeds for upper and lower rolls, it can improve formability of Mg sheets, as compared to conventionally rolled ones, by a significant grain refinement and weakening of texture intensity. The essence of the present study is a comparison of microstructure and mechanical properties of Mg-6Sn alloy processed by CR and DSR using optical and scanning electron microscopy as well as uniaxial tensile tests of miniaturized samples.
F-53: Novel Low-cost Magnesium Alloys with High Yield Strength and Plasticity: Peng Peng1; 1Chongqing University
Developing high yield strength and ductility in low-cost Mg alloys using conventional plastic forming process is a tremendous challenge. In the present study, low content of Al alloying in Mg-1Mn alloy is the aim to obtain high strength and ductility of Mg-Mnbased alloys with low cost. Experimental results revealed that phase composition of the targeted Mg-1Mn-xAl (x=0.3 wt.%, 0.5 wt.%, 1.0 wt.%) alloys were composed of α-Mn+Al8Mn5, Al8Mn5 and Al8Mn5+Al11Mn4 phase, respectively. Al-Mn particles significantly refined the dynamically recrystallized (DRXed) grains. Among them, Al8Mn5 particles exhibited the most effective grain refinement. Therefore, Mg-1Mn-0.5Al alloy containing single-phase Al8Mn5 particles possessed the finest microstructure and exhibited the best mechanical properties. The high performance of the alloy was mainly attributed to the fine DRXed grains according to the Hall-Petch effect and to the large amount of fine Al8Mn5 particles through the dispersion strengthening.
F-55: Preparing Magnesium Alloys for Electron Backscatter Diffraction: Tracy Berman1; 1University of Michigan
Electron Backscatter Diffraction (EBSD) is a powerful characterization tool that is commonly employed to study grain size, grain morphology, crystallographic texture and other important microstructure parameters. However, its relatively low atomic number and propensity to corrode can make it difficult to get high quality EBSD patterns from magnesium specimens. This work will cover some common issues encountered during sample prep and suggestions for avoiding them. Microscope and EBSD detector settings will also be covered, as well as methods for optimizing instrument time. Lastly, comments will be made on how to “clean” and present EBSD data.
F-56: Quantifying Dislocation Behavior in Mg Using a Phase Field Dislocation Dynamics Model Multiple Active Slip Planes: Claire Weaver1; Abigail Hunter2; Shuozhi Xu1; Anil Kumar2; Irene Beyerlein1; 1University of California, Santa Barbara; 2Los Alamos National Laboratory
An advanced phase field model that is capable of accounting for dislocation behavior on various slip planes in hexagonal close packed materials is used to quantify and compare equilibrium stacking fault widths, loop formation, and dislocation motion for multiple active slip modes in magnesium. Our phase field model is directly informed with density functional theory, which enables the model to consider slip-mode dependent energetics. As such, we anticipate that the intrinsic dislocation behavior, quantified using the phase field dislocation dynamics model, will be useful input informing larger-scale plasticity modeling of Mg and Mg alloys.
Cancelled
F-57: Sol-gel Based Lanthanum Phosphate Coating on Magnesium Alloys for Corrosion Resistance: Jithu Jayaraj1; Ashitha P. P2; Suja P1; A Srinivasan1; K. G. Raghu1; U. T. S Pillai1; 1CSIR-National Interdisciplinary Institute for Science and Technology; 2Indian Institute of Science Education and Research
Magnesium alloys are the lightest structural materials used in transport industries. However, their usage is limited due to poor corrosion resistance. In order to tackle this, various surface treatments and coatings are developed over the decades. Corrosion resistant coatings through sol-gel technique is an effective and simple method. In the present study, an attempt was made to achieve lanthanum phosphate based sol-gel coating to enhance the anticorrosive properties of AZ31 Mg alloys. Coating optimization was carried out at different bath pH (3, 5, 7, 8 and 9). SEM micrographs showed a dense and uniform LaPO4 coating formed on the substrate at pH 7. Elemental and phase analysis carried out using EDS, XRD and XPS confirmed the presence of LaPO4 in the coating. The corrosion performance of the coatings in 1 wt.% NaCl using electrochemical polarization and immersion test suggested that coatings obtained at pH 7 showed the highest corrosion resistance.
F-58: Study on Creep Behavior and Microstructure Evolution of T6 State Mg-15Gd Metal Mold Casting Alloy: Shuxia Ouyang1; 1Northwestern Polytechnical University
The tensile creep behavior and microstructure evolution of the T6 state Mg-15Gd (wt.%) alloy were investigated at temperatures from 235 °C to 300 °C and stresses from 50 MPa to 90 MPa. At a fixed creep temperature of 260 °C, the stress exponent n was measured to be 2.6 under 50~80 MPa and 4.8 under 80~90 MPa, respectively, suggesting that the creep deformation mechanism changed from dislocation slip to dislocation climb. Meanwhile, under a defined creep stress of 50 MPa, the activation energy Qc of the alloy was 80 kJ•mol-1 at 235 to 260 °C and 141 kJ•mol-1 at 260 to 300 °C, respectively, indicating the creep deformation mechanism changed from grain boundary sliding to dislocation climb. Furthermore, not only α(Mg) grain size but also the quantity and size of the precipitated phases increased with the increase of the creep stress, the creep temperature and the creep time.
Cancelled
F-59: The Application of Hydrogen-containing Phase Diagram Calculations on the Design of Mg-RE Hydrogen Storage Alloy: Qun Luo1; Qian Li1; Kuo-Chih Chou2; 1State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University & Materials Genome Institute, Shanghai University; 2Shanghai University
The magnesium-rare earth (RE) alloys attract much attention because of their low density, large storage capacity and good hydriding/dehydriding (H/D) kinetics. However, it is a huge task to find out the good performance among the multi-component composition space. Therefore, we focus on the composition design of Mg-RE-Ni alloys based on thermodynamic calculations including phase diagram, phase stability, phase transformation, etc. The optimized thermodynamic database of Mg-RE(RE=La, Ce, Nd, Y)-Ni-H system is used to design the Mg-based hydrogen storage alloys. The “Pressure-Composition-Temperature” curves are calculated, which precisely predicts the decomposed pressure of hydrides and maximum hydrogen storage capacity of alloys. Based on the analyzation of calculation results, two alloys (Nd4Mg80Ni8 and Mg12NiY) with excellent hydrogenation/dehydrogenation performance have been developed.
Cancelled
F-60: The Study of Galvanic Corrosion of Magnesium Alloy from the Perspective of Work Functions: Chen Tao1; Yuan Yuan1; Pan Sheng1; 1Chongqing University
The galvanic corrosion in magnesium alloys is mainly the electrochemical corrosion between Mg matrix phase with low standard electrode potential and precipitated phase with higher standard electrode potential. The literature shows that the electronegativity is related to the work function of materials. Work functions of Mg, Al, Zn, Mn, Fe, Ni and Si elements in AZ91 and the Fe-Containing and Mn-containing precipitated were calculated by density functional theory. The results show that the work function of pure elements is Ni > Si > Fe > Cu > Zn > Al > Mn > Mg. The work functions of the Al-Fe compounds is greater than the work function of the Al-Mn compounds, and the work functions of compound is related to pure element work function and crystal structure.
F-61: Thermomechanical Processing of Dilute Mg-Zn-Ca Alloys: Jenna Krynicki1; Laszlo Kecskes2; Suhas Eswarappa Prameela1; Zhigang Xu3; Timothy Weihs1; 1Johns Hopkins University; 2MATSYS, Inc.; 3North Carolina A&T State University
The use of lightweight metals in structural applications has sparked renewed interest in Mg alloys, as Mg alloys can offer high specific strengths. Under extreme conditions, spall strength and dynamic strength determine functionality. In such applications, attempts to strengthen Mg alloys with precipitates are inadequate as second phase particles act as void nucleation sites that lower spall strength. Therefore, we focused on grain refinement with a minimal number of precipitates, using a Mg-1Zn-0.2Ca (wt%) alloy as an alternative to precipitation strengthening. The alloy was processed via Equal Channel Angular Extrusion (ECAE) and confined rolling, and annealed to obtain a range of grain sizes. We then compared the as-processed and annealed microstructures, as well as the corresponding mechanical properties, measured via nanoindentation and small-scale, quasi-static tension tests. Within the context of the microstructural evolution, we will describe the ECAE processing method, testing protocols used, and enumerate the results of the effort.