12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Poster Session
Program Organizers: Alan Luo, Ohio State University; Mihriban Pekguleryuz, McGill University; Sean Agnew, University of Virginia; John Allison, University of Michigan; Karl Kainer; Eric Nyberg, Kaiser Aluminum Trentwood; Warren Poole, University of British Columbia; Kumar Sadayappan, CanmetMATERIALS; Bruce Williams, Canmetmaterials Natural Resources Canada; Stephen Yue, Mcgill University
Tuesday 8:00 AM
June 15, 2021
Room: Poster Session
Location: Virtual
Acoustic Emission Characteristics of Aqueous Corrosion in Mg-Zn-Y Alloys
with Long-period Stacking Ordered Phase
: Akito Furukawa1; Michiaki Yamasaki1; Daria Drozdenko2; Kristian Mathis2; Yoshihito Kawamura1; 1Kumamoto University; 2Charles University
Wrought Mg-Zn-Y alloys with long-period stacked ordered (LPSO) phase show excellent mechanical properties due to formation of multimodally heterogeneous microstructure during thermo-mechanical treatments such as extrusion and rolling. The multimodal microstructure in alpha-Mg/LPSO two-phase Mg-Zn-Y alloys consists of three regions: that is, dynamically recrystallized fine alpha-Mg grain region, hot-worked coarse alpha-Mg gain region, and LPSO phase grain region. The LPSO phase acts as alloy strengthening component. However, from viewpoint of corrosion engineering, it works as cathodic site, resulting in occurrence of Galvanic corrosion between alpha-Mg and LPSO phases. In previous studies, it has been attempted to unveil their complexed corrosion behavior using electrochemical measurements, but their corrosion processes have not been clarified yet. Therefore, in this study, corrosion processes of the alpha-Mg/LPSO two-phase Mg-Zn-Y alloy has been investigated by combination of electrochemical measurements and modern in-situ method – acoustic emission technique.
Development of Precipitation-hardenable Mg–Ag–Ca Sheet Alloys: Mingzhe Bian1; Xinsheng Huang1; Yasumasa Chino1; 1National Institute of Advanced Industrial Science and Technology
Precipitation-hardening, also known as age-hardening, is one of the most effective ways to strengthen Mg alloys. Recent studies have demonstrated that Mg–Ag–Ca system has good room temperature stretch formability, high strength and excellent flame-resistance. If precipitation-hardenability can be obtained by artificial aging, this alloy system is expected to attract more attention. In this study, attempts were made by the present authors to develop precipitation-hardenable alloys from the Mg–Ag–Ca system. A newly developed Mg–12Ag–0.1Ca (wt.%) alloy sheet shows moderate tensile yield strengths of 193 MPa, 130 MPa, 117 MPa along the rolling direction (RD), 45° and transverse direction (TD) in a solution treated condition. Subsequent artificial aging increases the tensile yield strength along the RD, 45° and TD to 236 MPa, 163 MPa and 143 MPa, respectively. This improvement in yield strength by the T6 treatment is associated with a dense distribution of Ag-enriched precipitates.
Effect of Ca Addition on Microstructure of AZ61 Magnesium Alloy during High Temperature Deformation: Kibeom Kim1; JungHoon Lee1; KwonHoo Kim1; 1Pukyong National University
Magnesium alloys have been paid attention as lightweight materials in various industrial fields. However, their use is limited by poor formability at room temperature which was caused by the limited number of slip systems. The texture control plays an important role in plastic workability of magnesium. Addition of Ca as alloying element is known to improve the general corrosion resistance and mechanical integrity of magnesium alloys in chloride environment. In order to investigate the Ca concentration on microstructure formation behaviors, Ca addition on AZ magnesium alloy were experimentally investigated by high-temperature uniaxial compression. Uniaxial compression test was conducted at 673K and 723K with a strain rate of 5.0×10-2s-1. The working softening was observed and the main component of texture and the sharpness of basal texture in two kinds of specimens varies depending on the deformation conditions.
Effect of Cation Species in the Electrolyte on the Oxidized Film on the Anodizing of Mg-Li-Al Alloys: Yuka Ichigi1; Taiki Morishige1; Toshihide Takenaka1; 1Kansai University
Mg-14mass%Li-3mass%Al (LA143) alloy has high corrosion resistance than previous Mg-Li alloys such as Mg-14mass%Li-1mass%Al (LA141). However, the corrosion properties of the alloy are not enough to apply for practical use without corrosion protection coatings. The anodization for Mg alloys is an effective technique to prevent metal surface from exposure to corrosion environment. Phosphoric acid-based solution containing metal cation are useful electrolyte to form thick oxide layer on Mg surface. In this study, the effect of cation species on the oxidized film was investigated.The film formed by each electrolytic solution was mainly composed of Mg3(PO4)2, AlPO4, MgAl2O4, and the phosphate and oxide containing each additive element were slightly present. Particularly, in the electrolyte containing Ca, the dissolution of LA143 was suppressed about twice as much as other electrolyte, and the most uniform and thick film was formed.
Effect of Pre-sintering in Silicothermic Reduction of MgO and Reduction Using Ca2SiO4 instead of CaO: Takeru Saimura1; Toshihide Takenaka1; Taiki Morishige1; 1Kansai University
Our laboratory has been researching Mg production using bittern-derived materials to develop an innovative Mg production process with lower environmental load. In previous studies, it was suggested that the contact condition between MgO, CaO and Si was very important to reduce bittern-derived material efficiently. In this study, the contact condition of MgO, CaO and Si was changed by sintering and the effect of the sintering condition on Si thermal reduction was investigated. A short-term sintering improved the reduction rate, but a longer sintering worsened the rate. Sintering seems effective in the improvement of contact condition, but cases the surface oxidation on Si. In this study, Si reduction with Ca2SiO4 instead of CaO was also attempted to reduce CaO consumption, but it was shown that MgO was lost by CaMgSiO4 formation.
Effects of MgCl2 and NaCl on Si-thermic reduction of MgO in Recycle of Mg-air Battery: Atsushi Hayashida1; Toshihide Takenaka1; Taiki Morishige1; 1Kansai-University
The effects of the chlorine content used as electrolyte should be controlled in the recycle process of Mg-air battery. The influence of MgCl2 and NaCl in Si-thermic reduction of MgO has been studied in this study. The mixture of MgO with MgCl2 or NaCl was reduced by metallic Si at 1150C° for 3h, and the reduction rate was estimated. The reduction rate without MgCl2 or NaCl addition was about 55% under our reduction condition, and 1mol% addition of MgCl2 rarely affected the reduction rate. However, the reduction rate decreased with added amount of MgCl2. and became about 15% in 10mol% addition. Even 1mol% addition of NaCl worsened the reduction rate, and the reduction rate decreased with the addition amount. It is confirmed that the chlorine content should be removed before Si-thermic reduction in the recycle of Mg-air battery.
First-principles Calculations of Phonon States in LPSO Magnesium Alloys: Daisuke Matsunaka1; 1Shinshu University
Several magnesium alloys include long period stacking ordered (LPSO) structures which consist of periodic arrangement of basal stacking faults and enrichment of solute atoms in the vicinity of the stacking faults. The solute-enriched layers give rise to a significant mass change as well as local stiffness due to the L12-type solute clusters, which affect the lattice vibration properties of the LPSO structures. Our previous study showed that for a heavy enough mass change, a phonon-mediated interaction of the solute-enriched layers is attractive and stabilizes the periodic stacking of the solute-enriched layers. In this study, we analyze phonon states of LPSO magnesium alloys, using first-principles calculations. We calculate phonon density of states and phonon dispersion based on the density functional perturbation theory.
Improvement of Corrosion Resistance by Zn Addition to Mg Alloy Containing Impurity Ni: Koki Ezumi1; Taiki Morishige1; Tetsuo Kikuchi2; Ryuichi Yoshida2; Toshihide Takenaka1; 1Kansai University; 2CHUO-KOSAN.,LTD.
There is the deleterious influence of corrosion resistance of Mg alloy by contaminant of impurity element Ni during Mg recycling. Mg2Ni precipitates trigger the galvanic corrosion between Mg matrix phase. Zn addition into Mg alloy may reduce the detrimental impact of impurities. A small amount of Ni element is dissolved into Mg-Zn intermetallic phase. Therefore, the microstructure and corrosion behavior were investigated by changing the amount of Zn in Mg alloy with a trace amount of Ni. From the results of the microstructural observation, Ni element existed in MgZn2 intermetallic phase when the Zn content exceeded 6 mass%, to change the existing state of Ni whereas Mg2Ni phase was dispersed in Mg-Zn alloy with a few percent of Zn.
Influence of Heat Treatment on the Stretch Formability of Age-hardenable Mg-Al-Ca-Mn-Zn Sheets: Marc Imiela1; Taisuke Sasaki2; Kazuhiro Hono2; David Klaumunzer1; 1Volkswagen Group Innovation; 2National Institute of Materials Science
In this work the influence of heat treatment on the stretch formability of an age-hardenable Mg-Al-Ca-Mn-Zn alloy sheet is investigated utilising Erichsen cupping tests within a temperature range from room temperature to 200°C. In contrast to traditional age-hardenable materials, such as Aluminium 6000 series sheets, the results show a lower stretch formability for the solution treated (T4) than for the peak aged (T6) condition, especially at intermediate temperatures (100-200°C). Uniaxial tensile tests reveal a significantly lower strain-rate sensitivity in the T4-condition within the same intermediate elevated temperature regime. These results have a direct implication on an envisioned industrial processing route such that forming of lightweight components should preferably be carried out on peak aged (T6) blanks.
Investigation of Microstructural Factors Affecting the Plane-strain Fracture Toughness of Mg-Zn-Y-Al Alloys Processed by Consolidation of Rapidly Solidified Ribbons: Soya Nishimoto1; Shin-ichi Inoue1; Michiaki Yamasaki1; Yoshihito Kawamura1; 1Kumamoto University
Recently, high strength and ductile nano-crystalline Mg-Zn-Y-Al alloys with LPSO phase have been developed via rapidly solidified (RS) ribbon-consolidation processing. These Mg alloys are expected to be used in aerospace industries because of their excellent mechanical properties and high corrosion resistance. However, it has been pointed out that the data on the fracture toughness of the alloys is insufficient. Therefore, in this study, we investigated fracture toughness of the alloys. The RS ribbon-consolidated Mg-Zn-Y alloys subjected to pre-extrusion heat-treatment showed higher fracture toughness than the alloys without heat-treatment. Pre-extrusion heat-treatment conditions affected the morphology of LPSO phase in the RS alloys. In the alloys without heat-treatment, plate-shaped LPSO phase precipitated in grain interior. On the other hand, in the alloys with heat-treatment, LPSO phase precipitates grew into block-shaped ones. Formation of block-shaped LPSO phase and fine a-Mg grains may improve the fracture toughness of the alloys.
On the Precipitation Evolution in a Mg-0.3Ca-0.6Zn Alloy: Zehao Li1; Taisuke Sasaki1; Du Chen2; Kang Wang2; Bi-cheng Zhou2; Kazuhiro Hono1; 1NIMS; 2University of Virginia
Age-hardenable Mg-Ca-Zn alloys are promising candidates as heat-treatable wrought alloys because of their excellent room temperature formability and high strength. This work aims at establishing a detailed precipitation sequence in the Mg-0.3Ca-0.6Zn (at.%) alloy by (S)TEM and 3DAP analysis. The monoatomic layer Guinier Preston (G.P.) zone is found to be the main strengthening phase in the peak-aged condition. The G.P. zones are thickened to the tri-atomic layer η'' and η' phases. The η'' and η' basal plates then form in pairs and get clustered upon aging followed by the transformation into η1 and η2 phases. 1000 h aging leads to the precipitation of two equilibrium phases, η, and δ. These observations have established the following precipitation sequence; S.S.S.S → solute clusters → G.P. zones→η''→η'→η1, η2 →η, δ. The structural stability of the G.P. zones and precipitates are verified by DFT calculations.
Oxide Films Formed on MoSi2 Anode in Molten MgCl2-NaCl-CaCl2 and Molten LiCl-KCl: Takamasa Miyoshi1; Taiki Morishige1; Toshihide Takenaka1; 1Kansai University
The anodic behavior of MoSi2 in molten MgCl2−NaCl−CaCl2 containing oxide ions has been investigated in this study to aim at developing an inert anode in this melt. A sharp anodic current peak appeared around 1.8V (vs. Mg / Mg2+) in a cyclic voltammogram, which suggested that MoSi2 was passivated in the melt with oxide ions. Potentio−static electrolysis was performed at various potentials nobler than the passivation potential. Oxide film was formed on MoSi2 by potentio−static electrolysis regardless of electrolysis potential. The current contributions assuming the dissolution of Mo and the formation of oxide film are estimated from the weight change and the film thickness after the potentio−static electrolysis. The formation of oxide film and its influence in molten MgCl2−NaCl−CaCl2 are compared with those in molten LiCl−KCl, and the suitable condition to form better protection film is discussed.