12th International Conference on Magnesium Alloys and their Applications (Mg 2021): New Materials / Processes; LPSO & MFS Structures
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 10:50 AM
June 15, 2021
Room: Contributed III
Location: Virtual
Session Chair: Mert Celikin, University College Dublin; Kazuya Aizawa, Japan Atomic Energy Agency
Magnesium Hydride Slurry Aerospace Fuel with Net-zero or Net-negative Emissions: Yi Jie Wu1; Jake Scarponi1; Nolan Dexter-Brown1; Jagannath Jayachandran1; Adam Powell1; 1Worcester Polytechnic Institute
Metals such as aluminum have been used in solid fuel systems for their high energy density. Magnesium has the advantage of low toxicity – indeed, it is a nutrient. The basicity of magnesium oxide in combustion exhaust can react with atmospheric CO₂ and tie it up in precipitation. A slurry of magnesium hydride in a hydrocarbon with 1:1 Mg:C ratio has lower specific energy than jet fuel, but higher energy density which could lead to longer aircraft range. And the MgH₂ can be produced from sea water and electricity with zero emissions. Thermodynamic calculations presented here indicate that this slurry fuel may burn with higher efficiency under engine conditions, particularly at high temperature, if combustion reaches equilibrium. Experiments were carried out to compare slurry droplet combustion kinetics with hydrocarbon fuel. Atmospheric equilibrium and condensation kinetics experiments estimate potential for carbon removal from the atmosphere.
Improving Adhesive Bonding of Explosive-welded Magnesium/Aluminum Joints by Interface Design: Mingzhe Bian1; Xinsheng Huang1; Naobumi Saito1; Isao Nakatsugawa1; Yasumasa Chino1; 1National Institute of Advanced Industrial Science and Technology
Multi-material lightweight materials have recently attracted considerable attention in the automotive industry, in particular where a trade-off between reduced weight and improved performances is required. Nevertheless, joining of dissimilar lightweight magnesium (Mg) and aluminum (Al) alloys is challenging due to the marked differences in their metallurgical and physical properties and the formation of brittle intermetallic compound layers: an Al3Mg2 layer on the Al alloy side and a Mg17Al12 layer on the Mg alloy side. In this study, the feasibility of improving adhesive bonding of an explosive-welded AZX611 (Mg-6Al-1Zn-1Ca-0.3Mn in wt.%)/A6N01 (Al-0.7Mg-0.5Si-0.3Cu in wt.%) joint was explored by conventional hot-rolling process. 7 mm thick plates were rolled to 1 mm thick sheets with different rolling temperatures and thickness reduction per pass to provide an in-depth understanding of the relationship between the rolling condition, adhesive bonding and interface microstructure of the AZX611/A6N01 joint sheet.
Understanding the Poor Hardening Potential of Nanoprecipitates in Highly Alloyed Magnesium Rare Earth Alloys: Xueze Jin1; Wenchen Xu2; Debin Shan2; Bin Guo2; Bocheng Jin3; María Pérez Prado1; 1IMDEA Materials Institute; 2Harbin Institute of Technology; 3University of Southern California
This work investigates the inefficiency of a dense distribution of nanoprecipitates to strengthen a weakly textured Mg-Gd-Y-Zr alloy by micropillar compression and analytical electron microscopy. The research shows that, in grains oriented favorably for basal slip, nanoprecipitation leads to pronounced slip localization due to dislocation shearing, resulting in a modest strengthening of basal systems. Additionally, in grains with the c-axis close to the compression axis, hard basal slip dominates deformation and nanoprecipitation promotes the activation of pyramidal slip, but also with a minor effect in the strength. Finally, in grains with the c-axis almost perpendicular to the compression axis, prismatic slip dominates deformation in the solid solution state and nanoprecipitation favors twinning due to solute depletion, leading to significant softening. The modest hardening response of the weakly textured alloy is mostly attributed to the softening associated to basal slip localization due to particle shearing.
The Effects of RE-RE Elements on the Phase Stability and Mechanical Properties of LPSO Phase in Mg-TM-RE-RE Quaternary Alloys: Ken-ichi Ikeda1; Seiji Miura1; Futoshi Miyakawa1; Satoshi Takizawa1; Toshiaki Horiuchi2; Satoshi Minamoto3; Takaomi Itoi4; 1Hokkaido University; 2Hokkaido University of Science; 3National Institute for Materials Science; 4Chiba University
LPSO (Long-Period Stacking Ordered) phases in various Mg-TM-RE (TM: transition metals, RE: rare-earth elements) ternary alloys have attracted attention for high strength Mg alloys. In this study, it is attempted to confirm the existence of stable phases around the LPSO to substitution behavior of Mg-Zn-RE LPSO phase. Furthermore, the mechanical properties of each phase in Mg-Zn-RE-RE alloys are investigated by indentation tests. Quaternary alloys were prepared by melting Mg, Zn and several RE metal blocks in a high-frequency furnace under argon atmosphere, and casting in a mild steel mold. It was found that almost no Ce substitutes for Y in Mg-Zn-Y-Ce based LPSO, while Dy substitutes for Y in several Mg-Zn-Y-Dy based LPSO.
Classification of Oxide Films of Mg-X Binary Alloys and Application to LPSO-typed Multicomponent Mg Alloys: Shin-ichi Inoue1; Michiaki Yamasaki1; Yoshihito Kawamura1; 1Kumamto University
Mg alloys have high strength-to-weight ratios. However, Mg alloys easily burn and oxidize at high temperatures. To overcome the problem of flammability of Mg alloys, some reactive elements were added to Mg alloys. The reactive element oxide film formed on the Mg alloy surface may play an important role in improving incombustibility of the alloys. However, it is hard to find systematic investigation for the characterization of surface oxide film of Mg alloys in previous literatures. In this study, we have attempted to classify the oxide films of Mg-X alloys and multicomponent Mg alloys such as LPSO-typed ones. The proposed classification comprises three main types of oxides (MgO, XmOn, and XmOn/MgO) and two subgroups (thermally grown and thermal barrier) of each oxide type. The formation of thermal barrier type oxide film tends to improve non-flammability of Mg alloys regardless of sort of main oxide types.
Plastic Deformation Behavior of Lamellar-structured Mg-based Eutectic Alloys, as the "Mille-feuille Structured Material": Koji Hagihara1; Kosuke Miyoshi1; Kyohei Hayakawa1; 1Osaka University
LPSO phase is known to contribute to increase in both of strength and ductility of Mg alloys. As a deformation mode in it, kink-band formation is recently focused. However, its formation criteria have not yet been clarified. According to the study on the LPSO phase, its unique crystal structure which is constructed by the alternative stacking of soft and hard layers, called mille-feuille structure, are supposed as plausible factors to govern the formation of deformation kink bands. To confirm these assumptions, we examined the deformation behavior of several directionally solidified Mg-based two-phase eutectic alloy with lamellar microstructure as a model material, such as Mg/Mg17Al12, and confirmed the formation of kink-bands as expected. The details on this is discussed in the presentation.
Influence of Crystallographic Orientation on Corrosion Behavior of Mg-Zn-Y Alloys with Multimodal Microstructure
: Michiaki Yamasaki1; Akito Furukawa1; Yoshihito Kawamura1; Zhiming Shi2; Andrej Atrens2; 1Kumamoto University; 2The University of Queensland
Mg-Zn-Y alloys containing a long period stacking ordered (LPSO) phase have received a large amount of attention, due to its improved mechanical performance. With respect to the Mg/LPSO two-phase alloys, a heterogeneous multimodal microstructure develops during thermo-mechanical processing such as extrusion and rolling. The alpha-Mg matrix is bimodally grained; that is, it consists of fine dynamically recrystallized grains and strongly fiber-textured coarse grains. The former contributes to an improvement in ductility, while the latter contributes to mechanical strengthening of the alloy due to texture strengthening. Dispersion of LPSO phase is also effective for alloy strengthening. In other words, the extruded Mg-Zn-Y alloys involve electrochemical and geometrical heterogeneities. In this study, therefore, we have investigated influence of electrochemical and geometrical heterogeneities on corrosion resistance of extruded Mg-Zn-Y alloys with multimodal microstructure. Meticulous attention was paid to crystallographic orientation dependence of corrosion behavior of the extruded alloys.