12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Alloy Development II
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
Thursday 10:50 AM
June 17, 2021
Room: Contributed III
Location: Virtual
Session Chair: John Allison, University of Michigan
Achieving Exceptionally High Strength in Mg-Al-based Magnesium Extrusions: Zhuoran Zeng1; Jian-Feng Nie2; Nick Birbilis1; 1Australian National University; 2Monash University
Exceptionally high strength Mg-Al-Zn and Mg-Al-Ca-based alloys are demonstrated herein, revealing a yield strength of more than 380 MPa. In this study, AZ31 and Mg-Al-Ca-based alloys was extruded at different temperatures to reveal an exceptionally high strength with ultrafine grains. To reveal the origin of high strength in the developed alloy, the microstructure of Mg-Al-base alloys was compared with those of Mg-1Zn alloy and pure Mg with similar grain size and textures. The solute atoms were identified to be the key to alloy strengthening (∼210 MPa). In contrast to grain boundary sliding and grain rotation that is observed submicron-grained pure Mg; the solute in submicron-grained Mg-Al-based alloys suppressed such intergranular deformation modes, with the grain boundaries in submicron-grained AZ31 providing significant strengthening (via the Hall-Petch relationship). The results herein reveal high strength Mg-alloys are readily achievable, the related concepts of which have implications for numerous Mg alloy systems.
Improving the Creep Resistance of Elektron21 by Adding AlN/Al Nanoparticles Using the High Shear Dispersion Technique: Hong Yang1; Yuanding Huang2; Karl Ulrich Kainer3; Hajo Dieringa2; 1Magnesium Innovation Centre; 2Helmholtz-Zentrum Hereon; 3Wrocław University of Science and Technology
A novel high shear dispersion technique (HSDT) was used for the first time to effectively distribute AlN/Al nanoparticles (NPs) in Elektron21 (El21) magnesium alloy. Different high shearing speeds were adopted to investigate the optimum shearing speed for optimum daegglomeration of nanoparticles and enhancing the creep resistance of AlN/Al NPs reinforced El21 alloy. The results showed that the creep resistance of El21+0.5% AlN/Al nanocomposite increased with the increasing speed of HSDT. The individual/synergistic roles of AlN and Al were also systematically identified by comparing the microstructural evolutions and creep properties of El21, El21+0.25% Al, El21+0.75% AlN and El21+1% AlN/Al. The creep results showed that the mixture additions of AlN and Al NPs give a synergistic improvement on the creep resistance of El21 alloy compared to that with single addition of Al or AlN NPs.
The Influence of Ca on the Precipitation Behavior in a Mg-rare Earth Alloy: Qianying Shi1; Bruce Williams2; Anirudh Natarajan3; Anton Van der Ven3; John Allison1; 1University of Michigan; 2CanmetMATERIALS; 3University of California, Santa Barbara
The potential effect of Ca for improving the precipitation strengthening of Mg-rare earth (RE) alloy system has not been well explored. In this study, a systematic characterization of precipitation behavior during the aging process was conducted for a Ca-containing Mg-Nd-Y alloy. In this quaternary alloy system, a very similar precipitation type and evolution sequence was observed compared to Mg-Nd-Y ternary alloy system. The clustered combination of β’’’ and β’ precipitates accounted for the aging peak at 200°C. Both TEM-EDS and APT characterization showed the Ca segregation in both β’’’ and β’ metastable strengthening phases. This indicates the positive effect of Ca to promote precipitation in Mg-RE alloys and thus enhance precipitation strengthening. The current results provide the possibility for using Ca as an alternative alloying element to reduce the level of RE elements and expand the commercial use of high strength Mg-RE alloys.
Understanding the DSA Phenomenon in Extruded Mg-Rare Earth Alloys throughout In-situ Synchrotron Diffraction and Acoustic Emission Experiments: Gerardo Garces1; Pablo Pérez1; Bryan Chávez2; Rafael Barea2; Kristian Mathis3; Kai Guan4; Daisuke Egusa4; Eiji Abe4; Paloma Adeva1; 1Cenim-CSIC; 2Universidad Nebrija; 3Charles University; 4The University of Tokyo
To analyze and explain the phenomenon, in-situ synchrotron radiation and acoustic emission experiments during compression tests have been performed in a binary extruded Mg-RE (Y, Gd and Nd) alloy with the addition of transition metals. The compression tests have been carried out at temperatures between 25-300ºC and strain rates in a range of 4×10-5 - 8×10-3 s-1, conditions in which the DSA phenomenon appears. The experiments of synchrotron radiation and acoustic emission indicate that serrations are associated with simultaneous competitive movement of diffusing solute atoms and mobile dislocations or twin boundaries taking place during plastic deformation. In addition to the pinning of mobile dislocation, the segregation of rare earth and transition metals atoms at twin boundaries results in an additional source of the serration flow.