12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Cast Alloys 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 I
Location: Virtual
Session Chair: Alan Luo, Ohio State University
Effects of Impurity Fe on Intermetallics in AZ91: Liuqing Peng1; Jingwei Xian1; Christopher Gourlay1; 1Imperial College London
In the Mg industry, Mg-Al alloys are commonly melted/held in steel crucibles and Fe can be picked up into the melt to form Al-Mn-(Fe) intermetallic compounds (IMC) which can be potent micro-galvanic cathodes for corrosion. In this study, AZ91 was held in small Fe-0.2C crucibles at a wide temperature range of 640 – 850 °C for 4 h to obtain a different level of impurity Fe in the melt, followed by cooling at rate ~4 K/s. It is found that the increasing Fe content led to an increasing volume fraction of two Fe-rich phases: B2-Al(Fe,Mn) and Al5Fe2, and caused a change in morphology of the Al8Mn5 and Al11Mn4 particles. Direct contact between B2-Al(Fe,Mn) and Mg, and Al5Fe2 and Mg was observed at higher Fe content. The nucleation and growth of these IMCs was measured and is discussed.
Recent Studies on Grain Refinement of Magnesium Alloys: Sungsu Jung1; Yong Guk Son1; Yong Ho Park2; Young Cheol Lee1; 1KITECH; 2Pusan National University
Grain refinement of Mg alloys has been major research topic over the past decades, because it has been considered as one of the effective approaches to increase the strength and ductility, simultaneously. Among the various methods, superheating method is an effective grain refinement method of Mg-Al alloys. This process involves heating the melt to about 150℃~260℃ above the liquidus temperature, followed by a rapid cooling to the pouring temperature. With the simple control of the melt, a successful grain refinement can be achieved for grain refinement of Mg-Al alloys. However, a clear mechanism has not yet been identified yet. In this study, literatures of recent grain refinement studies were studied in detail, and experiments were performed to clarify the grain refining mechanisms of Mg–Al alloys by superheating. Grain size of Mg-Al alloys were analysed before and after superheating and intermetallic particles were thoroughly investigated using vacuum filtering technology.
Intermetallic formation during solidification of a Mg-Sn-Al-Zn-Mn alloy: Yangchao Deng1; Guang Zeng1; Christopher Gourlay2; 1Central South University; 2Department of Materials, Imperial College London
Multicomponent Mg-Sn-Al-Zn-Mn alloys involve the formation of multiple primary and eutectic intermetallics during the solidification process. Here, the formation of intermetallics in Mg-4Sn-3Al-1.5Zn-0.6Mn (TAZM4310) (wt.%) as-cast alloys was studied using thermodynamic calculations and analytical scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) detectors. The as-cast microstructure consists of Al-Mn intermetallics, α-Mg, Mg2Sn, tau-MgAlZn, and Mg17Al12 phases. Al-Mn phases were identified as Al8Mn5 and tau-AlMn with different morphologies, from both composition and crystal structure. We also found that most of the Mg-Al-Zn particles with >10 at.% Zn content were tau-MgAlZn phase in the alloy. Mg2Sn often co-existed with Mg17Al12 and tau-MgAlZn phase, forming multi-phase particles. The results have implications for understanding microstructure evolution of Mg-Sn-Al-Zn-Mn alloys during the solidification process, especially the intermetallic phases involved.
Solute and Precipitate Effects on Recrystallization Kinetics of Ce-containing Mg Alloys: Gillian Storey1; Scott Sutton2; Dan Hartman2; Amy Clarke1; Kester Clarke1; 1Center for Advanced Non-Ferrous Structural Alloys, Colorado School of Mines; 2Mag Specialties Inc.
Recrystallization kinetics of magnesium alloys can vary greatly based upon precipitate and solute content. Rare earth alloying elements, such as Ce, have been shown to improve the elevated-temperature properties of magnesium alloys. Quantifying the effects of precipitate fraction and solute content can result in fundamental understanding that will enable optimized industrial processing pathways. The baseline composition for this study is ZK60, with modified zinc and cerium additions. These alloying modifications result in variations in second phase insoluble particle type, volume fraction and distribution that have strong effects on both grain size and recrystallization. Here, we present quantitative determinations of precipitate and solute content as a function of alloying and relate these aspects to recrystallization kinetics. These results provide further insights into mechanical and microstructural characteristics, such as grain size distribution, texture, and hot working flow stress, which are affected by enhanced or retarded recrystallization kinetics.