Magnesium Technology 2020: Fundamentals, Mechanical Behavior, Twinning, Plasticity, and Texture II
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

Thursday 2:00 PM
February 27, 2020
Room: 6C
Location: San Diego Convention Ctr

Session Chair: Tracy Berman, University of Michigan; Keerti Kappagantula, Pacific Northwest National Laboratory


2:00 PM  
Mapping Anisotropy and Triaxiality Effects in Magnesium Alloys: Padmeya Indurkar1; Shahmeer Baweja2; Robert Perez2; Amol Vuppuluri2; Shailendra Joshi2; 1National University of Singapore; 2University of Houston
    Microstructure, material properties and macroscopic stress state closely interact in determining the strength and fracture resistance of ductile metals. While a fair understanding of the microstructure-stress interaction on strength, deformation stability and damage has been achieved for common engineering alloys, the same is not true for Mg alloys. A fundamental understanding of how the net plastic anisotropy influences the macroscopic load-deformation characteristics and deformation stability will potentially aid the development of high-performance Mg alloys. A concerted multi-scale computational effort is essential in providing a deeper understanding of the deformation micromechanics of Mg alloys. In this talk, we present the relations between the loading states (principal and off-axis), microstructure (texture, plastic anisotropy, deformation mechanisms) and macroscopic responses including deformation stability through crystal plasticity (HXP) modeling and simulation. We also assess a reduced-order model of Mg plasticity against HXP observations to enable the development of guidelines for damage-tolerant materials design.

2:20 PM  
Cold Formability of Extruded Magnesium Bands: Maria Nienaber1; Jan Bohlen1; Jose Victoria-Hernández1; Sangbong Yi1; Karl Ulrich Kainer1; Dietmar Letzig1; 1Helmholtz-Zentrum Geesthacht
    In this paper, three wrought magnesium alloys with texture and microstructure modifying elements, binary M2 and the alloyed counterparts with Ca (MX21) and RE (ME21) were extruded under similar conditions. The development of microstructure and texture in extrusion differs significantly from that in magnesium rolling. Any improvement in the properties of extrusion alloys requires a better understanding of the effects of alloying elements and processing parameters and how they determine the final microstructure of flat products. Therefore, the influence on the mechanical properties and the forming behaviour (Erichsen values IE) with relation to microstructure, texture and strain rate sensitivity is presented and discussed in this paper. It can be shown that, depending on the alloying elements, there is a clear difference in texture development and strain rate sensitivity. In addition, not only the texture, but also the microstructure has a great influence on formability.

2:40 PM  
The Effect of Plastic Deformation on the Precipitation Hardening Behavior of Biodegradable Mg-Sr-Ca-Zn Based Alloys: Matteo Nicolasi1; Baoqi Guo2; Mihriban Pekguleryuz2; Mert Celikin1; Konstantinos Korgiopoulos2; 1University College Dublin; 2McGill University
    In this study the precipitation hardening behaviour of Mg-Sr-Ca-Zn based alloy system with trace additions was investigated. The effect of temperature, composition as well as initial plastic deformation on the precipitation hardening behaviour was analyzed via ageing treatments and in-depth Transmission Electron Microscopy (TEM). The as-cast microstructure of the alloys was found to be composed of interdendritic phases (Mg2(Ca, Sr) or Ca-Sr (Mg)) surrounding the α-Mg matrix. The formation of more thermally stable precipitates, lying along (0001) planes, allowed peak hardness to retain at higher isothermal treatment temperatures. On the other hand, plastically deformed samples exhibited a shift in precipitation kinetics.

3:00 PM  
Experimental Investigation of Raster Tool Path Strategy for Friction Stir Processing of Magnesium Alloy: Abhishek Kumar1; Nikhil Gotawala1; Aarush Sood1; Sushil Mishra1; Amber Shrivastava1; 1Indian Institute of Technology Bombay
    Friction stir processing is an emerging method for refining the grain structure of the metals. Single pass friction stir processing of magnesium alloys have been reported in the literature and very few works address the multi pass friction stir processing. However, most of the studies are limited to a very small region and do not show the properties of complete processed blank. In the present work, a raster tool path strategy is adopted to modify the microstructure of the as cast magnesium alloy. The tool rotation direction and tool shoulder overlap are varied to process the magnesium samples. The microstructural evolution and hardness of the processed samples is investigated. Experimental observations show that raster scan parameters significantly affect the microstructural variation within each sample and across the samples. Based on the findings, a raster tool path strategy is proposed for grain refinement without any defect in the processed region.

3:20 PM  Cancelled
Quantitative Relationship Analysis of Mechanical Properties with Microstructure and Texture Evolution in AZ Series Alloys: Joung Sik Suh1; Byeong-Chan Suh1; Jun Ho Bae1; Sang Eun Lee1; Byoung-Gi Moon1; Young Min Kim1; 1Korea Institute of Materials Science
    The present study investigated the correlation between microstructure, texture and mechanical properties in AZ series alloys. It is well-known that the yield strengths of Mg alloys are followed by the Hall-Petch relation. Nevertheless, AZ-based sheets with relatively large grain size exhibit higher yield strength than those with finer microstructure. This is mainly due to the texture strengthening. For this reason, there is an increasing need to quantify the contribution of texture and microstructure to mechanical properties in Mg alloys. A multiple regression analysis was conducted to explore the quantitative correlation of the mechanical properties with the microstructure and texture factors, such as grain size, stored energy, maximum intensity of basal poles and Schmid factor.

3:40 PM Break

4:00 PM  
On the Influence of Twinning and Detwinning on the Deformation of Mg at the Micron Scale: Mohammadhadi Maghsoudi1; Gyuseok Kim2; Markus Ziehmer1; Erica T. Lilleodden1; 1Helmholtz-Zentrum Geesthacht; 2Quattrone Nanofabrication Facility, University of Pennsylvania
    The influence of detwinning and twinning on the constitutive mechanical response of Mg was investigated via microcompression tests of single crystalline pillars of nominal [0001] and [10-10] orientations, and bicrystalline pillars containing a single {1 0 -1 2} twin boundary. The [0001] pillars exhibit the highest initial yield strength while the [10-10] and bicrystalline pillars initially yield at a significantly lower stress at which twin nucleation and growth or migration commences. Depending on the extent of straining, the [10-10] and bicrystalline pillars exhibit a secondary yield point associated with the deformation of the newly formed [0001] oriented pillar. The mechanical results point to an anisotropy in the mechanical consequence of twin motion, as characterized through the comparison of the three micropillar orientations; a twin-mediated hardening is indicated by the relative stress-strain behavior.

4:20 PM  Cancelled
An Investigation on the Microstructure and Mechanical Properties of Hot-dip-aluminized-Q235/AZ91D Bimetallic Material Produced by Solid-liquid Compound Casting: Jun Cheng1; Jian-hua Zhao1; Yao Tang1; Jingjing Shangguan1; 1Chongqing University
     The hot-dip-aluminumed-Q235/AZ91D bimetallic material was acquired by casting the melted magnesium alloy into the mould where the hot-dip-aluminumed-Q235 has been inserted to realize the light weight with optimal mechanical properties. The microstructure and mechanical properties of the aluminumed-Q235/AZ91D was investigated in this study. The result revealed that the metallurgical reaction in the interface zone which can be divided into two different layers was formed between Q235 and AZ91D. The layer close to AZ91D was composed of MgAl2O4 and Al12Mg17, and the layer adjacent to Q235 was comprise of FeAl3. What’s more, the average microhardness of the interface zone was higher than AZ91D substrate and Q235. Moreover, the average microhardness of the layer close to Q235 (469.6HV) was much higher than the layer adjacent to AZ91D (136HV) due to the existence of FeAl3 and MgAl2O4. In addition, the shear strength of Q235/AZ91D was about 8.22MPa.