12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Deformation & Mechanical Behaviors III
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
Friday 10:50 AM
June 18, 2021
Room: Contributed III
Location: Virtual
Session Chair: Aeriel Murphy-Leonard, Ohio State University
Influence of Extrusion Rate on Microstructure and Mechanical Properties of Magnesium Alloy AM60 and an AM60-based Metal Matrix Nanocomposite: Danai Giannopoulou1; Hajo Dieringa1; Noomane Ben Khalifa2; Jan Bohlen1; 1Helmholtz-Zentrum Hereon; 2Leuphana University Lüneburg
Metal matrix nanocomposites are attracting attention because of their great potential for improved mechanical properties or possible functionalization. These hybrid materials are often produced by casting processes, but they can also develop their property profile after hot working, e.g. by forging or extrusion. In this paper a commercial cast magnesium alloy AM60 is enriched with 1 wt.% AlN nanoparticles and extruded into round bars with varied extrusion rate. The same is carried out with the unreinforced AM60 in order to be able to determine the influences of the AlN nanoparticles in direct comparison. The influences of extrusion speed on the recrystallization behavior as well as of nanoparticles on the microstructure evolution and particle induced strengthening are discussed and assessed with respect to the resulting mechanical performance.
Comparison of Effects of Heat Treatment on Mechanical Properties and Microstructural Behavior of Extruded AZ31 and AM50 Magnesium Alloys: Irem Sapmaz1; Enes Kurtuluş1; Emrah Fahri Özdoğru1; Asım Zeybek1; 1Yesilova Holding
Magnesium alloys provide wide application areas due to their low density, high specific strength, and stiffness. However, HCP (Hexagonal Close Pack) crystal lattice structure of the magnesium can limit its formability. Thermomechanical processes like extrusion provide refined microstructure, better mechanical properties, and higher ductility than casting. Heat treatment is an effective way to enhance mechanical properties by means of precipitation hardening. In this study, tubular extruded profiles produced from AZ31 and AM50 Magnesium alloys were investigated. Profiles were artificially aged to get T5 condition. Tensile and hardness tests were carried out with the longitudinal specimens that were taken out parallel to extrusion direction. The effect of the heat treatment was presented associated with microstructural investigation via both optical microscopy and Scanning Electron Microscopy analysis of fracture surfaces. As a result, the effect of heat treatment process on the mechanical properties and microstructural behaviors of AZ31 and AM50 will be revealed.
Disproof of Pyramidal <c+a> Slip in Magnesium: Yan Huang1; 1Brunel University London
The current studies and understanding of magnesium deformation related to non-basal pyramidal <c+a> dislocations are critically discussed. The atomic configurations and crystallographic features in association with non-basal pyramidal <c+a> dislocations 1/3<11-23>{11-22} and 1/3<11-23>{10-11} have been unambiguously revealed for the first time using computer software, demonstrating that possible <c+a> dislocation core structures would involve too many atoms on multiple lattice planes and the dislocations are physically impossible. Magnesium single crystals were compressed along its hexagonal c-axis and the deformation mechanisms and fracture behaviour were fully characterized. Experimental results showed no evidence of <c+a> slip during deformation and fracture over the full range of temperatures tested from 20 deg C to 500 deg C.
Understanding Plastic Instability in Mg-Mn-based Alloys: Sangkyu Woo1; Risheng Pei2; Talal Al-Samman2; Sangbong Yi1; 1Helmholtz-Zentrum Geesthacht; 2RWTH Aachen
Plastic instability, commonly known as the Portevin–Le Chatelier (PLC) effect, manifests itself as an unstable plastic flow during tensile tests of structural materials such as steels, Al, Cu and Mg-based alloys. This phenomenon has a strong influence on diverse material properties, especially ductility, which degrades as the strain sensitivity coefficient and fracture toughness decrease, leading to unexpected vulnerabilities in the service environment. However, respective mechanisms are not yet clearly identified, especially in magnesium alloys, and this phenomenon is controlled by more complicated and various factors depending on the material. This study aims to identify the micromechanical mechanisms of PLC effect in newly developed Mg-Mn-based alloys under variation of the temperatures and strain rates. Based on the tensile tests under various conditions, the conditions in which the PLC effect clearly occurs were selected, and the correlation with microstructural factors was examined.