Mechanical properties of nanoglasses and nanolaminate composites combining metallic glasses and nanoglasses
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Abstract:
Nanoglasses (NG), metallic glasses (MG) with a nanoscale grain structure, have the potential to considerably increase the ductility of traditional MG while preserving their outstanding mechanical properties. I will discuss results of molecular dynamics simulations of CuZr NG with grain sizes between 3 to 20 nm. Results indicate a transition from brittleness to ductility to nearly superplastic flow for decreasing grain size. Giving the outstanding ductility of NGs with nanometer grain sizes we consider their use in as promising material for the design of MG composites. The results of tensile loading simulations on MG-NG nanolaminate indicate an inverse Hall-Petch relationship for the nanolaminate strength versus MG volume fraction. Nanolaminates with NG layers separated by more than 50 nm fail by shear banding. In contrast, by closely packing NG layers, the nanolaminates exhibit superior tensile ductility regardless of the loading direction. Our work identifies the MG-NG nanolaminate structure with NG layers closely packed and interfaces oriented parallel to the loading direction as the most effective structure, preserving NG’s high ductility while still producing a 2.35 GPa strength. These results are expected to encourage the development of enhanced strong and ductile MG matrix composites.
Nanoglasses (NG), metallic glasses (MG) with a nanoscale grain structure, have the potential to considerably increase the ductility of traditional MG while preserving their outstanding mechanical properties. I will discuss results of molecular dynamics simulations of CuZr NG with grain sizes between 3 to 20 nm. Results indicate a transition from brittleness to ductility to nearly superplastic flow for decreasing grain size. Giving the outstanding ductility of NGs with nanometer grain sizes we consider their use in as promising material for the design of MG composites. The results of tensile loading simulations on MG-NG nanolaminate indicate an inverse Hall-Petch relationship for the nanolaminate strength versus MG volume fraction. Nanolaminates with NG layers separated by more than 50 nm fail by shear banding. In contrast, by closely packing NG layers, the nanolaminates exhibit superior tensile ductility regardless of the loading direction. Our work identifies the MG-NG nanolaminate structure with NG layers closely packed and interfaces oriented parallel to the loading direction as the most effective structure, preserving NG’s high ductility while still producing a 2.35 GPa strength. These results are expected to encourage the development of enhanced strong and ductile MG matrix composites.
Bio:
Paulo Branicio is currently an assistant professor at the University of Southern California (www.usc.edu) where he runs the Branicio Research Lab (branicio.usc.edu). He obtained his Ph.D. in Physics from the Federal University of São Carlos (UFSCar), São Carlos, Brazil. He was a Postdoc researcher at the Louisiana State University (LSU), and the University of Southern California, USA. During 2008-2016 he was an IHPC Independent Investigator and Scientist at the Institute of High Performance Computing (IHPC) – A*STAR, Singapore. In 2017, he joined USC as an Assistant Professor of Chemical Engineering and Materials Science. Paulo has co-authored over 60 peer-reviewed publications. His research interests include molecular dynamics simulations of metals and ceramics under extreme conditions, nanostructured hard ceramics, metallic glasses, phase change materials for data storage, and scalable parallel algorithms for data mining and structure analysis. He is part of the editorial board of Scientific Reports.
Paulo Branicio is currently an assistant professor at the University of Southern California (www.usc.edu) where he runs the Branicio Research Lab (branicio.usc.edu). He obtained his Ph.D. in Physics from the Federal University of São Carlos (UFSCar), São Carlos, Brazil. He was a Postdoc researcher at the Louisiana State University (LSU), and the University of Southern California, USA. During 2008-2016 he was an IHPC Independent Investigator and Scientist at the Institute of High Performance Computing (IHPC) – A*STAR, Singapore. In 2017, he joined USC as an Assistant Professor of Chemical Engineering and Materials Science. Paulo has co-authored over 60 peer-reviewed publications. His research interests include molecular dynamics simulations of metals and ceramics under extreme conditions, nanostructured hard ceramics, metallic glasses, phase change materials for data storage, and scalable parallel algorithms for data mining and structure analysis. He is part of the editorial board of Scientific Reports.
