Atomistic Studies of Deformation Mechanisms in Nanoscale Multilayered Metallic Composites PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Atomistic Studies of Deformation Mechanisms in Nanoscale Multilayered Metallic Composites PDF full book. Access full book title Atomistic Studies of Deformation Mechanisms in Nanoscale Multilayered Metallic Composites by Shuai Shao. Download full books in PDF and EPUB format.
Author: Shuai Shao
Publisher:
ISBN: 9781267477316
Category :
Languages : en
Pages :
Get Book Here
Book Description
The goal of this thesis is to understand the interaction between dislocations and various metallic interfaces in nanoscale metallic multilayers (NMM). At lower strain rates, this mean understanding the effect of interfaces to the strain hardening of the NMMs; at higher strain rates, this means the effect of the interfaces on the spallation strengths of the NMMs. NMMs possess ultra-high strength level which is owing to the interactions between single dislocations (i.e. no pile-up) and interfaces. In this thesis, aiming at the goal, using atomistic simulations several nanoscale metallic multilayers subjected to different loading conditions and strain rates are being considered.
Author: Shuai Shao
Publisher:
ISBN: 9781267477316
Category :
Languages : en
Pages :
Get Book Here
Book Description
The goal of this thesis is to understand the interaction between dislocations and various metallic interfaces in nanoscale metallic multilayers (NMM). At lower strain rates, this mean understanding the effect of interfaces to the strain hardening of the NMMs; at higher strain rates, this means the effect of the interfaces on the spallation strengths of the NMMs. NMMs possess ultra-high strength level which is owing to the interactions between single dislocations (i.e. no pile-up) and interfaces. In this thesis, aiming at the goal, using atomistic simulations several nanoscale metallic multilayers subjected to different loading conditions and strain rates are being considered.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Over the history of materials science there are many examples of materials discoveries that have made superlative materials; the strongest, lightest, or toughest material is almost always a goal when we invent new materials. However, often these have been a result of enormous trial and error approaches. A new methodology, one in which researchers design, from the atoms up, new ultra-strong materials for use in energy applications, is taking hold within the science and engineering community. This project focused on one particular new classification of materials; nanolaminate metallic composites. These materials, where two metallic materials are intimately bonded and layered over and over to form sheets or coatings, have been shown over the past decade to reach strengths over 10 times that of their constituents. However, they are not yet widely used in part because while extremely strong (they don't permanently bend), they are also not particularly tough (they break relatively easily when notched). Our program took a coupled approach to investigating new materials systems within the laminate field. We used computational materials science to explore ways to institute new deformation mechanisms that occurred when a tri-layer, rather than the more common bi-layer system was created. Our predictions suggested that copper-nickel or copper-niobium composites (two very common bi-layer systems) with layer thicknesses on the order of 20 nm and then layered 100's of times, would be less tough than a copper-nickel-niobium metallic composite of similar thicknesses. In particular, a particular mode of permanent deformation, cross-slip, could be activated only in the tri-layer system; the crystal structure of the other bi-layers would prohibit this particular mode of deformation. We then experimentally validated this predication using a wide range of tools. We utilized a DOE user facility, the Center for Integrated Nanotechnology (CINT), to fabricate, for the first time, these tri-layer composites. CINT formed nanolaminate composites were tested in tension, with bulge testing, using nanoindentation, and using micro-compression testing to demonstrate that the tri-layer films were indeed tougher and hardened more during deformation (they got stronger as we deformed them) than equivalent bi-layers. The seven graduate students, 4 post-docs and research faculty, and the two faculty co-PI's were able to create a collaborated computational prediction and experimental validation team to demonstrate the benefits of this class of materials to the community. The computational work crossed from atomistic to bulk simulations, and the experiments coupled form nm-scale to the mm scale; closely matching the simulations. The simulations provided viable mechanisms that explained the observed results, and new experimental results were used to push the boundaries of the simulation tools. Over the life of the 7 years of this program we proved that tri-layer nanolaminate metallic composite systems exceeded the mechanical performance of bi-layer systems if the right materials were chosen, and that the mechanism responsible for this was tied to the cross slip of dislocations. With 30 journal publications resulting from this work we have broadly disseminated this family of results to the scientific community.
Author: Firas Akasheh
Publisher:
ISBN: 9780549023258
Category :
Languages : en
Pages : 150
Get Book Here
Book Description
In this work, size effects and deformation mechanisms in nanoscale metallic multilayered (NMM) composites were studied. Existing models for the prediction of the dependence of strength of NMM composites on the individual layer thickness do not capture the experimentally observed dependence. Dislocation interactions have been suggested as a significant contributor to this discrepancy. Due to the complexity and multiplicity of dislocation interaction in real systems, the study started by examining the hardening effect and implications on the dislocation structure of two known-to-be significant dislocation interactions in NMM composites. The first is the interaction between a threading dislocation and orthogonally intersection interfacial dislocations. Dislocation dynamics (DD) analysis was employed and it was found that the strongest interaction occurs when the interacting dislocations are collinear and involves annihilation reactions and the formation of 90° dislocation bends at the interfaces, as commonly observed in experiments. The strength predictions indicate a strengthen increase of about 50%; however, they do not follow the experimentally observed trend. The second interaction to study was that between a threading dislocation and parallel interfacial dislocations. A semi-analytical energetic approach was employed and it was found that parallel interactions can lead to softening effect, as well as hardening effect depending on the relative sign of the Burgers vector of the threading and the parallel dislocations. It was also found that when the Burgers vectors are collinear, the interaction is stronger. A comparison with the measured strength of real multilayered system shows that accounting for parallel interactions improves the strength predictions for an isolated glide dislocation, however that does not offer answers regarding the observed strength saturation when the individual layer thickness in the few nanometer range. Finally, large-scale DD simulations of NMM composites were performed. Such simulations naturally accounts for all the possible and complex interactions in a real system. The strength predictions of such simulations are in better qualitative agreement with experimental trends than any of the unit process. Nevertheless, more work is needed to validate the results by investigating different relaxation models to accomplish the initial dislocations structure used in subsequent loading. The simulations were also valuable in identifying dislocation mechanisms which can take place during the deformation.
Author: Niaz Abdolrahim
Publisher:
ISBN: 9781303240348
Category :
Languages : en
Pages :
Get Book Here
Book Description
The objective of this research is to investigate the deformation behaviors of two types of NMMs at lower length scales: 1) One dimensional Cu-Ni, Au-Ni nanowires with coherent interfaces and 2) Two dimensional Cu-Nb multilayers with incoherent interfaces.
Author: Adrien Gola
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Julia R. Greer
Publisher: Materials Research Society
ISBN: 9781605112749
Category : Technology & Engineering
Languages : en
Pages : 0
Get Book Here
Book Description
Symposium P, "Deformation Mechanisms, Microstructure Evolution, and Mechanical Properties of Nanoscale Materials," was held Nov. 29-Dec. 3 at the 2010 MRS Fall Meeting in Boston, Massachusetts. This resultant volume addresses the topic of materials used in next-generation technological devices. These devices are used for a variety of applications-ranging from biomedical to space to energy-related-and will be subjected to non-ambient temperatures and high stresses and pressures. A variety of advanced nanomaterials and nanoscaled architectures have been proposed to meet these stringent demands. However, a complete understanding of the mechanisms that govern deformation at these scales is still elusive. This volume focuses on providing the state-of-the-art research on the mechanical response of nano- and microscale components that may comprise these devices and highlights emerging topics in novel mechanical testing techniques, in situ microscopy, high- and low-temperature deformation mechanisms, and mechanical property characterization of materials, as well as recent advances in atomistic and multiscale modeling of nanomaterials.
Author: The Minerals, Metals & Materials Society (TMS)
Publisher: John Wiley & Sons
ISBN: 1119093481
Category : Technology & Engineering
Languages : en
Pages : 1584
Get Book Here
Book Description
The TMS 2015 Annual Meeting Supplemental Proceedings is a collection of papers from the TMS 2015 Annual Meeting & Exhibition, held March 15-19 in Orlando, Florida, USA. The papers in this volume represent 33 symposia from the meeting. This volume, along with the other proceedings volumes published for the meeting, and archival journals, such as Metallurgical and Materials Transactions and Journal of Electronic Materials, represents the available written record of the 73 symposia held at TMS2015. This proceedings volume contains both edited and unedited papers; the unedited papers have not necessarily been reviewed by the symposium organizers and are presented "as is." The opinions and statements expressed within the papers are those of the individual authors only, and no confirmations or endorsements are intended or implied.
Author: The Minerals, Metals & Materials Society (TMS)
Publisher: Springer
ISBN: 3319481274
Category : Technology & Engineering
Languages : en
Pages : 1496
Get Book Here
Book Description
Author: Christian Brandl
Publisher:
ISBN:
Category :
Languages : en
Pages : 123
Get Book Here
Book Description
Author: La Vern Starman
Publisher: Springer
ISBN: 3319422286
Category : Technology & Engineering
Languages : en
Pages : 79
Get Book Here
Book Description
Micro-and Nanomechanics, Volume 5 of the Proceedings of the 2016 SEM Annual Conference & Exposition on Experimental and Applied Mechanics, the fifth volume of ten from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on a wide range of areas, including: MEMS: Materials & Interfaces Microscale & Microstructural Effects on Mechanical Behavior Novel Nano-scale Probes Nanoindentation & Beyond Nanomechanics Dynamic Micro/Nano Mechanics
