Size Effects in Metals and Alloys and Impact on the Miniaturization of Metallic Parts

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (20 July 2019) | Viewed by 6009

Special Issue Editor


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Guest Editor
CRISMAT Laboratory, UMR 6508, Normandy University, 6 Boulevard Marechal Juin, CEDEX 4, 14050 Caen, France
Interests: plasticity mechanisms; plasticity modelisation; dislocations and twinning; size effects in metals; corrosion; magnetic and electrical properties; spark plasma sintering; additive manufacturing
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Special Issue Information

Dear Colleagues,

The forming process of thin parts for miniaturized systems, used in engineering, medical or electrical devices, is often a technological challenge due to the influence of free surfaces on the mechanical properties of the material. It is well established that the manufacturing of microformed components is concerned with size effects, proceeding from dimensional or microstructural length scales. The accuracy and reliability of electronic miniaturized parts can be, therefore, strongly affected by these kinds of size effects. The transition from micro-sized samples to nano-sized ones leads to a “smaller is stronger” effect, widely characterized for micropillars and thin films. From macro specimens to microsized specimens, a “smaller is softer” trend, which is less investigated, is generally observed for metallic materials.

Main of published works on size effects deal with their impact on the mechanical properties: work hardening, fracture and damage mechanisms. Others properties of metals, and their evolutions with such size effects, are far less studied. For instance, the impact of miniaturization on magnetomechanical couplings deserves attention because such effects can deeply modify the ferromagnetic properties of thin metallic parts used in magnetic microsensors. Others metal properties are also of deeply impacted by miniaturization: electrical properties, thermal fluctuations, formability, corrosion and degradation, and all coupled phenomenon between two or more properties.

This Special Issue seeks to provide a selection of original research on the current trends in size effects in metallic parts. Submissions dealing with microformability and consequences on structural and functional properties are welcome. As a Guest Editor of this Special Issue, I invite you to submit your work, which will be peer-reviewed, to be accepted for publication in Metals.

Prof. Dr. Eric Hug
Guest Editor

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Keywords

  • Size effects
  • Miniaturization
  • Mechanical behaviour
  • Functional properties
  • Multiphysical couplings
  • Formability
  • Sensors

Published Papers (2 papers)

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Research

11 pages, 3181 KiB  
Article
A Surface Transition Layer Model for Size Effect in T2 Copper Micro-Compression
by Lei Deng, Wei Liu, Xinyun Wang and Junsong Jin
Metals 2019, 9(7), 736; https://doi.org/10.3390/met9070736 - 29 Jun 2019
Cited by 1 | Viewed by 2055
Abstract
The effects of sample size and grain size on the surface morphology and flow stress of deformed samples were investigated by means of copper micro-cylinder compression experiments at room temperature. The results of SEM showed that when the grain size increased or the [...] Read more.
The effects of sample size and grain size on the surface morphology and flow stress of deformed samples were investigated by means of copper micro-cylinder compression experiments at room temperature. The results of SEM showed that when the grain size increased or the sample size decreased, the deformation non-uniformity of samples’ free surfaces increased. Meanwhile, the stress–strain curves showed that during the compression process, the flow stress of the sample also tended to decrease as the grain size increased or the sample size decreased. According to the experimental results of nanoindentation, a surface transition layer model was established on the basis of the surface layer model by considering the mutual constraint of grains and the existence of transition layer grains. The experimental results indicated that the stress–strain curve calculated by the surface transition layer model can more accurately reflect the actual deformation situation of the material compared to the surface layer model. Full article
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9 pages, 282 KiB  
Communication
A Brief Note on the Nix–Gao Strain Gradient Plasticity Theory
by A. S. Borokinni and Dabiao Liu
Metals 2018, 8(9), 708; https://doi.org/10.3390/met8090708 - 10 Sep 2018
Cited by 1 | Viewed by 3449
Abstract
The mathematical nature of the flow rule for the strain gradient plasticity theory proposed by Nix and Gao (W.D. Nix and H. Gao, J Mech Phys Solids 46(3), 411(1998)) is discussed based on the paradigm developed by Gurtin and Anand (M.E. Gurtin and [...] Read more.
The mathematical nature of the flow rule for the strain gradient plasticity theory proposed by Nix and Gao (W.D. Nix and H. Gao, J Mech Phys Solids 46(3), 411(1998)) is discussed based on the paradigm developed by Gurtin and Anand (M.E. Gurtin and L. Anand, J Mech Phys Solids 57 (3), 405 (2009)). It is shown that, when investigated on the basis of Gurtin–Anand theory, the Nix–Gao flow rule is a combination of constitutive equations for microstresses, balance law, and a constraint. As an accessory, we demonstrate that the strain gradient term introduced in the model is energetic. The results are obtained by combining a virtual-power principle of Fleck and Hutchinson, and the free-energy imbalance under isothermal conditions. Full article
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