Special Issue "Crystal Indentation Hardness"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystal Engineering".

Deadline for manuscript submissions: closed (30 September 2017)

Special Issue Editors

Guest Editor
Prof. Dr. Ronald W. Armstrong

Department of Mechanical Engineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA
Website | E-Mail
Interests: crystal dislocations; x-ray diffraction imaging; polycrystalline microstructures; mechanical properties; constitutive equations
Guest Editor
Dr. Stephen M. Walley

Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
Website | E-Mail
Interests: high rate deformation; history of mechanical testing of materials; energetic crystals and polymers
Guest Editor
Prof. Dr. Wayne L. Elban

Department of Engineering, Loyola University Maryland, Baltimore, MD 21210, USA
Website | E-Mail
Interests: mechanical properties; indentation hardness; microstructural characterization; historical ferrous metallurgy

Special Issue Information

Dear Colleagues,

Determinations of the indentation hardness properties of crystals have expanded to cover the full characterizations of their important elastic, plastic and cracking behaviors, particularly as accomplished with the increased measuring capabilities of nanoindentation hardness testing. No crystal structure of any bonding type is either too soft or too hard to prevent measurement with a suitable probing indenter. The current Special Issue is devoted to surveying the topic with emphasis given in a collection of reports to: (1) the diversity of crystals being tested; (2) the variety of measuring techniques; and (3) the wealth of information being obtained.

Prof. Dr. Ron Armstrong
Prof. Dr. Stephen Walley
Prof. Dr. Wayne L. Elban
Guest Editors

Manuscript Submission Information

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Keywords

  • indentation hardness
  • nanoindentation testing
  • elastic loading
  • plastic deformation
  • indentation fracture mechanics

Published Papers (7 papers)

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Editorial

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Open AccessEditorial Crystal Indentation Hardness
Crystals 2017, 7(1), 21; doi:10.3390/cryst7010021
Received: 5 January 2017 / Accepted: 6 January 2017 / Published: 12 January 2017
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Abstract
There is expanded interest in the long-standing subject of the hardness properties of materials. A major part of such interest is due to the advent of nanoindentation hardness testing systems which have made available orders of magnitude increases in load and displacement measuring
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There is expanded interest in the long-standing subject of the hardness properties of materials. A major part of such interest is due to the advent of nanoindentation hardness testing systems which have made available orders of magnitude increases in load and displacement measuring capabilities achieved in a continuously recorded test procedure. The new results have been smoothly merged with other advances in conventional hardness testing and with parallel developments in improved model descriptions of both elastic contact mechanics and dislocation mechanisms operative in the understanding of crystal plasticity and fracturing behaviors. No crystal is either too soft or too hard to prevent the determination of its elastic, plastic and cracking properties under a suitable probing indenter. A sampling of the wealth of measurements and reported analyses associated with the topic on a wide variety of materials are presented in the current Special Issue. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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Research

Jump to: Editorial, Review

Open AccessArticle Atomistic Studies of Nanoindentation—A Review of Recent Advances
Crystals 2017, 7(10), 293; doi:10.3390/cryst7100293
Received: 12 September 2017 / Revised: 25 September 2017 / Accepted: 26 September 2017 / Published: 29 September 2017
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Abstract
This review covers areas where our understanding of the mechanisms underlying nanoindentation has been increased by atomistic studies of the nanoindentation process. While such studies have been performed now for more than 20 years, recent investigations have demonstrated that the peculiar features of
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This review covers areas where our understanding of the mechanisms underlying nanoindentation has been increased by atomistic studies of the nanoindentation process. While such studies have been performed now for more than 20 years, recent investigations have demonstrated that the peculiar features of nanoplasticity generated during indentation can be analyzed in considerable detail by this technique. Topics covered include: nucleation of dislocations in ideal crystals, effect of surface orientation, effect of crystallography (fcc, bcc, hcp), effect of surface and bulk damage on plasticity, nanocrystalline samples, and multiple (sequential) indentation. In addition we discuss related features, such as the influence of tip geometry on the indentation and the role of adhesive forces, and how pre-existing plasticity affects nanoindentation. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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Open AccessArticle Mechanical Anisotropy in Austenitic NiMnGa Alloy: Nanoindentation Studies
Crystals 2017, 7(8), 254; doi:10.3390/cryst7080254
Received: 23 June 2017 / Revised: 14 August 2017 / Accepted: 15 August 2017 / Published: 17 August 2017
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Abstract
Abstract: Mechanical anisotropy in an austenitic ferromagnetic shape memory alloy (SMA), Ni50Mn26.25Ga23.75, is investigated along (010), (120), (121), (231) and (232) using nanoindentation. While (010) exhibits the highest reduced modulus, Er, and hardness, H
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Abstract: Mechanical anisotropy in an austenitic ferromagnetic shape memory alloy (SMA), Ni50Mn26.25Ga23.75, is investigated along (010), (120), (121), (231) and (232) using nanoindentation. While (010) exhibits the highest reduced modulus, Er, and hardness, H, (232) shows the lowest amongst the grain orientations examined in this study. The significant elastic anisotropy measured is attributed to differences in planar packing density and number of in-plane Ni–Mn and Ni–Ga bonds, whereas the plastic anisotropy is due to the differences in the onset of slip, which is rationalized by recourse to Schmid factor calculations. This would help determine the grain orientations in austenitic NiMnGa which exhibit better mechanical properties for SMA applications such as improving vibration damping characteristics of the alloy. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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Open AccessArticle Atomistic Insights into the Effects of Residual Stress during Nanoindentation
Crystals 2017, 7(8), 240; doi:10.3390/cryst7080240
Received: 21 June 2017 / Revised: 26 July 2017 / Accepted: 30 July 2017 / Published: 1 August 2017
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Abstract
The influence of in-plane residual stress on Hertzian nanoindentation for single-crystal copper thin film is investigated using molecular dynamics simulations (MD). It is found that: (i) the yield strength of incipient plasticity increases with compressive residual stress, but decreases with tensile residual stress;
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The influence of in-plane residual stress on Hertzian nanoindentation for single-crystal copper thin film is investigated using molecular dynamics simulations (MD). It is found that: (i) the yield strength of incipient plasticity increases with compressive residual stress, but decreases with tensile residual stress; (ii) the hardness decreases with tensile residual stress, and increases with compressive residual stress, but abruptly drops down at a higher compressive residual stress level, because of the deterioration of the surface; (iii) the indentation modulus reduces linearly with decreasing compressive residual stress (and with increasing tensile residual stress). It can be concluded from the MD simulations that the residual stress not only strongly influences the dislocation evolution of the plastic deformation process, but also significantly affects the size of the plastic zone. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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Open AccessArticle Theoretical Study on Electronic, Optical Properties and Hardness of Technetium Phosphides under High Pressure
Crystals 2017, 7(6), 176; doi:10.3390/cryst7060176
Received: 4 April 2017 / Revised: 18 May 2017 / Accepted: 15 June 2017 / Published: 18 June 2017
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Abstract
In this paper, the structural properties of technetium phosphides Tc3P and TcP4 are investigated by first principles at zero pressure and compared with the experimental values. In addition, the electronic properties of these two crystals in the pressure range of
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In this paper, the structural properties of technetium phosphides Tc3P and TcP4 are investigated by first principles at zero pressure and compared with the experimental values. In addition, the electronic properties of these two crystals in the pressure range of 0–40 GPa are investigated. Further, we discuss the change in the optical properties of technetium phosphides at high pressures. At the end of our study, we focus on the research of the hardness of TcP4 at different pressures by employing a semiempirical method, and the effect of pressure on the hardness is studied. Results show that the hardness of TcP4 increases with the increasing pressure, and the influence mechanism of pressure effect on the hardness of TcP4 is also discussed. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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Open AccessArticle Application of the Improved Inclusion Core Model of the Indentation Process for the Determination of Mechanical Properties of Materials
Crystals 2017, 7(3), 87; doi:10.3390/cryst7030087
Received: 9 February 2017 / Revised: 7 March 2017 / Accepted: 14 March 2017 / Published: 16 March 2017
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Abstract
The improved Johnson inclusion core model of indentation by conical and pyramidal indenters in which indenter is elastically deformed and a specimen is elastoplastically deformed under von Mises yield condition, was used for determination of mechanical properties of materials with different types of
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The improved Johnson inclusion core model of indentation by conical and pyramidal indenters in which indenter is elastically deformed and a specimen is elastoplastically deformed under von Mises yield condition, was used for determination of mechanical properties of materials with different types of interatomic bond and different crystalline structures. This model enables us to determine approximately the Tabor parameter С = НМ/YS (where НМ is the Meyer hardness and YS is the yield stress of the specimen), size of the elastoplastic zone in the specimen, effective apex angle of the indenter under load, and effective angle of the indent after unloading. It was shown that the Tabor parameter and the size of elastoplastic deformation zone increase monotonically with the increase of the plasticity characteristic indentation test results significantly more informative. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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Review

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Open AccessReview Progress in Indentation Study of Materials via Both Experimental and Numerical Methods
Crystals 2017, 7(10), 258; doi:10.3390/cryst7100258
Received: 19 June 2017 / Revised: 8 August 2017 / Accepted: 9 August 2017 / Published: 13 October 2017
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Abstract
Indentation as a method to characterize materials has a history of more than 117 years. However, to date, it is still the most popular way to measure the mechanical properties of various materials at microscale and nanoscale. This review summarizes the background and
[...] Read more.
Indentation as a method to characterize materials has a history of more than 117 years. However, to date, it is still the most popular way to measure the mechanical properties of various materials at microscale and nanoscale. This review summarizes the background and the basic principle of processing by indentation. It is demonstrated that indentation is an effective and efficient method to identify mechanical properties, such as hardness, Young’s modulus, etc., of materials at smaller scale, when the traditional tensile tests could not be applied. The review also describes indentation process via both experimental tests and numerical modelling in recent studies. Full article
(This article belongs to the Special Issue Crystal Indentation Hardness)
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