Measuring Structural Heterogeneities in Metallic Glasses Using Transmission Electron Microscopy

Tian, Lin; Volkert, Cynthia A.

doi:10.3390/met8121085

Cited by 11 publications

(5 citation statements)

References 88 publications

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“…Pekin et al (2018) have extended this method to in-situ heating experiments for a Cu–Zr–Al metallic glass, and Im et al (2018) have measured the degree of local ordering for different angular symmetries in a Zr–Co–Al glass, both using modern 4D-STEM cameras capable of recording a large amount of data with good statistics. A review of TEM measurements of heterogeneity in metallic glasses has been published by Tian & Volkert (2018).…”

Section: Structure and Property Measurementsmentioning

confidence: 99%

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

2019

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Scanning transmission electron microscopy (STEM) is widely used for imaging, diffraction, and spectroscopy of materials down to atomic resolution. Recent advances in detector technology and computational methods have enabled many experiments that record a full image of the STEM probe for many probe positions, either in diffraction space or real space. In this paper, we review the use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping, measurements of medium-range order, thickness and tilt of samples, and phase contrast imaging methods, including differential phase contrast, ptychography, and others.

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Section: Structure and Property Measurementsmentioning

confidence: 99%

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

2019

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“…For instance, atomic simulations have pointed out a medium range order called soft spots that could explain the glass mechanical behaviour [29], [30]. Unfortunately because of the amorphous structure direct evidences for these soft spots are difficult to obtain [31]. To that respect, eutectic mixture involving a CMA phase could provide attractive model systems since, as pointed out by the corrugated layer described above, the tetrahedral local order of CMA phases makes them quite isotropic and from that point of view close to an amorphous alloy.…”

Section: Discussionmentioning

confidence: 99%

Deformation of Mg-γMg17Al12 in situ composites: Room temperature mechanical behaviour, microstructures and mechanisms

Donnadieu¹,

Benrhaiem²,

Renou³

et al. 2021

Intermetallics

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Deformation tests at room temperature have been carried out on a series of in situ Mg-Mg17Al12 composites with volume fraction of Mg17Al12 phase varying between 20 % and 60%. Regardless of the phase volume fraction, these Mg-Mg17Al12 composites that are prepared by solidification consist in magnesium-rich dendrites and a eutectic mixture. The eutectic mixture is made of magnesium fibres embedded in a matrix formed by the Mg17Al12 phase, a hard and brittle complex metallic alloy. Compression tests at room temperature have shown that a global plastic deformation is observed even though the soft phase is always enclosed in the brittle one. According to the strain-stress curve, deformation proceeds in two stages: a first stage at low stress (~ 100 MPa) and low strain ( < 0.01) almost similar for all the composites and a second stage characterized by a strain hardening effect along with a significant deformation for composites with  phase volume fraction smaller than 40 %, whereas no or little additional deformation is observed for composites with volume fraction higher than 40% that break at high stress (~ 400 MPa). Microstructural observations of the deformed samples have evidenced dislocations in the Mg17Al12 matrix and their localisation as pile-ups and slip bands as well as the transmission of deformation across the eutectic mixture. The plasticity of the Mg17Al12 phase and the mechanical behaviour of the Mg-Mg17Al12 composites are discussed with respect to the microstructure characteristics and to the specific atomic features of complex metallic alloy phases.

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“…Various experimental and simulation methods were employed to investigate the heterogeneity in MGs at different length scales [7][8][9][10][11]. For instance, synchrotron X-ray diffraction (XRD) was used to explore the averaged structural heterogeneity at the atomic scale [8,12], and high-resolution transmission electron microscopy (HRTEM) was used to detect the nanometer scale density fluctuation in MGs [11,13,14]. In recent years, with the development of nanomechanical testing instruments, spatial heterogeneity was also characterized using the fluctuations of local mechanical properties via two-dimensional (2D) atomic force microscopy (AFM) mapping at the nanoscale [9,10,15] or nanoindentation mapping at the sub-micro-and microscale [16,17].…”

Section: Introductionmentioning

confidence: 99%

Spatial Resolution Limit for Nanoindentation Mapping on Metallic Glasses

et al. 2022

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Spatial heterogeneity, as a crucial structural feature, has been intensively studied in metallic glasses (MGs) using various techniques, including two-dimensional nanoindentation mapping. However, the limiting spatial resolution of nanoindentation mapping on MGs remains unexplored. In this study, a comprehensive study on four representative MGs using nanoindentation mapping with a Berkovich indenter was carried out by considering the influence of a normalized indentation spacing d/h (indentation spacing/maximum indentation depth). It appeared to have no significant correlation with the measured hardness and elastic modulus when d/h > 10. The hardness and elastic modulus started to increase slightly (up to ~5%) when d/h < 10 and further started to decrease obviously when d/h < 5. The mechanism behind these phenomena was discussed based on a morphology analysis of residual indents using scanning electron microscopy and atomic force microscopy. It was found that the highest spatial resolution of ~200 nm could be achieved with d/h = 10 using a typical Berkovich indenter for nanoindentation mapping on MGs, which was roughly ten times the curvature radius of the Berkovich indenter tip (not an ideal triangular pyramid) used in this study. These results help to promote the heterogeneity studies of MGs using nanoindentation that are capable of covering a wide range of length scales with reliable and consistent results.

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Measuring Structural Heterogeneities in Metallic Glasses Using Transmission Electron Microscopy

Cited by 11 publications

References 88 publications

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

Deformation of Mg-γMg17Al12 in situ composites: Room temperature mechanical behaviour, microstructures and mechanisms

Spatial Resolution Limit for Nanoindentation Mapping on Metallic Glasses

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