Evaluation of strain caused by coherent precipitates in an Al alloy using TEM techniques

Hernández-Rivera, J.L.; Rivera, J.J. Cruz; Garay-Reyes, C.G.; Azpeitia, Mitsuo Ramos; Zúñiga-Alonso, I.; Martínez-Sánchez, R.

doi:10.1016/j.matchar.2012.07.017

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…Aluminum alloy precipitates which are only in nanometer range of diameter have established lattice-strains at precipitates-matrix interfaces due to the differences in lattice parameter value [9]. These lattice-strains caused distortion on crystal lattice structure which then prevent the dislocation motion of plane and consequently increase the alloy strength and hardness.…”

Section: Resultsmentioning

confidence: 99%

Alteration of Solution Treatment Condition to the Precipitation Behavior A319 Alloy

Darus

Jamaludin

Salleh

et al. 2013

AMR

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The development of precipitate during ageing treatment of A319 alloy contributed significantly to the alloy strengthening mechanism. Two solution treatment temperatures which were set at 510°C and 525°C were subjected onto the different groups of A319 alloy samples and followed by artificial ageing process at 180°C. Scanning electron microscopy was employed to observe the over-aged samples from both solution treatment temperatures. The observation shows that Mg2Si precipitates was only appeared at the higher solution treatment condition, while the Al2Cu precipitate developed in both solution treatment temperatures.

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Section: Resultsmentioning

confidence: 99%

Alteration of Solution Treatment Condition to the Precipitation Behavior A319 Alloy

Darus

Jamaludin

Salleh

et al. 2013

AMR

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“…The techniques for the quantitative evaluation of the displacement of atoms and related elastic strain developed by Hÿtch [203,204] and Galindo [205] provided remarkable progress in understanding the strain distribution in the microstructure, especially on the atomic scale. Thus far, there have been many reports on the characterization of elastic strain not only at the grain boundaries as twins [206] and dislocations at the grain boundaries [207][208][209] but also at the interphase boundary in the device [210], heterointerface at an epitaxially grown superlattice [211], and precipitate/matrix interfaces [212][213][214][215][216]. In addition to the strain (stress) field evaluated by the precise measurement of the displacement of atoms, the differential phase-contrast (DPC) imaging by a segmented detector [217] spread a new era in the visualization of electric [218,219] and magnetic fields [220] on an atomic scale.…”

Section: Prospects Of the Quantitative Characterization Of Interface ...mentioning

confidence: 99%

Quantitative Characterization by Transmission Electron Microscopy and Its Application to Interfacial Phenomena in Crystalline Materials

2024

Materials

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This paper reviews quantitative characterization via transmission electron microscopy (TEM) and its application to interfacial phenomena based on the results obtained through the studies. Several signals generated by the interaction between the specimen and the electron beam with a probe size of less than 1 nm are utilized for a quantitative analysis, which yields considerable chemical and physical information. This review describes several phenomena near the interfaces, e.g., clear solid–vapor interface (surface) segregation of yttria in the zirconia nanoparticles by an energy-dispersive X-ray spectroscopy analysis, the evaluation of the local magnetic moment at the grain boundary in terms of electron energy loss spectroscopy equipped with TEM, and grain boundary character dependence of the magnetism. The direct measurement of the stress to the dislocation transferred across the grain boundary and the microstructure evolution focused on the grain boundary formation caused by plastic deformation are discussed as examples of material dynamics associated with the grain boundary. Finally, the outlook for future investigations of interface studies, including the recent progress, is also discussed.

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“…Lower-resolution strain maps can be obtained by e.g. dark field imaging [12], dark-field holography [11] or (convergent) electron beam diffraction [13]. But hope is not lost for ADF-STEM: A methodology based on multi-frame exposures and alignment of the scan rows in each frame has proven to increase the positional accuracy up to the level of conventional TEM [14], without suffering effects such as uneven focus and contrast reversal.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, this otherwise superb imaging technique is plagued by scan distortions related to probe flyback, specimen drift, electronic noise and other environmental effects [8,9]. Accurate atomic positions are required for high-resolution strain measurements, and experimenters therefore typically resort to conventional high-resolution TEM imaging [10,11] or only measuring strain along the fast-scan direction in a STEM image when high precision is required. Lower-resolution strain maps can be obtained by e.g.…”

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confidence: 99%

Accurately measured precipitate–matrix misfit in an Al–Mg–Si alloy by electron microscopy

Wenner

Holmestad

2016

Scripta Materialia

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The age-hardenable Al-Mg-Si alloy system is strengthened by needle-shaped coherent β'' phase precipitates. Using distortion-corrected high-resolution scanning transmission electron microscopy images, we measure the considerable misfit between β'' particles and the Al matrix. The β'' phase is found to adapt its lattice parameters to the particle shape, distributing the strain in the Al matrix evenly in its cross-sectional plane. The measured misfits give a good match to reported atomistic simulations for a β'' phase with composition Mg5Al2Si4.Keywords: electron microscopy, aluminium alloys, precipitation, misfit strain 2 Coherent precipitates in age hardenable alloys and the misfit strain fields they induce in the surrounding matrix have been text book material for many decades [1]. Such precipitates form by thermally activated diffusion, nucleation and growth. A precipitate particle stays coherent until it grows too large for the matrix to accommodate all its misfit. After this, precipitates experience a loss of coherency, and the strain fields diminish, weakening the material. This can happen through several mechanisms:(i) a phase transformation to a less coherent phase (ii) formation of an incoherent surface layer at the matrix-precipitate interface (iii) introduction of interface (misfit) dislocations The precipitate phase can also relieve the system of some strain before coherency loss occurs by less drastic modifications:(iv) generation of stacking faults in the precipitate phase (v) chemical adjustments, including an increased vacancy density in or outside the precipitate phase All five effects can be studied using theoretical calculations such as density functional theory (DFT) or continuum mechanics through the finite element method (FEM). However, calculations need support by experiments at the atomic scale. Experimental studies require that we can both observe the causes (e.g. a single stacking fault) and quantify the resulting change in lattice strain. It is equally important to ensure the absence of faults, if the strain around a perfectly coherent particle is of interest.In this study, we focus on measuring the misfit of perfectly coherent β'' precipitates of the Al-Mg-Si system [2-4] through scanning transmission electron microscopy (STEM). This phase is described by the monoclinic C2/m space group and was initially thought to have composition Mg5Si6, but Mg5Al2Si4 is probably closer to the truth [5,6]. Its lattice parameters have been measured to a = 1.516 nm, b = 0.405 nm, c = 0.674 nm, and its monoclinic angle is 105.3° [2,3]. The phase was chosen since it is one of few fully coherent phases in aluminium alloys, and the main hardening phase of an industrially important alloy system. It is also needle-shaped with a long main coherency direction, often extending through the TEM specimen in which it resides. The lattice strain is therefore uniform through the specimen, and can be measured reliably in a projected image of a precipitate cross-section.When corrected for spherical aberratio...

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Evaluation of strain caused by coherent precipitates in an Al alloy using TEM techniques

Cited by 8 publications

References 23 publications

Alteration of Solution Treatment Condition to the Precipitation Behavior A319 Alloy

Alteration of Solution Treatment Condition to the Precipitation Behavior A319 Alloy

Quantitative Characterization by Transmission Electron Microscopy and Its Application to Interfacial Phenomena in Crystalline Materials

Accurately measured precipitate–matrix misfit in an Al–Mg–Si alloy by electron microscopy

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