Showing papers on "Grain boundary published in 2014"
TL;DR: This controllable self-induced passivation technique for perovskite films is demonstrated, which enables their compositional change, and allows substantial enhancement in corresponding device performance.
Abstract: To improve the performance of the polycrystalline thin film devices, it requires a delicate control of its grain structures. As one of the most promising candidates among current thin film photovoltaic techniques, the organic/inorganic hybrid perovskites generally inherit polycrystalline nature and exhibit compositional/structural dependence in regard to their optoelectronic properties. Here, we demonstrate a controllable passivation technique for perovskite films, which enables their compositional change, and allows substantial enhancement in corresponding device performance. By releasing the organic species during annealing, PbI2 phase is presented in perovskite grain boundaries and at the relevant interfaces. The consequent passivation effects and underlying mechanisms are investigated with complementary characterizations, including scanning electron microscopy (SEM), X-ray diffraction (XRD), time-resolved photoluminescence decay (TRPL), scanning Kelvin probe microscopy (SKPM), and ultraviolet photoemi...
1,298 citations
20 Oct 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of the microstructure on the tensile properties of additive manufacturing (AM) of Ti alloys has been investigated. And the authors found that the mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms.
Abstract: Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V.
671 citations
TL;DR: Grain boundary complexion transitions are the root cause of a wide variety of materials phenomena such as abnormal grain growth, grain boundary embrittlement and activated sintering as discussed by the authors, which have defied mechanistic explanation for years.
662 citations
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TL;DR: The monolayer film is composed of coalescing single islands with limited numbers of lattice orientation due to an epitaxial growth mechanism, and local potential mapping along channels in field-effect transistors shows that the single-crystal MoS2 grains in the film are well connected, with interfaces that do not degrade the electrical conductivity.
Abstract: Two-dimensional semiconductors such as MoS2 are an emerging material family with wide-ranging potential applications in electronics, optoelectronics and energy harvesting. Large-area growth methods are needed to open the way to the applications. While significant progress to this goal was made, control over lattice orientation during growth still remains a challenge. This is needed in order to minimize or even avoid the formation of grain boundaries which can be detrimental to electrical, optical and mechanical properties of MoS2 and other 2D semiconductors. Here, we report on the uniform growth of high-quality centimeter-scale continuous monolayer MoS2 with control over lattice orientation. Using transmission electron microscopy we show that the monolayer film is composed of coalescing single islands that share a predominant lattice orientation due to an epitaxial growth mechanism. Raman and photoluminescence spectra confirm the high quality of the grown material. Optical absorbance spectra acquired over large areas show new features in the high-energy part of the spectrum, indicating that MoS2 could also be interesting for harvesting this region of the solar spectrum and fabrication of UV-sensitive photodetectors. Even though the interaction between the growth substrate and MoS2 is strong enough to induce lattice alignment, we can easily transfer the grown material and fabricate field-effect transistors on SiO2 substrates showing mobility superior to the exfoliated material.
604 citations
TL;DR: In this article, loss mechanisms are systematically investigated and mitigated in solar cells based on p-type tin monosulfide, SnS, absorber layers combined with n-type zinc oxysulfide and Zn(O,S) layers that selectively transmit electrons, but block holes.
Abstract: Thin-film solar cells are made by vapor deposition of Earth-abundant materials: tin, zinc, oxygen and sulfur. These solar cells had previously achieved an efficiency of about 2%, less than 1/10 of their theoretical potential. Loss mechanisms are systematically investigated and mitigated in solar cells based on p-type tin monosulfide, SnS, absorber layers combined with n-type zinc oxysulfide, Zn(O,S) layers that selectively transmit electrons, but block holes. Recombination at grain boundaries is reduced by annealing the SnS films in H2S to form larger grains with fewer grain boundaries. Recombination near the p-SnS/n-Zn(O,S) junction is reduced by inserting a few monolayers of SnO2 between these layers. Recombination at the junction is also reduced by adjusting the conduction band offset by tuning the composition of the Zn(O,S), and by reducing its free electron concentration with nitrogen doping. The resulting cells have an efficiency over 4.4%, which is more than twice as large as the highest efficiency obtained previously by solar cells using SnS absorber layers.
491 citations
TL;DR: In this article, the authors proposed a solute decoration approach to manipulate specific grain boundary structures, compositions and properties that enable useful material behavior, such as energy, mobility, structure, and cohesion.
Abstract: a b s t r a c t Grain boundaries influence mechanical, functional, and kinetic properties of metallic alloys. They can be manipulated via solute decoration enabling changes in energy, mobility, structure, and cohesion or even promoting local phase transformation. In the approach which we refer here to as ‘segregation engineering’ solute decoration is not regarded as an undesired phenomenon but is instead utilized to manipulate specific grain boundary structures, compositions and properties that enable useful material behavior. The underlying thermodynamics follow the adsorption isotherm. Hence, matrix-solute combinations suited for designing interfaces in metallic alloys can be identified by considering four main aspects, namely, the segregation coefficient of the decorating element; its effects on interface cohesion, energy, structure and mobility; its diffusion coefficient; and the free energies of competing bulk phases, precipitate phases or complexions. From a practical perspective, segregation engineering in alloys can be usually realized by a modest diffusion heat treatment, hence, making it available in large scale manufacturing.
470 citations
TL;DR: A review of the large body of research reported in the past few years on polycrystalline graphene, which discusses its growth and formation, the microscopic structure of grain boundaries and their relations to other types of topological defect such as dislocations.
Abstract: This Review discusses the recent experimental and theoretical findings on polycrystalline graphene and related materials. Graphene, a single atomic layer of graphitic carbon, has attracted intense attention because of its extraordinary properties that make it a suitable material for a wide range of technological applications. Large-area graphene films, which are necessary for industrial applications, are typically polycrystalline — that is, composed of single-crystalline grains of varying orientation joined by grain boundaries. Here, we present a review of the large body of research reported in the past few years on polycrystalline graphene. We discuss its growth and formation, the microscopic structure of grain boundaries and their relations to other types of topological defect such as dislocations. The Review further covers electronic transport, optical and mechanical properties pertaining to the characterizations of grain boundaries, and applications of polycrystalline graphene. We also discuss research, still in its infancy, performed on other two-dimensional materials such as transition metal dichalcogenides, and offer perspectives for future directions of research.
422 citations
TL;DR: In this paper, the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3 was investigated.
Abstract: We report on the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3. The comparable absolute values and temperature dependence of the two samples’ morphologies indicate the minor role of the grain boundaries on the heat transport. Theoretical modeling demonstrates the importance of the resonant scattering in both specimens. The interaction between phonon waves and rotational degrees of freedom of CH3NH3+ sublattice emerges as the dominant mechanism for attenuation of heat transport and for ultralow thermal conductivity of 0.5 W/(Km) at room temperature.
414 citations
TL;DR: At atomic-scale images, it is demonstrated directly that the evolution of the misorientation angle between neighbouring grains can be quantitatively accounted for by the change of the Frank–Bilby dislocation content in the grain boundary.
Abstract: Grain rotation is a well-known phenomenon during high (homologous) temperature deformation and recrystallization of polycrystalline materials. In recent years, grain rotation has also been proposed as a plasticity mechanism at low temperatures (for example, room temperature for metals), especially for nanocrystalline grains with diameter d less than ~15 nm. Here, in tensile-loaded Pt thin films under a high-resolution transmission electron microscope, we show that the plasticity mechanism transitions from cross-grain dislocation glide in larger grains (d>6 nm) to a mode of coordinated rotation of multiple grains for grains with d<6 nm. The mechanism underlying the grain rotation is dislocation climb at the grain boundary, rather than grain boundary sliding or diffusional creep. Our atomic-scale images demonstrate directly that the evolution of the misorientation angle between neighbouring grains can be quantitatively accounted for by the change of the Frank–Bilby dislocation content in the grain boundary. Grain rotation is proposed as an active deformation mechanism in nanocrystalline metals at room temperature. Here, during in-situatomic scale experimentation, the authors observe that grains with a size <6 nm deform by coordinated rotation of multiple grains, associated with dislocation climb at grain boundaries.
313 citations
TL;DR: In this article, a linear trend between carbon segregation and the misorientation angle ω was found for low-angle grain boundaries in ferrite, which indicates that ω is the most influential crystallographic parameter in this regime.
Abstract: Grain boundary segregation leads to nanoscale chemical variations that can alter a material's performance by orders of magnitude (e.g., embrittlement). To understand this phenomenon, a large number of grain boundaries must be characterized in terms of both their five crystallographic interface parameters and their atomic-scale chemical composition. We demonstrate how this can be achieved using an approach that combines the accuracy of structural characterization in transmission electron microscopy with the 3D chemical sensitivity of atom probe tomography. We find a linear trend between carbon segregation and the misorientation angle ω for low-angle grain boundaries in ferrite, which indicates that ω is the most influential crystallographic parameter in this regime. However, there are significant deviations from this linear trend indicating an additional strong influence of other crystallographic parameters (grain boundary plane, rotation axis). For high-angle grain boundaries, no general trend between carbon excess and ω is observed; i.e., the grain boundary plane and rotation axis have an even higher influence on the segregation behavior in this regime. Slight deviations from special grain boundary configurations are shown to lead to unexpectedly high levels of segregation.
284 citations
TL;DR: In this article, a review of recent progress in understanding dislocation interactions with grain boundaries and interfaces in metallic systems via static and in situ dynamic experimental approaches is reviewed, as well as a comparison of different experimental approaches.
Abstract: Recent progress in understanding dislocation interactions with grain boundaries and interfaces in metallic systems via static and in situ dynamic experimental approaches is reviewed.
TL;DR: The growth and characterization of novel large area h-BN hexagons using highly electropolished Cu substrate under atmospheric pressure CVD conditions are reported and it is found that the nucleation density ofh-BN is significantly reduced while domain sizes increase.
Abstract: Hexagonal-boron nitride (h-BN) or “white graphene” has many outstanding properties including high thermal conductivity, high mechanical strength, chemical inertness, and high electrical resistance, which open up a wide range of applications such as thermal interface material, protective coatings, and dielectric in nanoelectronics that easily exceed the current advertised benefits pertaining to the graphene-based applications. The development of h-BN films using chemical vapor deposition (CVD) has thus far led into nucleation of triangular or asymmetric diamond shapes on different metallic surfaces. Additionally, the average size of the triangular domains has remained relatively small (∼0.5 μm2) leading to a large number of grain boundaries and defects. While the morphology of Cu surfaces for CVD-grown graphene may have impacts on the nucleation density, domain sizes, thickness, and uniformity, the effects of the decreased roughness of Cu surface to develop h-BN films are unknown. Here, we report the growt...
TL;DR: In this paper, a systematic review of the development of these lead-free composite solders is given, which hopefully may find applications in microbumps to be used in the future 3D IC technology.
Abstract: Composite lead-free solders, containing micro and nano particles, have been widely studied. Due to grain boundary drag or Zener drag, these particles can refrain the solder microstructure from coarsening in services, especially for Cu6Sn5, Ag3Sn intermetallic compounds and the β-Sn phases. Due to dispersion hardening or dislocation drag, the mechanical properties of the composite solder alloys were enhanced significantly. Moreover, these particles can influence the rate of interfacial reactions, and some particles can transform into a layer of intermetallic compound. Wettability, creep resistance, and hardness properties were affected by these particles. A systematic review of the development of these lead-free composite solders is given here, which hopefully may find applications in microbumps to be used in the future 3D IC technology.
TL;DR: Density functional calculations reveal the mechanism, and further indicate the grain boundaries are inverted to n type, establishing local p-n junctions which assist electron-hole pair separation, thereby explaining the universally high collection efficiency of Cl-doped CdTe solar cells.
Abstract: When CdTe solar cells are doped with Cl, the grain boundaries no longer act as recombination centers but actively contribute to carrier collection efficiency. The physical origin of this remarkable effect has been determined through a combination of aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles theory. Cl substitutes for a large proportion of the Te atoms within a few unit cells of the grain boundaries. Density functional calculations reveal the mechanism, and further indicate the grain boundaries are inverted to n type, establishing local p-n junctions which assist electron-hole pair separation. The mechanism is electrostatic, and hence independent of the geometry of the boundary, thereby explaining the universally high collection efficiency of Cl-doped CdTe solar cells.
TL;DR: The interaction between slip bands and grain boundaries in commercial-purity titanium was examined using cross-correlation-based electron backscatter diffraction in this article, where three types of interactions were observed: blocked slip band with stress concentration, slip transfer, and no stress concentration.
TL;DR: The selective functionalization of graphene defect sites, together with the nanowire morphology of deposited Pt, yields a superior platform for sensing applications and high-performance hydrogen gas sensors at room temperature are demonstrated.
Abstract: One-dimensional defects in graphene have a strong influence on its physical properties, such as electrical charge transport and mechanical strength. With enhanced chemical reactivity, such defects may also allow us to selectively functionalize the material and systematically tune the properties of graphene. Here we demonstrate the selective deposition of metal at chemical vapour deposited graphene’s line defects, notably grain boundaries, by atomic layer deposition. Atomic layer deposition allows us to deposit Pt predominantly on graphene’s grain boundaries, folds and cracks due to the enhanced chemical reactivity of these line defects, which is directly confirmed by transmission electron microscopy imaging. The selective functionalization of graphene defect sites, together with the nanowire morphology of deposited Pt, yields a superior platform for sensing applications. Using Pt–graphene hybrid structures, we demonstrate high-performance hydrogen gas sensors at room temperature and show its advantages over other evaporative Pt deposition methods, in which Pt decorates the graphene surface non-selectively. Defects in graphene strongly influence the material's physical properties, leading to the suggestion that defects might be tuned to improve performance. Here, via atomic layer deposition, the authors selectively deposit Pt at graphene line defects and yield a superior platform for sensing applications.
TL;DR: In this article, the effect of grain size on the energy storage properties of TiO 3 (BST) ceramics with various grain sizes (0.5-5.6μm) was investigated.
Abstract: (Ba 0.4 Sr 0.6 )TiO 3 (BST) ceramics with various grain sizes (0.5–5.6 μm) were prepared by conventional solid state reaction methods. The effect of grain size on the energy storage properties of BST ceramics ( T c ≈ −65 °C) was investigated. With decreasing grain sizes, a clear tendency toward the diffuse phase transition was observed and the dielectric nonlinearity was reduced gradually, which can be explained by the Devonshire's phenomenological theory (from the viewpoint of intrinsic polarization). Based on the multi-polarization mechanism model, the relationship between the polarization behavior of polar nano-regions (the extrinsic nonlinear polarization mechanisms) and grain size was studied. The variation of the grain boundary density was thought to play an important role on the improvement of dielectric breakdown strength, account for the enhanced energy density, which was confirmed by the complex impedance spectroscopy analysis based on a double-layered dielectric model.
TL;DR: In this paper, a detailed study of deformation-induced segregation and precipitation mechanisms in an aluminum alloy containing 5.8% Mg subjected to severe plastic deformation (SPD) is presented.
TL;DR: In this article, mass-produced graphene films synthesized by hydrogen-free rapid thermal chemical vapor deposition (RT-CVD), roll-to-roll etching, and transfer methods were reported.
Abstract: The practical use of graphene in consumer electronics has not been demonstrated since the size, uniformity, and reliability problems are yet to be solved to satisfy industrial standards Here we report mass-produced graphene films synthesized by hydrogen-free rapid thermal chemical vapor deposition (RT-CVD), roll-to-roll etching, and transfer methods, which enabled faster and larger production of homogeneous graphene films over 400 × 300 mm2 area with a sheet resistance of 249 ± 17 Ω/sq without additional doping The properties of RT-CVD graphene have been carefully characterized by high-resolution transmission electron microscopy, Raman spectroscopy, chemical grain boundary analysis, and various electrical device measurements, showing excellent uniformity and stability In particular, we found no significant correlation between graphene domain sizes and electrical conductivity, unlike previous theoretical expectations for nanoscale graphene domains Finally, the actual application of the RT-CVD films to
TL;DR: In this article, an atomic-scale study was conducted to reveal the origin of the large grain-boundary (GB) resistance in Li-ion-conducting solid electrolytes and the importance of the grain boundary modification to the macroscopic Li+ conductivity.
Abstract: Li-ion-conducting solid electrolytes are the potential solution to the severe safety issues that occur with conventional batteries based on solvent-based electrolytes. The ionic conductivity of solid electrolytes is in general too low, however, due to a high grain-boundary (GB) resistance. A thorough understanding of the ionic transport mechanism at GBs in these materials is critical for a revolutionary development of next-generation Li batteries. Herein we present the first atomic-scale study to reveal the origin of the large GB resistance; (Li3xLa2/3−x)TiO3 was chosen as a prototype material to demonstrate the concept. A strikingly severe structural and chemical deviation of about 2–3 unit cells thick was revealed at the grain boundaries. Instead of preserving the ABO3 perovskite framework, such GBs were shown to consist of a binary Ti–O compound, which prohibits the abundance and transport of the charge carrier Li+. This observation has led to a potential strategy for tailoring the grain boundary structures. This study points out, for the first time, the importance of the atomic-scale grain-boundary modification to the macroscopic Li+ conductivity. Such a discovery paves the way for the search and design of solid electrolytes with superior performance.
TL;DR: In this article, the authors present and justify a concise hypothesis on the topography of the functional space of interface energies and, based on this hypothesis, construct a closed-form function that quantitatively describes energy variations in the 5-space of macroscopic parameters defining grain boundary geometry.
TL;DR: In this paper, the effect of indirect extrusion on microstructural refinement, mechanical properties and corrodibility of the pure Mg and Mg-Ca alloys in Hank's solution has been systematically studied.
TL;DR: This study presents dislocation motion, glide and climb, leading to grain boundary migration in a tungsten disulphide monolayer, and demonstrates how dislocations introduce considerable strain along the grain boundaries and at the dislocation cores.
Abstract: Dislocations have a significant effect on mechanical, electronic, magnetic and optical properties of crystals. For a dislocation to migrate in bulk crystals, collective and simultaneous movement of several atoms is needed. In two-dimensional crystals, in contrast, dislocations occur on the surface and can exhibit unique migration dynamics. Dislocation migration has recently been studied in graphene, but no studies have been reported on dislocation dynamics for two-dimensional transition metal dichalcogenides with unique metal-ligand bonding and a three-atom thickness. This study presents dislocation motion, glide and climb, leading to grain boundary migration in a tungsten disulphide monolayer. Direct atomic-scale imaging coupled with atomistic simulations reveals a strikingly low-energy barrier for glide, leading to significant grain boundary reconstruction in tungsten disulphide. The observed dynamics are unique and different from those reported for graphene. Through strain field mapping, we also demonstrate how dislocations introduce considerable strain along the grain boundaries and at the dislocation cores.
TL;DR: In this article, the effects of annealing treatment and bias filed on electrical properties were investigated for co-doped rutile TiO2 ceramics, where the electric behaviors of samples were found to be susceptible to the anneal treatment and the bias field.
Abstract: The (Nb + In) co-doped TiO2 ceramics recently attracted considerable attention due to their colossal dielectric permittivity (CP) (∼100,000) and low dielectric loss (∼0.05). In this research, the 0.5 mol. % In-only, 0.5 mol. % Nb-only, and 0.5–7 mol. % (Nb + In) co-doped TiO2 ceramics were synthesized by standard conventional solid-state reaction method. Microstructure studies showed that all samples were in pure rutile phase. The Nb and In ions were homogeneously distributed in the grain and grain boundary. Impedance spectroscopy and I-V behavior analysis demonstrated that the ceramics may compose of semiconducting grains and insulating grain boundaries. The high conductivity of grain was associated with the reduction of Ti4+ ions to Ti3+ ions, while the migration of oxygen vacancy may account for the conductivity of grain boundary. The effects of annealing treatment and bias filed on electrical properties were investigated for co-doped TiO2 ceramics, where the electric behaviors of samples were found to be susceptible to the annealing treatment and bias field. The internal-barrier-layer-capacitance mechanism was used to explain the CP phenomenon, the effect of annealing treatment and nonlinear I-V behavior for co-doped rutile TiO2 ceramics. Compared with CaCu3Ti4O12 ceramics, the high activation energy of co-doped rutile TiO2 (3.05 eV for grain boundary) was thought to be responsible for the low dielectric loss.
TL;DR: In this article, it was shown that Gd forms a solid solution within the Mg matrix in addition to substantial segregation at high-angle grain boundaries in the form of 1-2 nm clusters, with a postulated face-centered cubic Gd structure.
TL;DR: In this article, two classical models (Langmuir-McClean and Cahn-Lucke-Stuwe) are used to explore the likely effect of rare-earth (RE) additions on grain boundary solute concentration and drag.
Abstract: Magnesium alloys that contain certain rare-earth (RE) additions are known to have improved formability and this can be partly attributed to the different texture they display after recrystallization. Previous experimental work has identified segregation of RE to grain boundaries and dislocations as being potentially important in producing this change in behavior. In the present paper, two classical models (Langmuir–McClean and Cahn–Lucke–Stuwe) are used to explore the likely effect of RE additions on grain boundary solute concentration and drag. It is demonstrated that a wide range of RE elements are predicted to segregate strongly to grain boundaries due to the large atomic size misfit with magnesium. The maximum level of segregation is produced for elements such as Y or Gd that combine a high misfit and high bulk solubility. Segregated Y is predicted to produce a solute drag pressure on migrating boundaries several orders of magnitude greater than that obtained by Al or Zn additions. It is demonstrated that while this drag is predicted to be insufficient to strongly retard static recrystallization under typical annealing conditions, it is expected to suppress dynamic recrystallization by any mechanism requiring boundary migration.
TL;DR: Numerical simulations and transport measurements are used to demonstrate that electrical properties and chemical modification of graphene grain boundaries are strongly correlated, which provides guidelines for the improvement of graphene devices and opens a new research area of engineering graphenegrain boundaries for highly sensitive electro-biochemical devices.
Abstract: Graphene has attracted significant interest both for exploring fundamental science and for a wide range of technological applications. Chemical vapor deposition (CVD) is currently the only working approach to grow graphene at wafer scale, which is required for industrial applications. Unfortunately, CVD graphene is intrinsically polycrystalline, with pristine graphene grains stitched together by disordered grain boundaries, which can be either a blessing or a curse. On the one hand, grain boundaries are expected to degrade the electrical and mechanical properties of polycrystalline graphene, rendering the material undesirable for many applications. On the other hand, they exhibit an increased chemical reactivity, suggesting their potential application to sensing or as templates for synthesis of one-dimensional materials. Therefore, it is important to gain a deeper understanding of the structure and properties of graphene grain boundaries. Here, we review experimental progress on identification and electrical and chemical characterization of graphene grain boundaries. We use numerical simulations and transport measurements to demonstrate that electrical properties and chemical modification of graphene grain boundaries are strongly correlated. This not only provides guidelines for the improvement of graphene devices, but also opens a new research area of engineering graphene grain boundaries for highly sensitive electro-biochemical devices.
TL;DR: In this paper, hydrogen embrittlement of a precipitation-hardened Fe-26Mn-11Al-1.2C (wt.%) austenitic steel was examined by tensile testing under hydrogen charging and thermal desorption analysis.
TL;DR: In this paper, current developments in kinetic and thermodynamic stabilization of grains in nanostructured metals, alloys, and compounds are generalized and discussed in detail, along with experimental information about behavior of nanomaterials subjected to radiation or oxidation.
Abstract: Current developments in kinetic and thermodynamic stabilization of grains in nanostructured metals, alloys, and compounds are generalized and discussed in detail. As applied to the thermodynamic approach, attention has recently shifted from using the regular solution approximation to estimating thermodynamic properties of nanomaterials by considering both inner regions of nanograins and their grain boundaries. This situation is discussed and examples for alloys based on iron, copper, tungsten, and other elements are presented. Experimental information about behavior of nanomaterials subjected to radiation or oxidation is considered, along with recent experiments on abnormal grain growth.
TL;DR: The authors showed that the Hall-petch effect is not another size effect sui generis but is the same size effect as that observed in epitaxial thin film growth and in micromechanical testing of small specimens.