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Grain growth

About: Grain growth is a research topic. Over the lifetime, 19901 publications have been published within this topic receiving 447044 citations.


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TL;DR: In this paper, a high-entropy FeCoNiCrMn alloy with a single face-centered cubic phase was synthesized and subsequently annealed at different temperatures to systematically investigate the grain growth behavior.

598 citations

Journal ArticleDOI
TL;DR: The influence of postdeposition annealing on the structural and optical properties of rf sputtered insulating zinc oxide films has been investigated in this article, where the optical dispersion data have been fitted to (1) a single oscillator model and (2) the Pikhtin-Yas'kov model.
Abstract: The influence of postdeposition annealing on the structural and optical properties of rf sputtered insulating zinc oxide films has been investigated. The as‐grown films deposited on quartz substrates were highly c‐axis oriented and in a state of stress. These films become almost stress free after a postdeposition annealing treatment at 673 K for 1 h in air. Above 673 K, a process of coalescence was observed which causes major grain growth resulting in microcrack formation and surface roughness. The refractive index shows a strong frequency dispersion below the interband absorption edge. The optical dispersion data have been fitted to (1) a single oscillator model and (2) the Pikhtin–Yas’kov model. The origin of optical dispersion at different annealing temperatures has been discussed in the light of these models. A packing density of more than 99% is estimated in the film annealed at 673 K, indicating that these films are almost void free.

593 citations

Journal ArticleDOI
TL;DR: In this article, an atomic-scale simulation of the plastic behavior of nanocrystalline copper is presented, where the main deformation mode is sliding in the grain boundaries through a large number of uncorrelated events, where a few atoms (or tens of atoms) slide with respect to each other.
Abstract: Nanocrystalline metals, ie, metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength We present atomic-scale simulations of the plastic behavior of nanocrystalline copper The simulations show that the main deformation mode is sliding in the grain boundaries through a large number of uncorrelated events, where a few atoms (or a few tens of atoms) slide with respect to each other Little dislocation activity is seen in the grain interiors The localization of the deformation to the grain boundaries leads to a hardening as the grain size is increased (reverse Hall-Petch effect), implying a maximum in hardness for a grain size above the ones studied here We investigate the effects of varying temperature, strain rate, and porosity, and discuss the relation to recent experiments At increasing temperatures the material becomes softer in both the plastic and elastic regime Porosity in the samples result in a softening of the material; this may be a significant effect in many experiments

592 citations

Journal ArticleDOI
TL;DR: In this paper, a 2D cellular automata (CA) technique is proposed for the simulation of dendritic grain formation during solidification, which takes into account the heterogeneous nucleation, the growth kinetics and the preferential growth directions of the dendrites.
Abstract: A new algorithm based upon a 2-dimensional Cellular Automaton (CA) technique is proposed for the simulation of dendritic grain formation during solidification. The CA model takes into account the heterogeneous nucleation, the growth kinetics and the preferential growth directions of the dendrites. This new CA algorithm, which applies to non-uniform temperature situations, is fully coupled to an enthalpybased Finite Element (FE) heat flow calculation. At each time-step, the temperature at the cell locations is interpolated from those at the FE nodal points in order to calculate the nucleation-growth of grains. The latent heat released by the cells and calculated using a Scheil-type approximation is fed back into the FE nodal points. The coupled CA-FE model is applied to two solidification experiments, the Bridgman growth of an organic alloy and the one-dimensional solidification of an Al-7wt% Si alloy. In the first case, the predicted boundaries between grains are in good agreement with experiment, providing the CA cell size is of the order of the dendrite spacing. For the second experiment, the quality of the coupled CA-FE model is assessed based upon grain structures and cooling curves. The columnar-to-equiaxed transition and the occurrence of a recalescence are shown to be in good agreement with the model.

587 citations

Journal ArticleDOI
TL;DR: This paper investigated the effect of melt on the creep behavior of water-free olivine aggregates deformed in the dislocation creep regime and found that the influence of the melt phase is modest at melt fractions less than ∼ 0.04.
Abstract: Experiments have been conducted to investigate the effect of melt on the creep behavior of water-free olivine aggregates deformed in the dislocation creep regime. The influence of the melt phase is modest at melt fractions less than ∼0.04. However, at melt fractions > 0.04, the creep rate of melt-added samples is enhanced by more than an order of magnitude relative to melt-free aggregates. This unexpectedly large influence of melt on strain rate arises because deformation occurs by grain boundary sliding (GBS) accommodated by a dislocation creep process. Four observations support this hypothesis. (1) The strain rate enhancement observed in the dislocation creep regime can be related to the stress concentration caused by the reduction in the solid-solid grain boundary area. (2) Both melt-free and melt-added samples exhibit strain rates indicating that deformation is limited by slip on (010)[100], the easiest slip system in olivine. (3) The GBS mechanism occurs near the transition between diffusion and dislocation creep. (4) Grains in specimens deformed in the GBS regime are not significantly flattened, even after ∼50% shortening. In melt-free aggregates, a transition from the GBS mechanism to dislocation creep limited by slip on (010)[001], the hardest slip system, is observed with an increase in grain size. A transition to (010)[001] limited creep was not observed for partially molten aggregates because grain growth was inhibited by the presence of melt. The results of this study indicate that the viscosity of the upper mantle may decrease by at least an order of magnitude if the retained melt fraction exceeds 0.04 or if the onset of melting results in a reduction in grain size and a concomitant transition from (010)[001] to (010)[100] limited creep.

573 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023164
2022375
2021702
2020726
2019690
2018709