scholarly journals Rapid eutectic growth: from rod growth to diffusionless solidification

2022 ◽  
Vol 380 (2217) ◽  
Author(s):  
Peter K. Galenko ◽  
Junfeng Xu
Keyword(s):  
Growth Models ◽  
Eutectic Growth ◽  
Supercooled Liquid ◽  
Atomic Diffusion ◽  
Theme Issue ◽  
Calculating Method ◽  
Numerous Experimental Data ◽  
Finite Growth ◽  
Eutectic Systems ◽  
Solid Phases

Numerous experimental data on the rapid solidification of eutectic systems exhibit the formation of metastable solid phases with the initial (nominal) chemical composition. This fact is explained by the suppression of eutectic decomposition due to diffusionless (chemically partitionless) solidification beginning at a high but finite growth velocity of crystals. In the present work, a model is suggested for the diffusionless growth to analyse the atomic diffusion in the rod eutectic couples growing into supercooled liquid. A simplified calculating method for the equation related to the Bessel function in the solution of the growth of rod eutectics is obtained. This method can also be used in the calculation of other rod eutectic growth models. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

scholarly journals Nutations in growing plant shoots as a morphoelastic flutter instability

2021 ◽  
Vol 379 (2201) ◽  
pp. 20200116
Author(s):  
D. Agostinelli ◽  
G. Noselli ◽  
A. DeSimone
Keyword(s):  
Growth Models ◽  
Three Dimensional ◽  
Complex Materials ◽  
Three Dimensional Model ◽  
Theme Issue ◽  
Spontaneous Oscillations ◽  
Robotic Devices ◽  
The Impact ◽  
Plant Shoots ◽  
Mathematical Design

Growing plant shoots exhibit spontaneous oscillations that Darwin observed, and termed ‘circumnutations’. Recently, they have received renewed attention for the design and optimal actuation of bioinspired robotic devices. We discuss a possible interpretation of these spontaneous oscillations as a Hopf-type bifurcation in a growing morphoelastic rod. Using a three-dimensional model and numerical simulations, we analyse the salient features of this flutter-like phenomenon (e.g. the characteristic period of the oscillations) and their dependence on the model details (in particular, the impact of choosing different growth models) finding that, overall, these features are robust with respect to changes in the details of the growth model adopted. This article is part of the theme issue ‘Topics in mathematical design of complex materials’.

scholarly journals Introduction: energy and the subsurface

2016 ◽  
Vol 374 (2078) ◽  
pp. 20150430 ◽  
Author(s):  
Ivan C. Christov ◽  
Hari S. Viswanathan
Keyword(s):  
Porous Media ◽  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Growth Models ◽  
Front Propagation ◽  
Oil And Gas Industry ◽  
Original Research ◽  
Theme Issue ◽  
Saturated Rock ◽  
Stress Dependent

This theme issue covers topics at the forefront of scientific research on energy and the subsurface, ranging from carbon dioxide (CO 2 ) sequestration to the recovery of unconventional shale oil and gas resources through hydraulic fracturing. As such, the goal of this theme issue is to have an impact on the scientific community, broadly, by providing a self-contained collection of articles contributing to and reviewing the state-of-the-art of the field. This collection of articles could be used, for example, to set the next generation of research directions, while also being useful as a self-study guide for those interested in entering the field. Review articles are included on the topics of hydraulic fracturing as a multiscale problem, numerical modelling of hydraulic fracture propagation, the role of computational sciences in the upstream oil and gas industry and chemohydrodynamic patterns in porous media. Complementing the reviews is a set of original research papers covering growth models for branched hydraulic crack systems, fluid-driven crack propagation in elastic matrices, elastic and inelastic deformation of fluid-saturated rock, reaction front propagation in fracture matrices, the effects of rock mineralogy and pore structure on stress-dependent permeability of shales, topographic viscous fingering and plume dynamics in porous media convection. This article is part of the themed issue ‘Energy and the subsurface’.

scholarly journals Recipe for ultrafast and persistent phase-change memory materials

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Keyuan Ding ◽  
Bin Chen ◽  
Yimin Chen ◽  
Junqiang Wang ◽  
Xiang Shen ◽  
...  
Keyword(s):  
Phase Change ◽  
High Performance ◽  
Phase Change Materials ◽  
Elevated Temperatures ◽  
Random Access ◽  
Supercooled Liquid ◽  
Atomic Diffusion ◽  
Working Mechanism ◽  
Ambient Temperatures ◽  
Crystallization Speed

Abstract The contradictory nature of increasing the crystallization speed while extending the amorphous stability for phase-change materials (PCMs) has long been the bottleneck in pursuing ultrafast yet persistent phase-change random-access memory. Scandium antimony telluride alloy (ScxSb2Te3) represents a feasible route to resolve this issue, as it allows a subnanosecond SET speed but years of reliable retention of the RESET state. To achieve the best device performances, the optimal composition and its underlying working mechanism need to be unraveled. Here, by tuning the doping dose of Sc, we demonstrate that Sc0.3Sb2Te3 has the fastest crystallization speed and fairly improved data nonvolatility. The simultaneous improvement in such ‘conflicting’ features stems from reconciling two dynamics factors. First, promoting heterogeneous nucleation at elevated temperatures requires a higher Sc dose to stabilize more precursors, which also helps suppress atomic diffusion near ambient temperatures to ensure a rather stable amorphous phase. Second, however, enlarging the kinetic contrast through a fragile-to-strong crossover in the supercooled liquid regime should require a moderate Sc content; otherwise, the atomic mobility for crystal growth at elevated temperatures will be considerably suppressed. Our work thus reveals the recipe by tailoring the crystallization kinetics to design superior PCMs for the development of high-performance phase-change working memory technology.

scholarly journals Atomic Diffusion in the Supercooled Liquid and Glassy States of theZr41.2Ti13.8Cu12.5Ni10Be22.5Alloy

1995 ◽  
Vol 75 (12) ◽  
pp. 2364-2367 ◽  
Author(s):  
U. Geyer ◽  
S. Schneider ◽  
W. L. Johnson ◽  
Y. Qiu ◽  
T. A. Tombrello ◽  
...  
Keyword(s):  
Supercooled Liquid ◽  
Atomic Diffusion

COLLECTIVE MOTION AND MASS EFFECT IN A SUPERCOOLED LIQUID

2001 ◽  
Vol 15 (02) ◽  
pp. 57-60 ◽  
Author(s):  
HAO-YANG LIU ◽  
WEN-BING ZHANG ◽  
XIAN-WU ZOU ◽  
ZHUN-ZHI JIN
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ternary System ◽  
Collective Motion ◽  
Mass Effect ◽  
Supercooled Liquid ◽  
Small Mass ◽  
Dynamics Simulation ◽  
Atomic Diffusion

Collective motion and mass effect of atomic diffusion have been studied by molecular dynamics simulation on a ternary system. Small mass effect has been found, which shows about ten particles take part in the collective diffusion in the supercooled liquid.

Solubility of solid phases in eutectic systems

1986 ◽  
Vol 29 (10) ◽  
pp. 808-811
Author(s):  
V. I. Psarev
Keyword(s):  
Eutectic Systems ◽  
Solid Phases

Phase Evolution in Laser Rapid Forming of Compositionally Graded Ti–Ni Alloys

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
X. Lin ◽  
T. M. Yue ◽  
H. O. Yang ◽  
W. D. Huang
Keyword(s):  
Nickel Alloy ◽  
Microstructure Evolution ◽  
Growth Models ◽  
Eutectic Growth ◽  
Phase Evolution ◽  
Compositional Gradient ◽  
Ni Alloys ◽  
Titanium Nickel ◽  
Metallurgical Study ◽  
Laser Rapid Forming

A graded binary titanium-nickel alloy with a compositional gradient, from elemental Ti to Ti–23.2 at. % Ni, has been successfully deposited using laser rapid forming. A metallurgical study of the phase evolution along the compositional gradient showed that a series of phase evolutions α→α+β→α+β+Ti2Ni→β/B2+Ti2Ni have occurred. Phase formation and microstructure evolution along the compositional gradient was analyzed by Scheil–Gulliver and eutectic growth models. In particular, the morphology of the β/B2+Ti2Ni anomalous and coupled eutectic is discussed in detail.

scholarly journals Rod eutectic growth in bulk undercooled melts

2021 ◽  
Author(s):  
Junfeng Xu ◽  
Tao Zhang ◽  
Peter Galenko
Keyword(s):  
Bessel Function ◽  
Model Calculation ◽  
Analytical Model ◽  
Growth Velocity ◽  
Growth Models ◽  
High Growth ◽  
Eutectic Growth ◽  
Lamellar Eutectic ◽  
Undercooled Melt ◽  
Undercooled Melts

This article proposes an analytical model to understand the rod-growth of eutectic in the bulk undercooled melt. Based on the previous derivations of the lamellar eutectic growth models, relaxing the assumptions of small Peclet numbers, the model is derived by considering melt kinetic and thermal undercoolings. The intent of this model is to predict the transitions in eutectic pattern for conditions of the low and high growth velocity. In addition to investigation of the transition between lamellar and rod eutectic pattern, mathematical simplifications of solving Bessel function are presented as well, which is the most important priority to model calculation.

Morphology and Orientation Relationships of Ge Precipitates in Ag-Ge Alloys

2000 ◽  
Vol 6 (S2) ◽  
pp. 1046-1047
Author(s):  
C.P. Luo ◽  
U. Dahmen
Keyword(s):  
The Other ◽  
Cubic Phase ◽  
Orientation Relationships ◽  
Limited Solid Solubility ◽  
Key Factor ◽  
Binary Eutectic ◽  
Eutectic Systems ◽  
Solid Phases ◽  
Al Matrix

Ag-Ge forms a simple binary eutectic with only two solid phases - a Ag-rich fee phase and a Ge-rich diamond-cubic phase, both with very limited solid solubility for the other element. Because both phases are cubic and there are no intermediate compounds, precipitation of Ge in an Al matrix might be expected to be crystallographically and morphologically simple. However, previous investigations of similar alloys (Al-Ge and Al-Si) have shown that precipitation in such apparently simple eutectic systems can be surprisingly complex [1,2]. For example, it was found that Ge precipitation in Al-Ge alloys depends sensitively on the availability of lattice vacancies and that at least five different orientation relationships and even more types of morphologies can form during aging after a quench. In the course of that work it was discovered that twinning is a key factor in the development of precipitate morphologies. To understand the role of twinning in precipitation this study investigates the characteristics of precipitation in Al-Ge alloys.

The shape of dendritic tips: a test of theory with computations and experiments

2021 ◽  
Vol 379 (2205) ◽  
pp. 20200326 ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Liubov V. Toropova ◽  
Ekaterina A. Titova ◽  
Andrew Kao ◽  
Gilles Demange ◽  
...  
Keyword(s):  
Experimental Data ◽  
Complex Systems ◽  
Phase Field ◽  
Shape Function ◽  
Supercooled Liquid ◽  
Detailed Comparison ◽  
Research Groups ◽  
Computational Simulations ◽  
Theme Issue ◽  
Comparison With Experimental Data

This article is devoted to the study of the tip shape of dendritic crystals grown from a supercooled liquid. The recently developed theory (Alexandrov & Galenko 2020 Phil. Trans. R. Soc. A 378 , 20190243. ( doi:10.1098/rsta.2019.0243 )), which defines the shape function of dendrites, was tested against computational simulations and experimental data. For a detailed comparison, we performed calculations using two computational methods (phase-field and enthalpy-based methods), and also made a comparison with experimental data from various research groups. As a result, it is shown that the recently found shape function describes the tip region of dendritic crystals (at the crystal vertex and some distance from it) well. This article is part of the theme issue ‘Transport phenomena in complex systems (part 1)’.

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