Grain growth and grain size distributions in thin germanium films

1987 ◽  
Vol 62 (6) ◽  
pp. 2492-2497 ◽  
Author(s):  
J. E. Palmer ◽  
C. V. Thompson ◽  
Henry I. Smith
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Size Distributions ◽  
Grain Size Distributions ◽  
Germanium Films

Grain Growth in Nanocrystalline Nickel

1999 ◽  
Vol 580 ◽  
Author(s):  
G.D. Hibbard ◽  
U. Erb ◽  
K.T. Aust ◽  
G. Palumbo
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Grain Growth ◽  
Size Distributions ◽  
Nanocrystalline Nickel ◽  
Scanning Calorimetry ◽  
Solute Content ◽  
Grain Size Distributions ◽  
Thermal Stability Of ◽  
Total Solute Content

AbstractIn this study, the effect of grain size distribution on the thermal stability of electrodeposited nanocrystalline nickel was investigated by pre-annealing material such that a limited amount of abnormal grain growth was introduced. This work was done in an effort to understand the previously reported, unexpected effect, of increasing thermal stability with decreasing grain size seen in some nanocrystalline systems. Pre-annealing produced a range of grain size distributions in materials with relatively unchanged crystallographic texture and total solute content. Subsequent thermal analysis of the pre-annealed samples by differential scanning calorimetry showed that the activation energy of further grain growth was unchanged from the as-deposited nanocrystalline nickel.

scholarly journals Influence of grain growth on the thermal structure of protoplanetary discs

2020 ◽  
Vol 640 ◽  
pp. A63 ◽  
Author(s):  
Sofia Savvidou ◽  
Bertram Bitsch ◽  
Michiel Lambrechts
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Growth ◽  
Thermal Structure ◽  
Size Composition ◽  
Size Distributions ◽  
Migration Rates ◽  
Grain Size Distributions ◽  
Hydrodynamical Simulations ◽  
Protoplanetary Discs

The thermal structure of a protoplanetary disc is regulated by the opacity that dust grains provide. However, previous works have often considered simplified prescriptions for the dust opacity in hydrodynamical disc simulations, for example, by considering only a single particle size. In the present work, we perform 2D hydrodynamical simulations of protoplanetary discs where the opacity is self-consistently calculated for the dust population, taking into account the particle size, composition, and abundance. We first compared simulations utilizing single grain sizes to two different multi-grain size distributions at different levels of turbulence strengths, parameterized through the α-viscosity, and different gas surface densities. Assuming a single dust size leads to inaccurate calculations of the thermal structure of discs, because the grain size dominating the opacity increases with orbital radius. Overall the two grain size distributions, one limited by fragmentation only and the other determined from a more complete fragmentation-coagulation equilibrium, give comparable results for the thermal structure. We find that both grain size distributions give less steep opacity gradients that result in less steep aspect ratio gradients, in comparison to discs with only micrometer-sized dust. Moreover, in the discs with a grain size distribution, the innermost (<5 AU) outward migration region is removed and planets embedded in such discs experience lower migration rates. We also investigated the dependency of the water iceline position on the alpha-viscosity (α), the initial gas surface density (Σg,0) at 1 AU and the dust-to-gas ratio (fDG) and find rice ∝ α0.61Σg,00.8fDG0.37 independently of the distribution used in the disc. The inclusion of the feedback loop between grain growth, opacities, and disc thermodynamics allows for more self-consistent simulations of accretion discs and planet formation.

Temporal Evolution of Grain Size Distributions in Two-Dimensional Pinned Cells

2004 ◽  
Vol 467-470 ◽  
pp. 1003-1008
Author(s):  
C.H. Wörner ◽  
A. Olguín
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Experimental Approach ◽  
Temporal Evolution ◽  
Size Distributions ◽  
Two Dimensional ◽  
Pinning Centers ◽  
Grain Size Distributions ◽  
Polycrystalline Aggregates

The distribution of sizes for grain growth in presence of pinning centers (Zener pinned growth) is communicated at different times. The experimental approach uses the well-known similitude between growth in polycrystalline aggregates and cellular soap froths. Two-dimensional results are communicated with grain growth limited by a set of randomly distributed rounded pins.

Anomalous grain-size distributions during continuous grain growth

1983 ◽  
Vol 17 (8) ◽  
pp. 975-978 ◽  
Author(s):  
J.S. Distl ◽  
P.I. Welch ◽  
H.J. Bunge
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Size Distributions ◽  
Grain Size Distributions

Study of the Effect of Pinning Particles on Grain Size Distributions

2013 ◽  
Vol 753 ◽  
pp. 361-366 ◽  
Author(s):  
Han Li ◽  
Suk Bin Lee ◽  
Anthony D. Rollett
Keyword(s):  
Grain Size ◽  
Normal Distribution ◽  
Grain Growth ◽  
Volume Fraction ◽  
Medium Size ◽  
Second Phase ◽  
Size Distributions ◽  
Grain Size Distributions ◽  
Log Normal ◽  
Log Normal Distribution

The present paper studies grain growth in the presence of inert particles by performing large-scale simulations using a parallel Monte Carlo Potts model. The effect of the second phase particles on the grain size distribution (GSD) is analyzed. The GSDs diverge markedly from log-normal distribution for normal grain growth case. For the cases with low volume fraction of particles, we find that the grain size distributions approach log-normal as stagnation takes hold. For the cases with a high volume fraction of particles, however, medium-size grains reach the log-normal distribution but both lower and upper tails diverge noticeably from the log-normal distribution over time.

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