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.

Grain Growth Behaviour Of Nanocrystalline Nickel

1991 ◽  
Vol 238 ◽  
Author(s):  
A. M. El-Sherik ◽  
K. Boylan ◽  
U. Erb ◽  
G. Palumbo ◽  
K. T. Aust
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Thermal Stabilization ◽  
Growth Behaviour ◽  
In Situ Electron Microscopy ◽  
Thermal Stability Of

ABSTRACTThe thermal stability of electrodeposited nanocrystalline Ni-1.2%P and Ni-0.12%S alloys is evaluated by in-situ electron microscopy studies. Isothermal grain size versus annealing time curves at 573K and 623K show an unexpected thermal stabilization in form of a transition from rapid initial grain growth to negligible grain growth. This behaviour is discussed in terms of the various grain boundary drag mechanisms which may be operative in these alloys.

scholarly journals Improved Hardness and Thermal Stability of Nanocrystalline Nickel Electrodeposited with the Addition of Cysteine

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2254
Author(s):  
Tamás Kolonits ◽  
Zsolt Czigány ◽  
László Péter ◽  
Imre Bakonyi ◽  
Jenő Gubicza
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Dislocation Density ◽  
Nickel Sulfate ◽  
Fault Probability ◽  
Nanocrystalline Nickel ◽  
Twin Fault ◽  
Cysteine Content ◽  
Heating Up ◽  
Thermal Stability Of

Experiments were conducted for the study of the effect of cysteine addition on the microstructure of nanocrystalline Ni films electrodeposited from a nickel sulfate-based bath. Furthermore, the thermal stability of the nanostructure of Ni layers processed with cysteine addition was also investigated. It was found that with increasing cysteine content in the bath, the grain size decreased, while the dislocation density and the twin fault probability increased. Simultaneously, the hardness increased due to cysteine addition through various effects. Saturation in the microstructure and hardness was achieved at cysteine contents of 0.3–0.4 g/L. Moreover, the texture changed from (220) to (200) with increasing the concentration of cysteine. The hardness of the Ni films processed with the addition of 0.4 g/L cysteine (∼6800 MPa) was higher than the values obtained for other additives in the literature (<6000 MPa). This hardness was further enhanced to ∼8400 MPa when the Ni film was heated up to 500 K. It was revealed that the hardness remained as high as 6000 MPa even after heating up to 750 K, while for other additives, the hardness decreased below 3000 MPa at the same temperature.

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

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
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