scholarly journals A brief overview on grain growth of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys

2019 ◽  
Vol 58 (1) ◽  
pp. 98-106
Author(s):  
Haitao Ni ◽  
Jiang Zhu ◽  
Zhaodong Wang ◽  
Haiyang Lv ◽  
Yongyao Su ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Growth Process ◽  
Boundary Migration ◽  
Thermal Conditions ◽  
Iron Alloys ◽  
Nanocrystalline Nickel ◽  
Nickel Iron ◽  
Average Grain Size

Abstract This review focuses on grain growth behaviors and the underlying mechanisms of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys. Effects of some important factors on grain growth are described. During thermal-induced grain growth process, grain boundary migration plays a key role. For similar thermal conditions, due to grain boundary mobility with solute drag, limited grain growth occurs in nanocrystalline alloys, as compared to pure metals. Nonetheless, in the case of stress-induced grain growth process, there are a variety of mechanisms in samples having various deformation histories. As an example the grain growth of nanocrystalline nickel and Ni-20%Fe alloy with nearly the same grain-size distribution and average grain size is compared in this paper. Thermal analysis indicates nanocrystalline nickel is much more prone to rapid grain growth than nanocrystalline Ni-20%Fe alloy. Nevertheless, grain growth of nanocrystalline Ni-20%Fe is found to be more pronounced than nanocrystalline nickel during rolling deformation.

scholarly journals Dome Concordia ice microstructure: impurities effect on grain growth

2002 ◽  
Vol 35 ◽  
pp. 552-558 ◽  
Author(s):  
Jérôme Weiss ◽  
Jérôme Vidot ◽  
Michel Gay ◽  
Laurent Arnaud ◽  
Paul Duval ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Growth Process ◽  
Boundary Energy ◽  
Ice Core ◽  
Dust Particles ◽  
The Holocene ◽  
Average Grain Size

AbstractWe present a detailed analysis of the microstructure in the shallow part (100–580m) of the European Project for Ice Coring in Antarctica (EPICA) ice core at Dome Concordia. In the Holocene ice, the average grain-size increases with depth. This is the normal grain-growth process driven by a reduction of the total grain-boundary energy. Deeper, associated with the Holocene–Last Glacial Maximum (LGM) climatic transition, a sharp decrease of the average grain-size is observed. to explain modifications to the microstructure with climatic change, we discuss the role of soluble and insoluble (microparticles) impurities in the grain-growth process of Antarctic ice, coupled with an analysis of the pinning of grain boundaries by microparticles. Our data indicate that high soluble impurity content does not necessarily imply a slowing-down of grain-growth kinetics, whereas the pinning of grain boundaries by dust particles located along the boundaries does explain modifications to the microstructure (small grain-sizes; change in grain-size distributions, etc.) observed in volcanic ash layers or dusty LGM ice.Moreover, classical mean-field models of grain-boundary pinning are in good quantitative agreement with the evolution of grain-size along the EPICA ice core. This suggests a major role for dust in the modification of shallow polar ice microstructure.

scholarly journals Competition between grain growth and grain-size reduction in polar ice

2011 ◽  
Vol 57 (205) ◽  
pp. 942-948 ◽  
Author(s):  
Jens Roessiger ◽  
Paul D. Bons ◽  
Albert Griera ◽  
Mark W. Jessell ◽  
Lynn Evans ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Migration ◽  
Boundary Energy ◽  
Ice Core ◽  
Size Reduction ◽  
Polar Ice ◽  
Average Grain Size ◽  
Log Normal

AbstractStatic (or ‘normal’) grain growth, i.e. grain boundary migration driven solely by grain boundary energy, is considered to be an important process in polar ice. Many ice-core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets, while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain-size reduction by dynamic recrystallization. The growth factorkin the normal grain growth law is important for any process where grain growth plays a role, and it is normally assumed to be a temperature-dependent material property. Here we show, using numerical simulations with the program Elle, that the factorkalso incorporates the effect of the microstructure on grain growth. For example, a change in grain-size distribution from normal to log-normal in a thin section is found to correspond to an increase inkby a factor of 3.5.

Grain Growth Microstructures as Indicators of Sample Evolution

2004 ◽  
Vol 467-470 ◽  
pp. 1051-1056 ◽  
Author(s):  
M.W. Jessell
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Growth Process ◽  
Grain Shape ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Microstructure Simulation ◽  
Boundary Chemistry ◽  
Grain Size And Orientation

Grain growth simulations using the microstructure simulation system Elle have been performed in materials with a pre-existing grain shape preferred orientation. As might be expected, the microstructure is completely modified by the end of the experiment, and grain areas have increased by a factor of seven. The area of material swept by the migrating grain boundaries was monitored, and it was found that at every stage, virtually all of the grains which survived the grain growth process contain one and only one core of unswept material. Remarkably these remnant unswept cores preserve a useable record of the grain size and orientation of the original grains. This work suggests that it may be possible to see past a grain growth episode to estimate the original grain shape and grain size of the polycrystal, and perhaps even reconstruct the grain boundary kinematics. The identification of unswept cores also has the potential to help unravel the evolution of grain boundary chemistry during grain boundary migration.

Effect of Grain Boundary Energy in Recrystallization Simulation by Phase Field Method

2020 ◽  
Vol 993 ◽  
pp. 953-958
Author(s):  
Yan Wu ◽  
Ren Chuang Yan ◽  
Er Wei Qin ◽  
Wei Dong Chen
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Phase Field ◽  
Boundary Energy ◽  
Phase Field Model ◽  
Field Method ◽  
Phase Field Method ◽  
Grain Boundary Energy ◽  
Average Grain Size

In this paper, the effect of grain boundary energy in AZ31 Mg alloy with multi-order parameters phenomenological phase field model has been discussed during the progress of recrystallization. The average grain size of the recrystallization grain at a certain temperature and a certain restored energy but various grain boundary energies have been studied, and the simulated results show that the larger the grain boundary energy is, the larger the average grain size will be, and the speed of grain growth will increase with the increase of grain boundary energy. Additionally, temperature will also increase the grain growth rate.

The Effects of Annealing on the Grain Growth and Surface Rearrangement of Electroplated Nickel-Iron Films

1972 ◽  
Vol 30 ◽  
pp. 514-515
Author(s):  
Y. T. Chen
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Grain Growth ◽  
Crystallographic Orientation ◽  
Annealing Treatment ◽  
Plastic Substrate ◽  
Iron Films ◽  
Surface Change ◽  
Nickel Iron ◽  
Average Grain Size

Nickel-iron films were deposited on a copper-covered plastic substrate and annealed at 400, 600, 800, 1100, and 1200°C. The films were stripped from the substrate, and were thoroughly cleaned and dried before being annealed. Recent works [1, 2] have shown that the magnetic properties of Ni-Fe films are strongly dependent on grain size, and hence on the annealing treatment. The present work emphasizes the surface change of the film due to annealing.The composition of the electroplated films was kept at 80% Ni, 20% Fe; the thicknesses of the annealed samples were from 5 to 10 μ. The structure of as-plated Ni-Fe film was found to be the disordered γ phase, which is fcc. All of the films were polycrystalline with no preferred crystallographic orientation. The average grain size of the as-plated films was 300 A (Fig. 1). This did not vary much within the prescribed thickness range.

scholarly journals Influence of Boundary Migration Induced Softening on the Steady State of Discontinuous Dynamic Recrystallization

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3531
Author(s):  
Frank Montheillet
Keyword(s):  
Grain Size ◽  
Steady State ◽  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Strain Hardening ◽  
Dynamic Recovery ◽  
Boundary Migration ◽  
Rate Sensitivity ◽  
Steady State Condition ◽  
Average Grain Size

During discontinuous dynamic recrystallization (DDRX), new dislocation-free grains progressively replace the initially strain-hardened grains. Furthermore, the grain boundary migration associated with dislocation elimination partially opposes strain hardening, thus adding up to dynamic recovery. This effect, referred to as boundary migration induced softening (BMIS) is generally not accounted for by DDRX models, in particular by “mean-field” approaches. In this paper, BMIS is first defined and then analyzed in detail. The basic equations of a grain scale DDRX model, involving the classical Yoshie–Laasraoui–Jonas equation for strain hardening and dynamic recovery and including BMIS are described. A steady state condition equation is then used to derive the average dislocation density and the average grain size. It is then possible to assess the respective influences of BMIS and dynamic recovery on the strain rate sensitivity, the apparent activation energy, and the relationship between flow stress and average grain size (“Derby exponent”) of the material during steady state DDRX. Finally, the possible influence of BMIS on the estimation of grain boundary mobility and nucleation rate from experimental data is addressed.

The effect of excess neodymia on the grain growth of Nd1+xBa2−xCu3Oy solid solutions

1998 ◽  
Vol 13 (10) ◽  
pp. 2819-2832 ◽  
Author(s):  
Russell B. Rogenski ◽  
Kenneth H. Sandhage ◽  
Alexander L. Vasiliev ◽  
Eric P. Kvam
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Grain Boundary Energy ◽  
Detectable Change ◽  
Fine Grained ◽  
Average Grain Size ◽  
Second Phases

The grain growth of dense, fine-grained Nd1+xBa2−xCu3Oy (x = 0.1−0.4) specimens has been examined in pure O2(g) at 938 °C and 967 °C. No detectable change in average grain size was observed for Nd1.4Ba1.6Cu3Oy within 72 h at 967 °C; however, a significant increase in average grain size developed between 18 and 24 h at 967 °C for Nd1.3Ba1.7Cu3Oy, and within 8−12 h at ≤967 °C for Nd1.2Ba1.8Cu3Oy and Nd1.1Ba1.9Cu3Oy. Microstructural analyses revealed that sudden changes in average grain size coincided with the formation of relatively large (abnormal) grains. A broadening of the grain size distribution was also observed. TEM analyses revealed that grain boundaries were free of second phases. The possible role of anisotropy in grain boundary energy and/or mobility on grain growth is discussed.

scholarly journals In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1862 ◽  
Author(s):  
Rongchuang Chen ◽  
Zhizhen Zheng ◽  
Jianjun Li ◽  
Ning Li ◽  
Fei Feng
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Isothermal Holding ◽  
In Situ Observation ◽  
Initial Stage ◽  
300M Steel ◽  
Average Grain Size ◽  
In Situ Observations

The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat treatment. In this work, in situ observations were carried out to characterize the grain evolutions of 300M steel with varying holding time, holding temperatures, and initial microstructures. The intriguing finding was that the grain refinement by austenization of 300M steel was followed by a dramatic grain growth in the initial stage of holding (≤~600 s), and with increasing time (~600–7200 s), the average grain size appeared to have a limit value at specific temperatures. The austenization process accelerated the grain growth by generating large quantity of grain boundaries at the initial stage of holdings, and the growth rate gradually slowed down after holding for ~600 s because the driven force was weakened due to the reduction of grain boundary energy. The initial structure and the initial grain size of 300M steel had no obvious influences on the grain size evolutions. The mechanisms of grain growth were analyzed based on in situ observations and transmission electron microscope (TEM) characterizations. A grain evolution model considering the grain boundary migration of 300M steel was established for the isothermal holding process. Good agreement was obtained between the in situ observation results and the model calculation results. This investigation aimed to understand fundamentally the grain evolutions of 300M steel in the isothermal holding process.

scholarly journals The Effect of Digm and Irradiation-Induced Grain Growth on Interdiffusion in Bilayer Ion-Beam Mixing Experiments

1992 ◽  
Vol 279 ◽  
Author(s):  
Dale E. Alexander ◽  
L. E. Rehn ◽  
Peter M. Baldo ◽  
Y. Gao
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Treatment Time ◽  
Ion Irradiation ◽  
Boundary Migration ◽  
Ion Beam ◽  
Grain Boundary Migration ◽  
Ion Beam Mixing ◽  
Boundary Velocity

ABSTRACTExperiments were performed demonstrating that ion irradiation enhances diffusion-induced grain boundary migration (DIGM) in polycrystalline Au/Cu bilayers. Here, a model is presented relating film-averaged Cu composition in Au with treatment time, grain size and film thickness. Application of this model to the experimental results indicates that irradiation enhances DIGM by increasing the grain boundary velocity. The effects of DIGM and irradiation-induced grain growth on the temperature dependence of ion mixing in bilayers are discussed.

Sign in / Sign up

Export Citation Format

Share Document