Microstructural Development of Electrical Steels under Si and Al Diffusion

2006 ◽  
Vol 258-260 ◽  
pp. 39-45
Author(s):  
José Barros ◽  
Yvan Houbaert
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Grain Growth ◽  
Alpha Phase ◽  
Microstructural Development ◽  
Diffusion Annealing ◽  
Electrical Steels ◽  
Common Features ◽  
Columnar Grain ◽  
Size And Morphology

The effect of Si and Al diffusion from a coating in the microstructure of electrical steels have been investigated for three different processing routes. In general the final texture is not affected by the diffusion of Si or Al from the coating whereas the grain size and mor- phology can be affected if the silicon content of the substrate is low enough to allow phase transformation. The gamma to alpha phase transformation caused by the diffusion of Si and Al determines the grain size and morphology resulting in columnar grain growth. The evolu- tion of the microstructures during the diffusion annealing for the production of high Si steels shows some common features with the microstructure evolution during the grain growth in conventional low silicon (Si < 3 wt.%) electrical steels.

Microstructural Design and Control of Silicon Nitride Ceramics

MRS Bulletin ◽  
1995 ◽  
Vol 20 (2) ◽  
pp. 38-41 ◽  
Author(s):  
Mamoru Mitomo ◽  
Naoto Hirosaki ◽  
Hideki Hirotsuru
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Grain Growth ◽  
Processing Parameters ◽  
Microstructural Development ◽  
Nitride Ceramics ◽  
Microstructural Design ◽  
And Control

The improvement of mechanical properties by microstructural control has been one of the main topics of interest in the development of silicon nitride ceramics. Toughening, by developing an in situ composite or self-reinforced microstructure, has attracted particular attention.Microstructural design is a key factor in the optimization of processing parameters. The microstructures of sintered materials are composed of silicon nitride grains and grain boundaries, which can be either crystalline, amorphous, or partially crystalline, depending on the composition, amount of sintering additives, and processing parameters. Silicon nitride ceramics have been fabricated with an addition of metal oxides and rare-earth oxides that form a liquid phase during sintering and accelerate grain boundary diffusion. The effect of composition of the glassy phase on the mechanical properties of ceramics is presented by Becher et al. and Hoffmann elsewhere in this issue. This article focuses specifically on the design and control of grain size.As it is well recognized, many processing parameters affect grain growth behavior and the resulting microstructure. During sintering, the α- to β-phase transformation leads to a self-reinforcing microstructure on account of the anisotropic grain growth of the stable hexagonal β- Si3N4 phase. Therefore, α-rich powders are widely used for starting materials. Phase transformation accelerates anisotropic grain growth, resulting in an increase in the fracture toughness of Si3N4 ceramics. Kang and Han discuss the effect of phase transformation on nucleation and grain growth in an article in this issue. The effect of the grain-size distribution on microstructural development is described in this article, based on studies conducted mostly with β-Si3N4 powders.

A Study on The Phase Transformation and Exchange-Coupling of (Nd0 95La0 05)9 5FebalCo5Nb2B10.5 Nanocomposites

1999 ◽  
Vol 577 ◽  
Author(s):  
Q. Chen ◽  
B. M. Ma ◽  
B. Lu ◽  
M. Q. Huang ◽  
D. E. Laughlin
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Phase Transformation ◽  
Thermal Treatment ◽  
Grain Growth ◽  
Exchange Coupling ◽  
Phase Distribution ◽  
Maximum Energy ◽  
Treatment Temperature ◽  
Phase Identification

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.

Effect of Isothermal Sintering Time on the Properties of the Ceramic Composite ZrO2-Al2O3

2006 ◽  
Vol 530-531 ◽  
pp. 526-531 ◽  
Author(s):  
Claudinei dos Santos ◽  
L.H.P. Teixeira ◽  
J.K.M.F. Daguano ◽  
Kurt Strecker ◽  
Carlos Nelson Elias
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Ceramic Composite ◽  
Growth Exponent ◽  
Microstructural Development ◽  
Growth Equation ◽  
Sintering Time ◽  
Al2o3 Composite ◽  
Average Grain Size ◽  
Grain Size Distributions

In this work the influence of isothermal sintering time on the microstructural development of ZrO2-Al2O3 composite was studied. Powder mixture of ZrO2 containing 20 wt% Al2O3 was prepared by milling, compaction and sintering at 16000C, in air. The isothermal sintering time at 16000C was varied between 0 and 1440 min. The sintered samples were characterized in terms of phase composition and relative density. Their microstructures were characterized by grain size distributions and average grain size. These results were evaluated using the classic grain growth equation as a function of time, determining the grain growth exponent of these materials. Furthermore, the microstructural aspects were related to the mechanical properties (Vicker’s hardness and fracture toughness) of these composites.

Columnar grain growth during annealing prior to cold rolling of non-oriented electrical steels

2019 ◽  
Vol 243 ◽  
pp. 8-18 ◽  
Author(s):  
E.J. Gutiérrez Castañeda ◽  
C.N. Palafox Cantú ◽  
A.A. Torres Castillo ◽  
A. Salinas Rodríguez ◽  
R. Deaquino Lara ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Grain Growth ◽  
Electrical Steels ◽  
Columnar Grain

The Potential of Combined In-Situ Heating Experiments and Detailed EBSD Analysis in the Investigation of Grain Scale Processes such as Recrystallization and Phase Transformation

2004 ◽  
Vol 467-470 ◽  
pp. 1407-1412 ◽  
Author(s):  
Sandra Piazolo ◽  
Gareth G.E. Seward ◽  
Nick Seaton ◽  
David J. Prior
Keyword(s):  
Phase Transformation ◽  
Grain Growth ◽  
Microstructural Evolution ◽  
Secondary Recrystallization ◽  
Microstructural Development ◽  
Geological Materials ◽  
Scientific Potential ◽  
In Situ Heating ◽  
Similarities And Differences

Experiments in which the microstructural development can be observed at the same time as the crystallography is described fully opens up new, powerful ways to advance our understanding of microstructural processes such as grain growth, primary and secondary recrystallization and phase transformations. In addition, comparison of results of experiments in different materials can be used to develop general laws for the investigated processes. In this study, we briefly review and compare the results from various ongoing studies undertaken in a variety of materials with emphasis on highlighting (a) the scientific potential of such experiments and (b)similarities and differences in their microstructural evolution. Materials studied include metals e.g. Ti, Ni, Al, Mg, Ti-SULC steel and geological materials such as rocksalt (NaCl), hematite and magnetite. Here, we present experimental results and their interpretation in terms of subgrain to grain-scale processes.

Recrystallisation, Grain Growth and Texture Evolution in Nonoriented Electrical Steels

2007 ◽  
Vol 558-559 ◽  
pp. 657-664 ◽  
Author(s):  
Jong Tae Park ◽  
Jae Kwan Kim ◽  
Jerzy A. Szpunar
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Grain Growth ◽  
Texture Evolution ◽  
Size Control ◽  
Goss Texture ◽  
Final Annealing ◽  
Electrical Steels ◽  
Grain Size Control ◽  
Specific Orientation

The magnetic properties of nonoriented electrical steels are influenced by grain size and texture of final products. The key technology in the commercial production of nonoriented electrical steels is to grow grains with {hk0}<001> texture up to the optimum size in the final annealing process. The problems related to grain size control have been extensively investigated, while texture control has received much less attention. Therefore, there is enough room to improve the magnetic properties through the control of texture. In this study, systematic investigations on the texture evolution during both recrystallization and grain growth have been made. The formation of recrystallization texture is explained by oriented nucleation. This is supported by the fact that the area fraction of nuclei or recrystallized grains with specific orientation to all new grains remains almost constant during the progress of recrystallization. Most nuclei have a high misorientation angle of 25∼55° with the surrounding deformed matrices. During the progress of grain growth, the Goss texture component continues to decrease because the Goss grains have a high percentage of low angle, low mobility grain boundaries. The grains of Goss orientation have a smaller grain size than those of random orientation.

scholarly journals Effect of Content and Size of Reinforcements on the Grain Evolution of Graphene-Reinforced Aluminum Matrix Composites

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2550
Author(s):  
Qi Wu ◽  
Pengfei Cai ◽  
Lianchun Long
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
High Performance ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Pinning Effect ◽  
High Temperature Processes ◽  
Average Grain Size ◽  
Size And Morphology

Graphene-reinforced aluminum matrix composites (GRAMCs) attract great interest in industries due to their high performance potential. High-temperature processes such as sintering and aging are usually applied during the preparation of GRAMCs, leading to grain coarsening that significantly influences its properties. In this work, a modified 3D Monte Carlo Potts model was proposed to investigate the effect of content and size of graphene on the grain evolution during the heat treatment of GRAMCs. Grain growth with graphene contents from 0.5 wt.% to 4.5 wt.% and sizes from 5 μm to 15 μm were simulated. The grain growth process, final grain size and morphology of the microstructure were predicted. The results indicated that both the content and size of the reinforcements had an impact on the grain evolution. The pinning effect of grain size can be enhanced by increasing the content and decreasing the size of graphene. Agglomeration and self-contacting phenomena of the graphene arose obviously when the contents and sizes were relatively high. The average grain size decreased by 48.77% when the content increased from 0.5 wt.% to 4.5 wt.%. The proposed method and predicted regulations can provide a reference for the design and fabrication of GRAMCs.

Texture Development during Final Annealing in Nonoriented Electrical Steels

2005 ◽  
Vol 495-497 ◽  
pp. 471-476 ◽  
Author(s):  
Jong Tae Park ◽  
Jerzy A. Szpunar ◽  
Jae Kwan Kim
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Grain Growth ◽  
Recrystallization Texture ◽  
Core Loss ◽  
Size Control ◽  
Final Annealing ◽  
Electrical Steels ◽  
Texture Change ◽  
Grain Size Control

Nonoriented electrical steels have been widely used as core materials in motors and generators. For these applications low core loss and high permeability are required. The magnetic properties of these steels depend on the grain size and crystallographic texture of the annealed final products. The problems related to grain size control have been extensively investigated, while texture control has received much less attention. The technologies used to control the grain size in nonoriented electrical steels have approached to their limits. However, there is still some possibility for improvement of the magnetic properties through texture control. In order to explore this possibility, the evolution of recrystallization texture for nonoriented electrical steels with 2% Si was systematically studied. Texture change during grain growth was additionally analyzed. The formation of recrystallization texture is explained by oriented nucleation. This is supported by the fact that the area fraction of nuclei or recrystallized grains with specific orientation to all new grains remains almost constant during the progress of recrystallization. Most nuclei have a high misorientation angle of 25~55° with the surrounding deformed matrices. During the progress of grain growth, Goss and {111}<112> components are weakened and the random texture is strengthened. The grains of the Goss and {111}<112> orientations have smaller grain size than those of random orientation.

An EBSD investigation on the columnar grain growth in non-oriented electrical steels assisted by strain induced boundary migration

2019 ◽  
Vol 252 ◽  
pp. 42-46 ◽  
Author(s):  
E.J. Gutiérrez Castañeda ◽  
M.G. Hernández Miranda ◽  
A. Salinas Rodríguez ◽  
J. Aguilar Carrillo ◽  
I. Reyes Domínguez
Keyword(s):  
Grain Growth ◽  
Boundary Migration ◽  
Electrical Steels ◽  
Columnar Grain
Sign in / Sign up

Export Citation Format

Share Document