Metal precipitation at grain boundaries in silicon: Dependence on grain boundary character and dislocation decoration

2006 ◽  
Vol 89 (4) ◽  
pp. 042102 ◽  
Author(s):  
T. Buonassisi ◽  
A. A. Istratov ◽  
M. D. Pickett ◽  
M. A. Marcus ◽  
T. F. Ciszek ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Metal Precipitation

scholarly journals Stress Corrosion Cracks in Pipeline Steels

2019 ◽  
Author(s):  
Mohammad Ali Mohtadi Bonab
Keyword(s):  
Grain Boundary ◽  
Crack Propagation ◽  
Grain Boundaries ◽  
Stress Corrosion ◽  
Coincidence Site Lattice ◽  
Rolling Plane ◽  
Pipeline Steels ◽  
Factors Affecting ◽  
Boundary Character ◽  
Grain Boundary Character

The demand for pipeline steels has increased in the last several decades since they were able to provide an immune and economical way to carry oil and natural gas over long distances. There are two important damage modes in pipeline steels including stress corrosion cracking (SCC) and hydrogen induced cracking (HIC). The SCC cracks are those cracks which are induced due to the combined effects of a corrosive environment and sustained tensile stress. The present review article is an attempt to highlight important factors affecting the SCC in pipeline steels. Based on a literature survey, it is concluded that many factors, such as microstructure of steel, residual stresses, chemical Composition of steel, applied load, alternating current (AC) current and texture, and grain boundary character affect the SCC crack initiation and propagation in pipeline steels. It is also found that crystallographic texture plays a key role in crack propagation. Grain boundaries associated with {111}//rolling plane, {110}//rolling plane, coincidence site lattice boundaries and low angle grain boundaries are recognized as crack resistant paths while grains with high angle grain boundaries provide easy path for the SCC intergranular crack propagation. Finally, the SCC resistance in pipeline steels is improved by modifying the microstructure of steel or controlling the texture and grain boundary character.

SEM-ECP Analysis of Grain-Boundary Character Distribution in Polycrystalline Materials

1996 ◽  
Vol 54 ◽  
pp. 354-355
Author(s):  
Tadao Watanabe
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Polycrystalline Materials ◽  
Grain Boundary Character Distribution ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution

As demonstrated early 1980’s (1), the scanning electron rnicrocopy-electron channelling pattern (SEM-ECP) technique is very powerful in determination of orientation of individual grains and the character of grain boundaries in polycrystalline materials. Figure 1(a) and (b) show SEM and ECP images of a grain boundary in polycrystal line iron-6.5 mass % silicon ribbon produced by rapid solidification and subsequent annealing. We can intuitively recognize from the SEM-ECP image that the character of the boundary is of <100> tilt type with about 7° misorientation angle. This kind of direct observation is very useful for a study of grain boundary migration and grain growth.This paper discusses advantages of the SEM-ECP technique for the precise determination of the character of grain boundary and for statistical analysis of grain boundaries to bridge roles of individual grain boundaries and bulk properties in a polycrystal. The new microstructural parameter associated with grin boundary termed “grain boundary character distribution (GBCD)” which was introduced by the present author (2,3) and has been utilized in designing and engineering grain boundaries in order to produce desirable and/or high bulk performance in polycrystalline materials (4,5). GBCD describes the type and the frequency of different types of grain boundaries, ie. random general boundaries and special boundaries like low-angle boundaries and low Σ coincidence boundaries.

The Potential of HAZ Property Improvement through Control of Grain Boundary Character in a Wrought Ni-Based Superalloy

2010 ◽  
Vol 654-656 ◽  
pp. 488-491 ◽  
Author(s):  
Hyun Uk Hong ◽  
In Soo Kim ◽  
Baig Gyu Choi ◽  
Hi Won Jeong ◽  
Seong Moon Seo ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Solution Treatment ◽  
Crystallographic Analysis ◽  
Treatment Temperature ◽  
Solution Treatment Temperature ◽  
Slow Cooling ◽  
Grain Coarsening ◽  
Boundary Character ◽  
Grain Boundary Character

The effects of grain boundary serration on grain coarsening and liquation behavior in simulated weld heat-affected-zone (HAZ) of a wrought Ni-based superalloy Alloy 263 have been investigated. Recently, the present authors have found that grain boundary serration occurs in the absence of adjacent coarse γ' particles or M23C6 carbides when a specimen is direct-aged with a combination of slow cooling from solution treatment temperature to aging temperature. This serration leads to a change in grain boundary character as special boundary based on the crystallographic analysis demonstrating that the grain boundaries tend to serrate to have specific segments approaching to one {111} low-index plane at a boundary. The present study was initiated to investigate the interdependence of the serration and HAZ property with a consideration of this serration as a potential for the use of a damage-tolerant microstructure. It was found that the serrated grain boundaries suppress effectively grain coarsening, and are highly resistant to liquation cracking in HAZ due to their lower tendency to be wetted and penetrated by the liquid phase. These results reflect closely a significant decrease in interfacial energy as well as grain boundary configuration by the serration.

scholarly journals Effects of Different Parameters on Initiation and Propagation of Stress Corrosion Cracks in Pipeline Steels: A Review

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 590 ◽  
Author(s):  
M.A. Mohtadi-Bonab
Keyword(s):  
Grain Boundary ◽  
Crack Propagation ◽  
Grain Boundaries ◽  
Stress Corrosion ◽  
Coincidence Site Lattice ◽  
Rolling Plane ◽  
Pipeline Steels ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Initiation And Propagation

The demand for pipeline steels has increased in the last several decades since they were able to provide an immune and economical way to carry oil and natural gas over long distances. There are two important damage modes in pipeline steels including stress corrosion cracking (SCC) and hydrogen induced cracking (HIC). The SCC cracks are those cracks which are induced due to the combined effects of a corrosive environment and sustained tensile stress. The present review article is an attempt to highlight important factors affecting the SCC in pipeline steels. Based on a literature survey, it is concluded that many factors, such as microstructure of steel, residual stresses, chemical composition of steel, applied load, alternating current (AC) current and texture, and grain boundary character affect the SCC crack initiation and propagation in pipeline steels. It is also found that crystallographic texture plays a key role in crack propagation. Grain boundaries associated with {111}∥rolling plane, {110}∥rolling plane, coincidence site lattice boundaries and low angle grain boundaries are recognized as crack resistant paths while grains with high angle grain boundaries provide easy path for the SCC intergranular crack propagation. Finally, the SCC resistance in pipeline steels is improved by modifying the microstructure of steel or controlling the texture and grain boundary character.

Dislocation density based crystal plasticity finite element simulation of Al bicrystal with grain boundary effects

2014 ◽  
Vol 1651 ◽  
Author(s):  
Zhe Leng ◽  
David P. Field ◽  
Alankar Alankar
Keyword(s):  
Finite Element ◽  
Dislocation Density ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Crystal Plasticity ◽  
Microstructure Evolution ◽  
Polycrystalline Materials ◽  
Boundary Character ◽  
Crystal Plasticity Finite Element ◽  
Grain Boundary Character

ABSTRACTCrystal plasticity finite element method is a useful tool to investigate the anisotropic mechanical behaviors as well as the microstructure evolution of metallic materials and it is widely used on single crystals and polycrystalline materials. However, grain boundary involved mechanisms are barely included in the polycrystalline models, and modeling the interaction between the dislocation and the grain boundaries in polycrystalline materials in a physically consisstent way is still a long-standing, unsolved problem. In our analysis, a dislocation density based crystal plasticity finite element model is proposed, and the interaction between the dislocation density and the grain boundaries is included in the model kinematically. The model is then applied to Al bicrystals under 10% compression to investigate the effects of grain boundary character, e.g. grain boundary misorientation and grain boundary normal, on the stress state and the microstructure evolution. The modeling results suggest a reasonable correspondence with the experimental result and the grain boundary character plays a crucial role in the stress concentration and dislocation patterning.

Grain boundary character information via individual imaging or statistical analyses: complexion transitions and grain boundary segregation

2021 ◽  
Author(s):  
Katharina Marquardt ◽  
David Dobson ◽  
Simon Hunt ◽  
Ulrich Faul
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Bulk Viscosity ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Transmission Electron

&lt;p&gt;Grain boundaries affect bulk properties of polycrystalline materials, such as electrical conductivity, melting or bulk viscosity. In the past two decades, observations of marked bulk material property changes have been associated with changes in the structure and composition of grain boundaries. This led to the term &amp;#8220;grain boundary complexions&amp;#8221; to mark the phase-like behaviour of grain boundaries while differing from phases in the sense of Gibbs (Cantwell 2014).&lt;/p&gt;&lt;p&gt;Here we introduce the principles of grain boundary structure to property relations and potent methods to study these. The focus is on the combination of structural, chemical and statistical analysis as obtainable using transmission electron microscopy and electron backscatter diffraction. Data from these complementary methods will be discussed on two systems; garnet and olivine polycrystals.&lt;/p&gt;&lt;p&gt;Past elasticity measurements showed that the Youngs modulus of garnet polycrystals changes as a function of sintering pressure (Hunt et al. 2016). Here we used high resolution transmission electron microscopy to study the structure of grain boundaries from polycrystals synthesized at low (4-8 GPa) and high (8-15) GPa sintering pressure. The HRTEM data were acquired using an image-corrected JEOL ARM 300 to achieve the highest resolution at low electron doses using a OneView camera. Our data indicate a grain boundary structural change occurs from &amp;#8220;low-pressure&amp;#8221; to &amp;#8220;high pressure&amp;#8221; grain boundaries, where the grain boundary facets change from &gt;100 nm &amp;#8211; 20 nm to 3-7 nm length scale, respectively. We conclude that sintering pressure affects grain-boundary strength and we will evaluate how this may influence anelastic energy loss of seismic waves through elastic or diffusional accommodation of grain-boundary sliding.&lt;/p&gt;&lt;p&gt;Polycrystalline olivine samples show different viscosity related to grain boundary segregation of impurities. To investigate if the distribution of grain boundaries is affected by grain boundary chemistry, we analysed grain orientation data from over 4x10&lt;sup&gt;4&lt;/sup&gt; grains, corresponding to more than 6000 mm grain boundary length per sample. Using stereology, we extract the geometry of the interfacial network. The thus obtained grain boundary character distribution (GBCD) is discussed in relation to bulk viscosity.&lt;/p&gt;

scholarly journals Influence of Grain Boundary Character and Annealing Time on Segregation in Commercially Pure Nickel

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Shery L. Welsh ◽  
Monica Kapoor ◽  
Olivia D. Underwood ◽  
Richard L. Martens ◽  
Gregory B. Thompson ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Annealing Time ◽  
Electron Backscatter Diffraction ◽  
Atom Probe ◽  
Pure Nickel ◽  
Polycrystalline Materials ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Commercially Pure

Commercially pure nickel (Ni) was thermomechanically processed to promote an increase in Σ3 special grain boundaries. Engineering the character and chemistry of Σ3 grain boundaries in polycrystalline materials can help in improving physical, chemical, and mechanical properties leading to improved performance. Type-specific grain boundaries (special and random) were characterized using electron backscatter diffraction and the segregation behavior of elements such as Si, Al, C, O, P, Cr, Mg, Mn, B, and Fe, at the atomic level, was studied as a function of grain boundary character using atom probe tomography. These results showed that the random grain boundaries were enriched with impurities to include metal oxides, while Σ3 special grain boundaries showed little to no impurities at the grain boundaries. In addition, the influence of annealing time on the concentration of segregants on random grain boundaries was analyzed and showed clear evidence of increased concentration of segregants as annealing time was increased.

Thermal Stability of Microstructure in Grain Boundary Character Distribution-Optimized and Cold-Worked Austenitic Stainless Steel Developed for Nuclear Reactor Application

2009 ◽  
Vol 1215 ◽  
Author(s):  
Shinichiro Yamashita ◽  
Yasuhide Yano ◽  
Ryusuke Tanikawa ◽  
Norihito Sakaguchi ◽  
Seiichi Watanabe ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Boundary Character Distribution ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution ◽  
Cold Worked

AbstractGrain boundary character distribution-optimized (GBCD) Type 316 corresponding austenitic stainless steel and its cold-worked ones (GBCD+CW) are one of prospective nuclear materials to be considered for next generation energy systems. These steels were thermally-aged at 973 K for 1 and 100 h and were examined by transmission electron microscopy (TEM) to evaluate microstructural stability during high temperature exposure. TEM results revealed that microstructures of both specimens prior to ageing contained step-wise boundaries which is composed of coincidence site lattice (CSL) and random grain boundaries and also that the GBCD+CW specimens had dislocation cells and networks as well as deformation twins whereas as the GBCD one possessed few dislocations. After thermal ageing, the precipitates formed on not only random grain boundaries but also dislocations, contributing to prevent significant microstructural change occurring such as recrystallization and dislocation recovery.

scholarly journals Influence of Grain Boundary Character on Creep Void Formation in Alloy 617

2009 ◽  
Vol 40 (12) ◽  
pp. 2803-2811 ◽  
Author(s):  
Thomas Lillo ◽  
James Cole ◽  
Megan Frary ◽  
Scott Schlegel
Keyword(s):  
Grain Boundary ◽  
Void Formation ◽  
Alloy 617 ◽  
Boundary Character ◽  
Grain Boundary Character
Sign in / Sign up

Export Citation Format

Share Document