scholarly journals Modification of dislocation emission sources at symmetric tilt grain boundaries in Ag by Cu solute atoms

2018 ◽  
Vol 223 ◽  
pp. 243-245 ◽  
Author(s):  
Valery Borovikov ◽  
Mikhail I. Mendelev
Keyword(s):  
Grain Boundaries ◽  
Emission Sources ◽  
Dislocation Emission ◽  
Symmetric Tilt ◽  
Solute Atoms

scholarly journals Size-Dependent Solute Segregation at Symmetric Tilt Grain Boundaries in α-Fe: A Quasiparticle Approach Study

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4197
Author(s):  
Helena Zapolsky ◽  
Antoine Vaugeois ◽  
Renaud Patte ◽  
Gilles Demange
Keyword(s):  
Grain Boundaries ◽  
Hydrostatic Stress ◽  
Strain Tensor ◽  
Elastic Field ◽  
High Angle ◽  
Atomic Size ◽  
Symmetric Tilt ◽  
Wide Range ◽  
Solute Atoms ◽  
The Impact

In the present work, atomistic modeling based on the quasiparticle approach (QA) was performed to establish general trends in the segregation of solutes with different atomic size at symmetric ⟨100⟩ tilt grain boundaries (GBs) in α-Fe. Three types of solute atoms X1, X2 and X3 were considered, with atomic radii smaller (X1), similar (X2) and larger (X3) than iron atoms, respectively, corresponding to phosphorus (P), antimony (Sb) and tin (Sn). With this, we were able to evidence that segregation is dominated by atomic size and local hydrostatic stress. For low angle GBs, where the elastic field is produced by dislocation walls, X1 atoms segregate preferentially at the limit between compressed and dilated areas. Contrariwise, the positions of X2 atoms at GBs reflect the presence of tensile and compressive areal regions, corresponding to extremum values of the σXX and σYY components of the strain tensor. Regarding high angle GBs Σ5 (310) (θ = 36.95°) and Σ29 (730), it was found that all three types of solute atoms form Fe9X clusters within B structural units (SUs), albeit being deformed in the case of larger atoms (X2 and X3). In the specific case of Σ29 (730) where the GB structure can be described by a sequence of |BC.BC| SUs, it was also envisioned that the C SU can absorb up to four X1 atoms vs. one X2 or X3 atom only. Moreover, a depleted zone was observed in the vicinity of high angle GBs for X2 or X3 atoms. The significance of this research is the development of a QA methodology capable of ascertaining the atomic position of solute atoms for a wide range of GBs, as a mean to highlight the impact of the solute atoms’ size on their locations at and near GBs.

scholarly journals Study on the Evolution of the γ′ Phase and Grain Boundaries in Nickel-Based Superalloy during Interrupted Continuous Cooling

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1464
Author(s):  
Haiping Wang ◽  
Dong Liu ◽  
Jianguo Wang ◽  
Yanhui Yang ◽  
Haodong Rao ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Short Distance ◽  
Creep Property ◽  
Maximum Amplitude ◽  
Matrix Diffusion ◽  
Cooling Rates ◽  
Continuous Cooling ◽  
Nickel Based Superalloy ◽  
The Matrix ◽  
Solute Atoms

The formation of the irregular γ′ precipitates in the nickel-based superalloy Waspaloy was investigated during the continuous cooling, which is relevant to the cooling rates and interrupted temperature. The morphology of the γ′ precipitates was observed to change from a dispersed sphere to the flower-like one with the decreasing of the cooling rates. It was found that there are three modes of transportation of the solute atoms involved in relation to the γ′ precipitates: dissolution from the small γ′ precipitates to the γ matrix, diffusion to the large γ′ precipitates from the matrix, and the short distance among γ′ precipitates close to each other. Meanwhile, the slower cooling rates tend to result in the serrated grain boundaries, and the wavelength between successive peaks (λ) and the maximum amplitude (A) are larger with the decreasing of the cooling rates. The content of the low ΣCSL boundaries increases with the decreasing of the cooling rates, which is of great benefit in improving the creep property of the Waspaloy.

A Unified Theory of Grain Boundaries I. Symmetric Tilt Boundaries

1973 ◽  
pp. 423-435
Author(s):  
M. J. Marcinkowski ◽  
K. Sadananda ◽  
Wen Feng Tseng
Keyword(s):  
Grain Boundaries ◽  
Unified Theory ◽  
Symmetric Tilt ◽  
Tilt Boundaries

scholarly journals Segregation of P and S Impurities to A Σ9 Grain Boundary in Cu

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1362
Author(s):  
Cláudio M. Lousada ◽  
Pavel A. Korzhavyi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Coordination Number ◽  
High Performance ◽  
Chemical Properties ◽  
Atomic Scale ◽  
Atomic Site ◽  
Segregation Energy ◽  
Physical Chemical ◽  
Symmetric Tilt

The segregation of P and S to grain boundaries (GBs) in fcc Cu has implications in diverse physical-chemical properties of the material and this can be of particular high relevance when the material is employed in high performance applications. Here, we studied the segregation of P and S to the symmetric tilt Σ9 (22¯1¯) [110], 38.9° GB of fcc Cu. This GB is characterized by a variety of segregation sites within and near the GB plane, with considerable differences in both atomic site volume and coordination number and geometry. We found that the segregation energies of P and S vary considerably both with distance from the GB plane and sites within the GB plane. The segregation energy is significantly large at the GB plane but drops to almost zero at a distance of only ≈3.5 Å from this. Additionally, for each impurity there are considerable variations in energy (up to 0.6 eV) between segregation sites in the GB plane. These variations have origins both in differences in coordination number and atomic site volume with the effect of coordination number dominating. For sites with the same coordination number, up to a certain atomic site volume, a larger atomic site volume leads to a stronger segregation. After that limit in volume has been reached, a larger volume leads to weaker segregation. The fact that the segregation energy varies with such magnitude within the Σ9 GB plane may have implications in the accumulation of these impurities at these GBs in the material. Because of this, atomic-scale variations of concentration of P and S are expected to occur at the Σ9 GB center and in other GBs with similar features.

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