scholarly journals Adatom-induced dislocation annihilation in epitaxial silicene

2D Materials ◽  
2021 ◽  
Author(s):  
Antoine Fleurence ◽  
Yukiko Yamada-Takamura
1982 ◽  
Vol 5 (3) ◽  
pp. 127-152 ◽  
Author(s):  
G. H. Edward ◽  
M. A. Etheridge ◽  
B. E. Hobbs

A simple model of the dynamic balance between deformation induced dislocation generation and climb controlled dislocation annihilation in subgrain walls is outlined. This results in a stress-subgrain size relationship which involves various material properties, including the creep stress exponent and the creep diffusivity.Assuming a fixed slip distance for mobile dislocations, the theory predicts that the subgrain size (d) depends on the stress (σ) as d4∝σ−n, where n is the creep exponent, and the proportionality constant is dependent on material properties, temperature, and other environmental variables. This theoretical prediction is satisfactorily compared with published experimental results for a variety of materials.The implications of the environmental dependence of the stress-subgrain size relation with regard to its use as a palaeopiezometer in naturally deformed minerals are discussed.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3606
Author(s):  
Tomoya Nagira ◽  
Xiaochao Liu ◽  
Kohasaku Ushioda ◽  
Hidetoshi Fujii

The grain refinement mechanisms along the material flow path in pure and high-purity Al were examined, using the marker insert and tool stop action methods, during the rapid cooling friction stir welding using liquid CO2. In pure Al subjected to a low welding temperature of 0.56Tm (Tm: melting point), the resultant microstructure consisted of a mixture of equiaxed and elongated grains, including the subgrains. Discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization are the potential mechanisms of grain refinement. Increasing the welding temperature and Al purity encouraged dynamic recovery, including dislocation annihilation and rearrangement into subgrains, leading to the acceleration of CDRX and inhibition of DDRX. Both C- and B/-type shear textures were developed in microstructures consisting of equiaxed and elongated grains. In addition, DDRX via high-angle boundary bulging resulted in the development of the 45° rotated cube texture. The B/ shear texture was strengthened for the fine microstructure, where equiaxed recrystallized grains were fully developed through CDRX. In these cases, the texture is closely related to grain structure development.


2020 ◽  
Vol 4 (7) ◽  
Author(s):  
Jie Zhang ◽  
Xuelin Yang ◽  
Yuxia Feng ◽  
Yue Li ◽  
Maojun Wang ◽  
...  

Materialia ◽  
2021 ◽  
pp. 101042
Author(s):  
S.R. Das ◽  
S. Shyamal ◽  
T. Sahu ◽  
J.I. Kömi ◽  
P.C. Chakraborti ◽  
...  

2011 ◽  
Vol 702-703 ◽  
pp. 435-438
Author(s):  
Peter D. Hodgson ◽  
Pavel Cizek ◽  
A.S. Taylor ◽  
Hossein Beladi

The current work has investigated the texture development in an austenitic Ni-30Fe model alloy during deformation within the dynamic recrystallization (DRX) regime and after post-deformation annealing. Both the deformed matrix and DRX texture displayed the expected FCC shear components, the latter being dominated by the low Taylor factor grains, which was presumably caused by their lower consumption rate during DRX. The deformed matrix grains were largely characterized by organized, microband structures, while the DRX grains showed more random, complex subgrains/cell arrangements. The latter substructure type proved to be significantly less stable during post-deformation annealing. The recrystallization of the deformed matrix occurred through nucleation and growth of new grains fully replacing the deformed structure, as expected for the classical static recrystallization (SRX). Unlike the DRX grains, the SRX texture was essentially random. By contrast, a novel softening mechanism was revealed during annealing of the fully DRX microstructure. The initial post-dynamic softening stage involved rapid growth of the dynamically formed nuclei and migration of the mobile boundaries in line with the well-established metadynamic recrystallization (MDRX) mechanism, which weakened the starting DRX texture. However, in parallel, the sub-boundaries within the deformed DRX grains progressively disintegrated through dislocation climb and dislocation annihilation, which ultimately led to the formation of dislocation-free grains. Consequently, the weakened DRX texture largely remained preserved throughout the annealing process.


2002 ◽  
Vol 17 (7) ◽  
pp. 1863-1870 ◽  
Author(s):  
Richard P. Vinci ◽  
Stefanie A. Forrest ◽  
John C. Bravman

Wafer curvature was used to study the thermal–mechanical behavior of 1-μm Cu thin films capped with a 100-nm-thick Si3N4 layer. These films were grown with either a Ta or a Si3N4 underlayer. Films on Si3N4 that were exposed to oxygen at the film/capping layer interface or at the center of the copper layer exhibited Bauschinger-like yielding at low stress. Stacks deposited under continuous vacuum, with a Ta underlayer, with carbon exposure at the upper surface of the copper film, or with oxygen exposure of only the underlayer did not demonstrate the anomalous yielding. Preferential diffusion of oxygen into copper grain boundaries or interfaces is the likely cause of the early yield behavior. Possible mechanisms include an increase in interface adhesion due to the presence of oxygen in solution and diffusion-induced dislocation glide as an additional driving force for dislocation motion at low applied stress.


2012 ◽  
Vol 706-709 ◽  
pp. 2134-2139
Author(s):  
Peter D. Hodgson ◽  
Pavel Cizek ◽  
Hossein Beladi ◽  
A.S. Taylor

The current work investigates the microstructure evolution and softening processes that take place during annealing of an austenitic Ni-30Fe model alloy subjected to hot deformation in the dynamic recrystallization (DRX) regime. The substructure of the deformed matrix grains largely comprised organized microband arrays, though that of the DRX grains consisted of more random, complex subgrain/cell arrangements. This substructure disparity was also reflected by the distinct difference in the mechanism of post-deformation softening taking place during annealing of the deformed matrix and DRX grains. In the former, the recrystallization process took place through nucleation and growth of new grains fully replacing the deformed structure, as expected for the classical static recrystallization (SRX). The corresponding texture was essentially random, in contrast to that of the DRX grains dominated by low Taylor factor components. The microbands originally present within the deformed matrix grains displayed some tendency to disintegrate during annealing, nonetheless, they remained largely preserved even at prolonged holding times. During annealing of the fully DRX microstructure, a novel softening mechanism was revealed. The initial post-dynamic softening stage involved rapid growth of the dynamically formed nuclei and migration of the mobile boundaries in correspondence with the well-established metadynamic recrystallization (MDRX) mechanism. However, in contrast to the deformed matrix, SRX was not observed and the sub-boundaries within DRX grains rapidly disintegrated through dislocation climb and dislocation annihilation, which led to the formation of dislocation-free grains already at short holding times. Consequently, the DRX texture initially became slightly weakened and then remained largely preserved throughout the annealing process.


1983 ◽  
Vol 17 (10) ◽  
pp. 1231-1235 ◽  
Author(s):  
P.G. Shewmon ◽  
G. Meyrick ◽  
S. Mishra ◽  
T.A. Parthasarathy

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