Three-dimensional characterization of superplastic grain boundary sliding inside Al–Zn–Mg–Cu alloy sheet

2019 ◽  
Vol 164 ◽  
pp. 82-85 ◽  
Author(s):  
Hiroshi Masuda ◽  
Hirobumi Tobe ◽  
Toru Hara ◽  
Eiichi Sato
Keyword(s):  
Grain Boundary ◽  
Three Dimensional ◽  
Grain Boundary Sliding ◽  
Alloy Sheet ◽  
Cu Alloy ◽  
Boundary Sliding

scholarly journals Modelling of the densification of polar firn: characterization of the snow–firn transition

1998 ◽  
Vol 26 ◽  
pp. 39-44 ◽  
Author(s):  
L. Arnaud ◽  
V. Lipenkov ◽  
J. M Barnola ◽  
M. Gay ◽  
P. Duval
Keyword(s):  
Grain Boundary ◽  
Power Law ◽  
Grain Boundary Sliding ◽  
Boundary Sliding ◽  
Power Law Creep

The transformation of dry snow to firn is described by the transition between densification by deformationless restacking and densification by power-law creep. The observed decrease with temperature of the density at the snow-firn transition seems to result from the competition between grain-boundary sliding and power-law creep. These two densification processess occur concurrently in snow, although there are probably micro-regions in which sliding alone occurs. Validation of a geometrical densification model developed for ceramics has been obtained from densification data from several Antarctic and Greenland sites and from the characterization of the structure of polar firn.

scholarly journals Modelling of the densification of polar firn: characterization of the snow–firn transition

1998 ◽  
Vol 26 ◽  
pp. 39-44 ◽  
Author(s):  
L. Arnaud ◽  
V. Lipenkov ◽  
J. M Barnola ◽  
M. Gay ◽  
P. Duval
Keyword(s):  
Grain Boundary ◽  
Power Law ◽  
Grain Boundary Sliding ◽  
Boundary Sliding ◽  
Power Law Creep

The transformation of dry snow to firn is described by the transition between densification by deformationless restacking and densification by power-law creep. The observed decrease with temperature of the density at the snow-firn transition seems to result from the competition between grain-boundary sliding and power-law creep. These two densification processess occur concurrently in snow, although there are probably micro-regions in which sliding alone occurs. Validation of a geometrical densification model developed for ceramics has been obtained from densification data from several Antarctic and Greenland sites and from the characterization of the structure of polar firn.

scholarly journals Superplastic Tensile Deformation Behavior and Microstructural Evolution of Al–Zn–Mg–Cu Alloy

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 941
Author(s):  
Guangyu Li ◽  
Hua Ding ◽  
Jian Wang ◽  
Ning Zhang ◽  
Hongliang Hou
Keyword(s):  
Grain Boundary ◽  
Microstructural Evolution ◽  
Superplastic Deformation ◽  
Tensile Deformation ◽  
Grain Boundary Sliding ◽  
Recrystallization Process ◽  
Grain Rotation ◽  
Texture Intensity ◽  
Cu Alloy ◽  
Boundary Sliding

The microstructural evolution of the Al–Zn–Mg–Cu alloy during the superplastic deformation process has been studied by high temperature tensile experiment. The superplastic deformation behaviors are investigated under different temperatures of 470 °C, 485 °C, 500 °C, 515 °C and 530 °C, and different strain rates of 3 × 10−4 s−1, 1 × 10−3 s−1, 3 × 10−2 s−1 and 1 × 10−2 s−1. The microstructure observation shows that uniform and equiaxed grains can be obtained by dynamic recrystallization in the initial stage of superplastic deformation. Once the recrystallization process has been finished, the variations of the fraction of high angle boundary, the grain aspect ratio and the Schmid factor are negligible during the superplastic deformation, which shows that the grain boundary sliding and grain rotation are the main deformation mechanisms. The maximum texture intensity decreases compared with the initial microstructure, indicating that grain boundary sliding and grain rotation can weaken the texture, however, the texture intensity increases in the final stage of superplastic deformation, which may be resulted from the stress concentration.

A formulation for anisotropy in diffusional creep

1992 ◽  
Vol 436 (1896) ◽  
pp. 187-196 ◽  
Keyword(s):  
Grain Boundary ◽  
Elastic Anisotropy ◽  
Creep Behaviour ◽  
Grain Boundary Sliding ◽  
Diffusional Creep ◽  
Sources And Sinks ◽  
Boundary Sliding ◽  
Compliance Matrices

Grain shape can introduce anisotropy in creep which depends on the diffusion of vacancies between grain boundary sources and sinks. Such anisotropy is examined to determine the rate of creep under multiaxial stresses both for lattice and grain boundary diffusion. Noting the role of grain boundary sliding in this form of creep it is shown that, with some approximations that only become significant in an identified case, complete and fully self-consistent formulae can be derived for the rate of creep in terms of grain dimensions. The results are presented in the form of compliance matrices which are analogous to those that have a well-established role in the characterization of elastic anisotropy. A comparable usefulness of these ‘creep compliance coefficients’ is envisaged in evaluating anisotropic diffusional creep behaviour and a similar approach can be extended to more general cases where creep rates may be interface controlled.

The microstructure of Sn in near-eutectic Sn–Ag–Cu alloy solder joints and its role in thermomechanical fatigue

2004 ◽  
Vol 19 (6) ◽  
pp. 1608-1612 ◽  
Author(s):  
Donald W. Henderson ◽  
James J. Woods ◽  
Timothy A. Gosselin ◽  
Jay Bartelo ◽  
David E. King ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Grain Boundary Sliding ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Alloy Solder ◽  
Boundary Sliding ◽  
Solder Joint Fatigue ◽  
And Diffusion

During the solidification of solder joints composed of near-eutectic Sn–Ag–Cu alloys, the Sn phase grows rapidly with a dendritic growth morphology, characterized by copious branching. Notwithstanding the complicated Sn growth topology, the Sn phase demonstrates single crystallographic orientations over large regions. Typical solder ball grid array joints, 900 μm in diameter, are composed of 1 to perhaps 12 different Sn crystallographic domains (Sn grains). When such solder joints are submitted to cyclic thermomechanical strains, the solder joint fatigue process is characterized by the recrystallization of the Sn phase in the higher deformation regions with the production of a much smaller grain size. Grain boundary sliding and diffusion in these recrystallized regions then leads to extensive grain boundary damage and results in fatigue crack initiation and growth along the recrystallized Sn grain boundaries.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

INTERNAL FRICTION PEAKS CONNECTED WITH GRAIN BOUNDARY SLIDING IN Al

1983 ◽  
Vol 44 (C9) ◽  
pp. C9-759-C9-764
Author(s):  
E. Bonetti ◽  
A. Cavallini ◽  
E. Evangelista ◽  
P. Gondi
Keyword(s):  
Internal Friction ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Boundary Sliding
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