Formation of Persistent Slip Band in Fatigued Copper Single Crystals

1982 ◽  
Vol 40 ◽  
pp. 470-471
Author(s):  
N. Y. Jin
Keyword(s):  
Volume Fraction ◽  
Fatigue Cracks ◽  
Wall Structure ◽  
Matrix Structure ◽  
Dislocation Dipole ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
The Matrix ◽  
Hard Shell ◽  
Copper Single Crystals

Localised plastic deformation in Persistent Slip Bands(PSBs) is a characteristic feature of fatigue in many materials. The dislocation structure in the PSBs contains regularly spaced dislocation dipole walls occupying a volume fraction of around 10%. The remainder of the specimen, the inactive "matrix", contains dislocation veins at a volume fraction of 50% or more. Walls and veins are both separated by regions in which the dislocation density is lower by some orders of magnitude. Since the PSBs offer favorable sites for the initiation of fatigue cracks, the formation of the PSB wall structure is of great interest. Winter has proposed that PSBs form as the result of a transformation of the matrix structure to a regular wall structure, and that the instability occurs among the broad dipoles near the center of a vein rather than in the hard shell surounding the vein as argued by Kulmann-Wilsdorf.

The effect of high current pulsing on persistent slip bands in fatigued copper single crystals

2002 ◽  
Vol 332 (1-2) ◽  
pp. 351-355 ◽  
Author(s):  
Xiao Suhong ◽  
Zhou Yizhou ◽  
Guo Jingdong ◽  
Wu Shiding ◽  
Yao Ge ◽  
...  
Keyword(s):  
Single Crystals ◽  
High Current ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
Copper Single Crystals

Backstress, the Bauschinger Effect and Cyclic Deformation

2008 ◽  
Vol 604-605 ◽  
pp. 39-51 ◽  
Author(s):  
M.E. Kassner ◽  
P. Geantil ◽  
L.E. Levine ◽  
B.C. Larson
Keyword(s):  
Long Range ◽  
Cyclic Deformation ◽  
Bauschinger Effect ◽  
Internal Stresses ◽  
Dislocation Dipole ◽  
Crystalline Materials ◽  
X Ray ◽  
The Past ◽  
Slip Bands ◽  
Persistent Slip Bands

Backstresses or long range internal stresses (LRIS) in the past have been suggested by many to exist in plastically deformed crystalline materials. Elevated stresses can be present in regions of elevated dislocation density or dislocation heterogeneities in the deformed microstructures. The heterogeneities include edge dislocation dipole bundles (veins) and the edge dipole walls of persistent slip bands (PSBs) in cyclically deformed materials and cell and subgrain walls in monotonically deformed materials. The existence of long range internal stress is especially important for the understanding of cyclic deformation and also monotonic deformation. X-ray microbeam diffraction experiments performed by the authors using synchrotron x-ray microbeams determined the elastic strains within the cell interiors. The studies were performed using, oriented, monotonically deformed Cu single crystals. The results demonstrate that small long-range internal stresses are present in cell interiors. These LRIS vary substantially from cell to cell as 0 % to 50 % of the applied stress. The results are related to the Bauschinger effect, often explained in terms of LRIS.

The Half-Cycle Slip Activity of Persistent Slip Bands in Polycrystals

2007 ◽  
Vol 567-568 ◽  
pp. 123-127 ◽  
Author(s):  
A. Weidner ◽  
W. Tirschler ◽  
C. Blochwitz ◽  
Werner Skrotzki
Keyword(s):  
Volume Fraction ◽  
Half Cycle ◽  
Slip Systems ◽  
Large Scatter ◽  
Force Microscopy ◽  
Atomic Force ◽  
Slip Bands ◽  
Slip Activity ◽  
Persistent Slip Bands ◽  
Number Of Cycles

The development of the volume fraction of cumulated persistent slip bands (PSBs) in cyclically deformed nickel polycrystals was investigated in dependence on the number of cycles using scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was shown that there is a large scatter of the volume fraction of PSBs from grain to grain. Three different tendencies for the development of the volume fraction with increasing number of cycles were distinguished. It was shown that there is a correlation of the orientation of the primary slip systems with the volume fraction of cumulated PSBs and the activation of PSBs during half-cycle deformation.

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