Dislocation cell structure relationd =Kϱ−1/2: The stacking fault energy dependence ofK

1974 ◽  
Vol 22 (1) ◽  
pp. 299-304 ◽  
Author(s):  
M. J. Witcomb
Keyword(s):  
Energy Dependence ◽  
Cell Structure ◽  
Dislocation Cell ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Dislocation Cell Structure

TEM study on fine carbide precipitates and dislocation cell structure

1990 ◽  
Vol 48 (4) ◽  
pp. 904-905
Author(s):  
Mengzhe Chen ◽  
Siqin Wang ◽  
Jun Ke
Keyword(s):  
Carbide Particle ◽  
Cell Structure ◽  
Ferrite Matrix ◽  
Dislocation Cell ◽  
Isothermal Treatment ◽  
Particle Sizes ◽  
Dislocation Cell Structure ◽  
Thin Foils ◽  
Hsla Steels ◽  
Fine Carbide

A series of investigations have been conducted into the nature and origin of the dislocation cell structure. R.J.Klassen calculated that the dislocation cell limiting size in pure ferrite matrix is about 0.4 μm. M.N.Bassion estimated the size of dislocation cell in deformed ferrite of HSLA steels to be of the same order.In this paper, TEM observation has been concentrated on the interaction of fine carbide precipitates with dislocation cell structure in deformed Fe-C-V (0.05%C, 0.13% and 0.57%V) and Fe-C-Nb (0.07 %C and 0.04%Nb) alloys and compared with that in Fe-C (0.05%). Specimens were austenitized at 1500 “C/20 min and followed by isothermal treatment at 750 °C and 800 “C for 20, 40 and 120 minutes . The carbide particle sizes in these steels are from 9 to 86nm measured from carbon extraction replicas. Specimens for TEM were cut from differently deformed areas of tensile specimens deformed at room temperture. The thin foils were jet electropolished at -20 C in a solution of 10% perchloric acid and 90% ethanol. The TEM observation was carried out in JEM 100CX , EM420 at 100kv and JEM 2000FX at 200kv.

In-situ observations of microvoid coalescence: Stacking fault energy effects

1990 ◽  
Vol 48 (4) ◽  
pp. 520-521
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Void Formation ◽  
Dislocation Cell ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Second Phase ◽  
Alternative Mechanism ◽  
Microvoid Coalescence ◽  
Fracture Surfaces ◽  
Cell Structures ◽  
Static Fracture

Although it has been well established that microvoid coalescence occurs during static or quasi-static fracture in ductile materials, the exact mechanism for microvoid formation is still unclear. It has been argued that microvoids initiate and grow from second phase particles. However this argument cannot be used to explain the existence of microvoids on the fracture surfaces of "pure" materials. An alternative mechanism for their formation in "pure" materials is that they initiate and grow along dislocation cell walls. If this premise is true; then the nature and extent of microvoid coalescence should be related to the stacking fault energy (SFE) of the material since the latter is a controlling parameter in the formation of dislocation cells. The relationship between microvoid coalescence and stacking fault energy may have some basis since absolute cell dimensions are of the same magnitude as the observed dimple sizes. The present study examines the effect of dislocation cell structures on the formation of microvoids as a function of the stacking fault energy of a given material through direct observation of the void formation and growth process within the TEM. The fundamental aspects of the work is to correlate the dislocation substructures, void initiation, growth, and coalescence to the resulting fracture surfaces.

Some Dislocation Features in Deformed Copper and Alpha Brass

1968 ◽  
Vol 26 ◽  
pp. 272-273
Author(s):  
F. I. Grace
Keyword(s):  
Shock Loading ◽  
Cell Structure ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
304 Stainless Steel ◽  
Cell Structures ◽  
Dislocation Arrays ◽  
A Cell ◽  
Silicon Bronze ◽  
Alpha Brass

The nature of the dislocation arrays in f.c.c. metals after conventional deformation has been shown to be a function of the stacking fault energy. For metals with high stacking fault energy, such as copper, nickel and aluminum, the dislocations responsible for plastic deformation appear in the form of a cell structure. When the stacking fault energy is low, cell structures are not observed. At present, there are indications that the stacking fault energy may also be important when unconventional means of deformation are encountered, as in the case of shock loading. Nolder and Thomas and Johari and Thomas observed cell structures in nickel and copper while Otte and Holland and Inman, Murr and Rose observed layered-type structures in silicon bronze and 304 stainless steel after shock deformation.

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