Stacking Faults in Crystals

1968 ◽  
Vol 26 ◽  
pp. 250-251
Author(s):  
P. C. J. Gallagher
Keyword(s):  
Stacking Faults ◽  
Elastic Equilibrium ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Major Influence ◽  
Face Centered Cubic ◽  
Degree Of Dissociation ◽  
Partial Dislocations ◽  
Layer Structures ◽  
Face Centered

Stacking faults are an important substructural feature of many materials, and have been widely studied in layer structures (e.g. talc) and in crystals with hexagonal and face centered cubic structure. Particular emphasis has been placed on the study of faulted defects in f.c.c. alloys, since the width of the band of fault between dissociated partial dislocations has a major influence on mechanical properties.Under conditions of elastic equilibrium the degree of dissociation reflects the balance of the repulsive force between the partials bounding the fault, and the attractive force associated with the need to minimize the energy arising from the misfits in stacking sequence. Examples of two of the faulted defects which can be used to determine this stacking fault energy, Υ, are shown in Fig. 1. Intrinsically faulted extended nodes (as at A) have been widely used to determine Υ, and examples will be shown in several Cu and Ag base alloys of differing stacking fault energy. The defect at B contains both extrinsic and intrinsic faulting, and readily enables determination of both extrinsic and intrinsic fault energies.

Dislocations and stacking faults in stainless steel

1957 ◽  
Vol 240 (1223) ◽  
pp. 524-538 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Thin Sections ◽  
Partial Dislocations ◽  
Transmission Electron

Further experiments by transmission electron microscopy on thin sections of stainless steel deformed by small amounts have enabled extended dislocations to be observed directly. The arrangement and motion of whole and partial dislocations have been followed in detail. Many of the dislocations are found to have piled up against grain boundaries. Other observations include the formation of wide stacking faults, the interaction of dislocations with twin boundaries, and the formation of dislocations at thin edges of the foils. An estimate is made of the stacking-fault energy from a consideration of the stresses present, and the properties of the dislocations are found to be in agreement with those expected from a metal of low stacking-fault energy.

Selected Values for the Stacking Fault Energy of Face Centered Cubic Metals

2008 ◽  
Vol 591-593 ◽  
pp. 708-711 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
High Resolution Electron Microscopy ◽  
Accurate Method ◽  
Stacking Fault ◽  
Metals And Alloys ◽  
Stacking Fault Energy ◽  
Face Centered Cubic ◽  
Resolution Electron ◽  
Plastic Deformation Behavior ◽  
Face Centered ◽  
The 1960S

The Stacking fault energy (SFE) is an important parameter for metals and alloys. The plastic deformation behavior of face centered cubic (FCC) metals and alloys is directly related to the SFE values. The several methods for determining SFE are critically discussed. The values reported in the 1960s and early 1970s are, in general, 20-30% overestimated. The node dislocation method, due to Whelan, overestimates the SFE. The method based on the critical resolved shear stress is not reliable. The most accurate method is the direct observation of dissociated partials by weak beam in TEM or using HREM (High resolution electron microscopy). Indirect methods based in X-Ray Diffraction and texture may provide reasonable estimates since reliable SFE values of reference metals are available. Selected SFE values for Ni, Cu, Ag, Cu and Al are presented.

Stacking fault energy of face-centered-cubic high entropy alloys

2018 ◽  
Vol 93 ◽  
pp. 269-273 ◽  
Author(s):  
S.F. Liu ◽  
Y. Wu ◽  
H.T. Wang ◽  
J.Y. He ◽  
J.B. Liu ◽  
...  
Keyword(s):  
Stacking Fault ◽  
Stacking Fault Energy ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Face Centered

Relaxation of Capped Strained Layers Via the Formation of Microtwins

1990 ◽  
Vol 202 ◽  
Author(s):  
D. M. Hwang ◽  
S. A. Schwarz ◽  
T. S. Ravi ◽  
R. Bhat ◽  
C. Y. Chen
Keyword(s):  
Strain Relaxation ◽  
Stacking Fault ◽  
Face Centered Cubic ◽  
Strained Layers ◽  
Strained Layer ◽  
Fundamental Limitations ◽  
Partial Dislocations ◽  
Relaxation Channel ◽  
Kink Model ◽  
Face Centered

ABSTRACTA new strain relief mechanism in epitaxial layers of lattice mismatched face-centered cubic materials is identified using transmission electron microscopy. For an embedded strained layer near its critical thickness, we find that the primary strain-relaxation channel is through the formation of microtwins. A monolayer microtwin (a stacking fault) spanning the strained layer can form when a pair of partial dislocations of the <112> /6 type with antiparallel Burgers vectors are generated inside the strained layer and glide to the opposite interfaces. A series of partial dislocations can result in a microtwin several monolayers thick. For embedded strained layers of materials with small stacking fault energy, the formation of partial dislocation pairs is an energetically-favored strain relaxation channel, as compared to the formation of perfect dislocation pairs in the conventional double-kink model. Therefore, the mechanism proposed here poses fundamental limitations for strained layer device structures.

FAULTED DEFECTS AND STACKING-FAULT ENERGY

1967 ◽  
Vol 45 (2) ◽  
pp. 1135-1146 ◽  
Author(s):  
L. M. Clarebrough ◽  
P. Humble ◽  
M. H. Loretto
Keyword(s):  
Direct Methods ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Face Centered Cubic ◽  
Dislocation Loops ◽  
Cubic Metals ◽  
The Third ◽  
Stacking Fault Tetrahedra ◽  
Dislocation Energy ◽  
Face Centered

Four direct methods of obtaining values of stacking-fault energy from observation of faulted defects in pure face-centered cubic metals are discussed. It is shown that there is essential agreement between the method based on the observation of threefold nodes and that based on the observation of triangular Frank dislocation loops and stacking-fault tetrahedra in deformed f.c.c. metals, in the range where both methods are applicable. On the other hand, it is shown that the third method, based on the collapse size of stacking-fault tetrahedra in quenched metals, cannot yield even an upper limit. New experimental results show that the fourth method, based on the annealing rate of faulted loops, is applicable only to metals of high stacking-fault energy and then only if jog nucleation and propagation are not rate controlling; for low stacking-fault energy metals, these factors, together with the dislocation energy, must be considered, and cannot be completely taken into account.

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