GRAIN-SIZE DEPENDENCE OF FRACTURE IN COPPER–ALUMINIUM ALLOYS EMBRITTLED BY MERCURY

1967 ◽  
Vol 45 (2) ◽  
pp. 1235-1249 ◽  
Author(s):  
F. W. J. Pargeter ◽  
M. B. Ives
Keyword(s):  
Aluminium Alloys ◽  
Cellular Network ◽  
Size Dependence ◽  
Network Formation ◽  
Pure Copper ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Aluminium Content ◽  
Α Phase ◽  
Stacking Fault Energies

Polycrystalline specimens of α-phase copper–aluminium alloys of varying composition, amalgamated with mercury, have been deformed in tension in a soft tensile machine. In all cases, brittle intergranular failure occurred at stresses and strains below those required for fracture in air, the degree of embrittlement increasing with increasing aluminium content. The alloys having stacking-fault energies less than '~8 erg/cm2 were found to obey quite well the Petch–Stroh relation:[Formula: see text]The other alloys showed deviations from this relation which became more marked with increasing stacking-fault energy. Values of the fracture energy, varying from ~48 erg/cm2 for pure copper to ~470 erg/cm2 for Cu −8 wt.% Al, have been obtained for all of the alloys. These values are only applicable for relatively small grain sizes.The deviation from the Petch–Stroh relation in the high stacking-fault energy alloys is thought to be due to their tendency to show cross-slip and cellular-network formation, rather than coplanar arrays of dislocations as required by the Stroh model. The low stacking-fault energy alloys typically show well-defined pileups and so obey the Petch–Stroh relations, as expected.

scholarly journals Modeling of Stacking Fault Energy in Hexagonal-Close-Packed Metals

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Zhigang Ding ◽  
Shuang Li ◽  
Wei Liu ◽  
Yonghao Zhao
Keyword(s):  
Mechanical Properties ◽  
Ising Model ◽  
Theoretical Background ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Hexagonal Close Packed ◽  
Orientation Model ◽  
Generalized Stacking Fault ◽  
Supercell Model ◽  
Stacking Fault Energies

The deformation of metals is known to be largely affected by their stacking fault energies (SFEs). In the review, we examine the theoretical background of three normally used models, supercell model, Ising model, and bond orientation model, for the calculation of SFE of hexagonal-close-packed (hcp) metals and their alloys. To predict the nature of slip in nanocrystalline metals, we further review the generalized stacking fault (GSF) energy curves in hcp metals and alloys. We conclude by discussing the outstanding challenges in the modeling of SFE and GSF energy for studying the mechanical properties of metals.

scholarly journals Diffraction Contrast from Dissociated Frank Dislocations. II. Comparison of Experimental and Computed Electron Micrographs

1969 ◽  
Vol 22 (3) ◽  
pp. 371 ◽  
Author(s):  
LM Clarebrough ◽  
AJ Morton
Keyword(s):  
Electron Micrographs ◽  
Aluminium Alloys ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Dislocation Loops ◽  
Degree Of Dissociation ◽  
Diffraction Contrast

Experimental and computed images for edges of Frank dislocation loops in quenched copper-aluminium alloys and in quenched silver are compared. The comparison shows that Frank dislocations are dissociated in these materials. By matching the computed and experimental images, the degree of dissociation is determined and the stacking fault energy of the various materials is estimated.

The dissociation of dislocations in silicon

1971 ◽  
Vol 325 (1563) ◽  
pp. 543-554 ◽  
Keyword(s):  
Electron Microscopy ◽  
Dislocation Line ◽  
Anisotropic Elasticity ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Weak Beam ◽  
Partial Dislocations ◽  
A Value ◽  
Beam Method ◽  
Stacking Fault Energies

The weak-beam method of electron microscopy (Cockayne, Ray & Whelan 1969, 1970) has been used to investigate the dissociation of dislocations in silicon. Total dislocations with a/2<110> Burgers vectors were found to be dissociated into Shockley partial dislocations, with a separation of 7.5 +0.6 nm (75 + 6 Å) for the pure edge orientation and 4.1 +0.6 nm (41+ 6 Å) for the pure screw orientation. The intrinsic stacking-fault energy, calculated from the measured dissociation width using anisotropic elasticity theory, is 51 + 5 mJ m -2 (51 + 5 erg cm -2 ). The method has also been used to image partial dislocations at threefold dislocation nodes in silicon. All nodes in the specimens examined were found to be extended, and of about the same size, indicating that the intrinsic and extrinsic stacking-fault energies are comparable. Measurements of the radii of curvature of partial dislocations at the nodes gave a value of 50+15 mJ m -2 (50+15 erg cm -2 ) for the intrinsic stacking fault energy, using the method of Whelan (1959) as modified by Brown & Thölén (1964). Dislocations in silicon specimens annealed at a high temperature were found to be constricted along segments of the dislocation line. Evidence is presented which suggests that the constricted segments have climbed out of the slip plane.

Deformation Properties of Austenitic Stainless Steels with Different Stacking Fault Energies

2018 ◽  
Vol 941 ◽  
pp. 190-197 ◽  
Author(s):  
Dávid Molnár ◽  
Göran Engberg ◽  
Wei Li ◽  
Levente Vitos
Keyword(s):  
Stainless Steels ◽  
Electron Backscatter Diffraction ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Austenitic Steels ◽  
Uniaxial Tensile ◽  
Tensile Behaviour ◽  
Uniaxial Tensile Testing ◽  
Deformation Properties ◽  
Stacking Fault Energies

In FCC metals a single parameter – stacking fault energy (SFE) – can help to predict the expectable way of deformation such as martensitic deformation, deformation twinning or pure dislocation glide. At low SFE one can expect the perfect dislocations to dissociate into partial dislocations, but at high SFE this separation is more restricted. The role of the magnitude of the stacking fault energy on the deformation microstructures and tensile behaviour of different austenitic steels have been investigated using uniaxial tensile testing and electron backscatter diffraction (EBSD). The SFE was determined by using quantum mechanical first-principles approach. By using plasticity models we make an attempt to explain and interpret the different strain hardening behaviour of stainless steels with different stacking fault energies.

scholarly journals Atomic structure, electronic properties and generalized stacking fault energy of diamond/c-BN multilayer

RSC Advances ◽  
2017 ◽  
Vol 7 (47) ◽  
pp. 29599-29605 ◽  
Author(s):  
Zijun Lin ◽  
Xianghe Peng ◽  
Cheng Huang ◽  
Tao Fu ◽  
Zhongchang Wang
Keyword(s):  
Electronic Properties ◽  
Atomic Structure ◽  
First Principles ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
First Principles Calculations ◽  
Atomic Structures ◽  
Generalized Stacking Fault ◽  
Stacking Fault Energies ◽  
Generalized Stacking Fault Energy

The atomic structures, electronic properties and generalized stacking fault energies of the diamond/c-BN multilayer are investigated systematically with first-principles calculations.

scholarly journals Quantified Static Recovery Trend of Constricted Jogs of Aluminium Alloys During Annealing

2021 ◽  
Vol 71 (6) ◽  
pp. 822-825
Author(s):  
Prantik Mukhopadhyay
Keyword(s):  
Aluminium Alloys ◽  
Annealing Temperature ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Processing Temperature ◽  
Flow Strength ◽  
Static Recovery ◽  
Grain Structures ◽  
Wide Range ◽  
Final Tempering

The static recovery of dislocations in aluminium alloys is known to observe during re-heating and inter-annealing of aluminium alloys, so that the fully recrystallised and partially recrystallised grain structures are deliberated respectively for a judicious control on their final tempering of strength, ductility, toughness and crystallographic texture to eliminate the earing related problems. An elaborate physical based static recovery simulator is required to address the trend of dislocation recovery during the time of industrial annealing to evaluate the extent of discontinuously and continuously developed recrystallised aluminium alloys. New industrial annealing practices to develop an extensively wide range of aluminium alloys with the medium to low stacking fault energy range, suitable for their plenty of use in defence vehicles, inevitably demand quantified dislocation density, the decisive element of flow strength. The formulated static recovery rate of the constricted dislocation jogs increases with the stacking fault energy and increases with the industrial annealing temperature. The formulated static recovery of dislocations is found to be very precise and concentric to address the process and materials characteristics, so that it would be liable to define the minute change in the processing temperature, i.e. 50K.

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