Twinning in Ti-48%Ni-2%Fe Single Crystals under Rolling

2013 ◽  
Vol 738-739 ◽  
pp. 118-122
Author(s):  
Margarita Isaenkova ◽  
Yuriy Perlovich ◽  
Vladimir Fesenko ◽  
Tatyana Dementyeva
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Single Crystals ◽  
Stereographic Projection ◽  
Rolling Temperature ◽  
Main Mechanism ◽  
Geometrical Analysis ◽  
Pole Figures

Under rolling of Ti-48%Ni-2%Fe single crystals in the phase B2 at 350oC the twinning is the main mechanism of plastic deformation by many initial orientations of these single crystals, as texture data show clearly. Splitting of initial maxima in the stereographic projection of single crystal into several new ones is an evident manifestation of twinning. But this mode of reorientation is observed only at initial stages of rolling, when deformation degrees do not exceed ~10-15%. A geometrical analysis of pole figures for rolled single crystals showed, that at the used rolling temperature the preferable twinning planes there were {114} and {118}.

scholarly journals The critical shear stress of mercury single crystals

1937 ◽  
Vol 163 (912) ◽  
pp. 34-53 ◽  
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Melting Point ◽  
Single Crystal ◽  
Single Crystals ◽  
Critical Shear Stress ◽  
Impurity Content ◽  
Thermal Agitation ◽  
Plastic Yield ◽  
Metal Single Crystals

The influence of very small quantities of impurity on the critical shear stress of metal single crystals has an important bearing on the mechanism of their plastic deformation. For investigations in this field, mercury is a very suitable metal: its impurity content can easily be reduced to an extremely low level (Hulett 1911) and it contains no dissolved gases (Hulett 1911). Also, as first pointed out by Andrade (1914), single crystal wires of this metal can be prepared without difficulty. The low melting point of mercury (-38∙8° C.) is far from being a disadvantage. The crystals can be maintained at -60° C., and at a temperature so near the melting point the thermal agitation may be expected to accentuate phenomena not observable at lower temperatures, if such agitation plays the important part in the mechanism of glide ascribed to it (Taylor 1934; Polanyi 1934; Orowan 1934). As a possible instance of this, the experiments to be described have revealed the existence of a preliminary “set” preceding the true plastic yield. Widely differing forms of slip band have also been observed, and are described elsewhere (Greenland 1937). It is hoped that these results will throw further light on the mechanism of glide.

Influence of the Crystallographic Orientation of CuZn30 Single Crystal on the Portevin-Le Chatelier Effect

2013 ◽  
Vol 203-204 ◽  
pp. 406-410 ◽  
Author(s):  
Barbara Grzegorczyk ◽  
Wojciech Ozgowicz ◽  
Elżbieta Kalinowska-Ozgowicz
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystallographic Orientation ◽  
Stress And Strain ◽  
Complex Process ◽  
Orientation Axis ◽  
Chatelier Effect ◽  
Stress And Strain Rate

Plastic deformation of solid crystals is a complex process, mostly heterogeneous, due to the simultaneous effect of several deformation mechanisms. A dominating deformation mechanism depends on the properties of the material and external coefficients, viz. temperature, stress and strain rate. The applied Bridgman method permitted to obtain single crystal of the CuZn30 alloy adequate for plastic deformation investigations. Single crystal are characterized by selected crystallographic orientations from various areas of the basic triangle. In order to determine the influence of the crystallographic orientation on the Portevin-Le Chatelier effect selected single crystals were compressed at a temperature of 300°C at a strain rate of 10-3 s-1. Experiments confirmed the effect of the crystallographic orientation axis of CuZn30 single crystals on the observed differences in the intensity of stress oscillation on stress-strain curves.

scholarly journals The mechanism of plastic deformation of crystals. Part I.—Theoretical

1934 ◽  
Vol 145 (855) ◽  
pp. 362-387 ◽  
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Shear Strain ◽  
Single Crystals ◽  
Rock Salt ◽  
Theory Of Elasticity ◽  
Crystal Plane ◽  
Lateral Movement

Experiments on the plastic deformation of single crystals, of metals and of rock salt have given results which differ in detail but possess certain common characteristics. In general the deformation of a single crystal in tension or compression consists of shear strain in which sheets of the crystal parallel to a crystal plane slip over one another, the direction of motion being some simple crystal-lographic axis. The measure of this strain, which will be represented by s , is the ration of the relative lateral movement of two parallel planes of slip to the distance between them. Thus it is defined in the same way as the shear strain considered in the theory of elasticity.

Regular Substructure Inhomogeneity of Textured Materials by the Example of Rolled Ti-Ni Single Crystals

2005 ◽  
Vol 105 ◽  
pp. 207-212
Author(s):  
Yuriy Perlovich ◽  
Margarita Isaenkova ◽  
Vladimir Fesenko ◽  
Hans Joachim Bunge
Keyword(s):  
Plastic Deformation ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Mechanisms ◽  
Crystalline Lattice ◽  
Texture Formation ◽  
Ray Method ◽  
X Ray ◽  
Pole Figures ◽  
Textured Materials

The substructure inhomogeneity of rolled Ti-48%Ni-2%Fe single crystals was studied by the X-ray method of Generalized Pole Figures. Under rolling of single crystals, along with texture formation, the nonuniform substructure develops. It is conditioned by inhomogeneous reorientation of the crystalline lattice and local differences in predominant plastic deformation mechanisms. The distribution of residual deformation effects is controlled by the orientation of separate regions relative to texture maxima. Rolled single crystals prove to be divided into subcomponents with close orientations and opposite signs of elastic microstrains.

Fragmentation, Texturing and Plastic Flow in the Subsurface of Friction-Processed Copper Single Crystal

2013 ◽  
Vol 872 ◽  
pp. 30-35 ◽  
Author(s):  
Andrey V. Chumaevsky ◽  
Dmitry V. Lychagin ◽  
Sergei Yu. Tarasov ◽  
Alexandr Melnikov
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystal Orientation ◽  
Normal Load ◽  
Dry Sliding ◽  
Texture Formation ◽  
Load Axis ◽  
Copper Single Crystals

Copper single crystals grown according to the Bridgman method and having their axes [] or [11 aligned with the normal load axis were processed by dry sliding. As shown, sliding-induced severe plastic deformation occurred in the subsurface of single crystals and caused formation of a lip by mechanism of texture formation. The SEM structure of this lip was found to be composed of fragments with their shapes dependent on the single crystal orientation with respect to normal load and friction force.

Research of Stress Field Distribution in FCC-Single Crystal Samples in Compression

2014 ◽  
Vol 682 ◽  
pp. 485-490 ◽  
Author(s):  
E. Alferova ◽  
D. Lychagin ◽  
A. Chernyakov
Keyword(s):  
Plastic Deformation ◽  
Finite Elements ◽  
Stress Field ◽  
Single Crystal ◽  
Single Crystals ◽  
Field Distribution ◽  
Isotropic Material ◽  
Tension Stress ◽  
Compression Axis ◽  
Crystallographic Orientations

.Theoretical distribution of a stress field in a sample in the form of a rectangular parallelepiped in compression for an isotropic material was calculated using the method of finite elements. Calculations showed that the highest stress is observed at the top and front edges of a sample. There are areas of the tension stress on vertical edges in the area of sample tops. Shift anisotropy was determined by imposing of the distributed tension field in a sample on FCC crystal of a certain crystallographic orientation.Change of shift symmetry in single crystals for different crystallographic orientations of a compression axis was considered. It was established that a shift fragmentation in the parallel octahedral planes in the conditions of plastic deformation determines the process of low-symmetric shift deformation and maintenance of higher single crystal pseudo-symmetry. Connection of the obtained results and test data on heterogeneity of plastic deformation of nickel and aluminum single crystals is discussed.

THE EFFECTS OF GRAIN BOUNDARIES ON THE PLASTIC DEFORMATION OF ZINC CRYSTALS

1957 ◽  
Vol 35 (1) ◽  
pp. 38-47 ◽  
Author(s):  
G. B. Craig ◽  
B. Chalmers
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Basal Plane ◽  
Basal Slip ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

The tensile plastic deformation of single-crystal and tricrystal specimens of zinc was investigated by analysis of the external change in shape of the specimens, and of the changes in X-ray diffraction patterns. It was demonstrated that the single crystals deformed by slip on the basal plane, but pyramidal as well as basal slip occurred in specimens containing grain boundaries.

Rules of Fragmentation and Localization at Aluminium Single Crystal Division during Compression Test

2014 ◽  
Vol 1013 ◽  
pp. 84-90 ◽  
Author(s):  
Ludmila A. Teplyakova ◽  
Irina Bespalova ◽  
Tatyana Kunitsyna
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Single Crystals ◽  
Compression Test ◽  
Deformation Process ◽  
Front Face ◽  
Experimental Investigations ◽  
Macroscopic Level ◽  
Plastic Deformation Process ◽  
Deformation Relief

This work presents the results of experimental investigations into deformation relief formed at the faces of aluminium single crystals. The aim of the investigations was to define the rules of macro fragmentation and macro localisation processes in plastic deformation. It was established that for the families of maximum loaded planes {111} in the aluminium single crystals, one can differentiate volumes which aren't limited to the specimen's front face. It is assumed that shearing in these volumes is eased during plastic deformation due to the absence of a reverse stress. Moreover, it is suggested that such volumes are called volumes of eased slip (VES). In addition to this, the role played by the volume of eased slip at the macroscopic level during the plastic deformation process was examined.

Investigation of Three-Dimensional Stress Fields and Slip Systems for fcc Single-Crystal Superalloy Notched Specimens

2005 ◽  
Vol 127 (3) ◽  
pp. 629-637 ◽  
Author(s):  
Nagaraj K. Arakere ◽  
Shadab Siddiqui ◽  
Shannon Magnan ◽  
Fereshteh Ebrahimi ◽  
Luis E. Forero
Keyword(s):  
Plastic Deformation ◽  
Plastic Zone ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystallographic Orientation ◽  
Elastic Anisotropy ◽  
Three Dimensional ◽  
Stress Fields ◽  
Slip Systems ◽  
Zone Formation

Metals and their alloys, except for a few intermetallics, are inherently ductile, i.e., plastic deformation precedes fracture in these materials. Therefore, resistance to fracture is directly related to the development of the plastic zone at the crack tip. Recent studies indicate that the fracture toughness of single crystals depends on the crystallographic orientation of the notch as well as the loading direction. In general, the dependence of crack propagation resistance on crystallographic orientation arises from the anisotropy of (i) elastic constants, (ii) plastic deformation (or slip), and (iii) the weakest fracture planes (e.g., cleavage planes). Because of the triaxial stress state at the notch tips, many slip systems that otherwise would not be activated during uniaxial testing become operational. The plastic zone formation in single crystals has been tackled theoretically by Rice and his co-workers [Rice, J. R., 1987, Mech. Mater. 6, pp. 317–335; Rice, J. R., and Saeedvafa, M., 1987, J. Mech. Phys. Solids 36, pp. 189–214; Saeedvafa, M., and Rice, J. R., 1988; ibid., 37, pp. 673–691; Rice, J. R., Hawk, D. E., Asaro, R. J., 1990, Int. J. Fract. 42, pp. 301–321; Saeedvafa, M., and Rice, J. R., 1992, Modell. Simul. Mater. Sci. Eng. 1, pp. 53–71] and only limited experimental work has been conducted in this area. The study of the stresses and strains in the vicinity of a fcc single-crystal notch tip is of relatively recent origin. We present experimental and numerical investigation of three-dimensional (3D) stress fields and evolution of slip sector boundaries near notches in fcc single-crystal PWA1480 tension test specimens and demonstrate that a 3D linear elastic finite element model, which includes the effect of material anisotropy, is shown to predict active slip planes and sectors accurately. The slip sector boundaries are shown to have complex curved shapes with several slip systems active simultaneously near the notch. Results are presented for surface and mid-plane of the specimens. The results demonstrate that accounting for 3D elastic anisotropy is very important for accurate prediction of slip activation near fcc single-crystal notches loaded in tension. Results from the study will help establish guidelines for fatigue damage near single-crystal notches.

scholarly journals Microstructure and Texture of Hydrostatic Extrusion Deformed Ni Single Crystals and Polycrystal

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
D. Jakubowska ◽  
J. Zdunek ◽  
M. Kulczyk ◽  
J. Mizera ◽  
K. J. Kurzydłowski
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Single Crystal ◽  
Single Crystals ◽  
Relevant Literature ◽  
Hydrostatic Extrusion ◽  
Total Deformation ◽  
Polycrystalline Nickel ◽  
Before And After

The differences in the microstructure and texture of two Ni single crystals, with different initial orientations (100and110), and of polycrystalline nickel, before and after severe plastic deformation (SPD) produced by hydrostatic extrusion (HE), have been investigated. The crystals were deformed by a two-step HE process with a total deformation value ofε=1.2. The global texture, mechanical properties, and microstructure were examined after the deformation. In every investigated sample, the presence of111fibre texture was noted, while the starting orientation of a100Ni single crystal was preserved in 50% of the volume. The results obtained were compared with the relevant literature data.

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