scholarly journals The Stress Induced Martensite-Austenite Interface in Fe-15Ni-15Cr Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 110-111
Author(s):  
G. A. Stone ◽  
G. Thomas
Keyword(s):  
Shear Stress ◽  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Habit Plane ◽  
Maximum Shear Stress ◽  
Crystal Axis ◽  
Surface Study

A single crystal stressed in the [3]𝛄 direction at 185°K was transformed to 5% 𝛂 martensite and 2% Ɛ martensite by volume. The austenite slip system of maximum shear stress is the (11)𝛄 [01)𝛄. Fig. 1 shows a two surface study using the electron and optical microscopes. The a martensite is confined between £martensite plates with the (0001)Ɛ ∥ (11)𝛄. The size of the acicular martensite crystals is controlled by the spacing of the £ martensite plates. These £ martensite plates are seen in Fig. 1A as dark vertical bands. The axes of the acicular crystals lie in the (11)𝛄 plane. The £ martensite habit plane is defined as the plane perpendicular to the (11)𝛄 containing the vector defining the crystal axis.

Mechanical behavior assessment of sucrose using nanoindentation

2007 ◽  
Vol 22 (7) ◽  
pp. 2037-2045 ◽  
Author(s):  
K.J. Ramos ◽  
D.F. Bahr
Keyword(s):  
Experimental Study ◽  
Plastic Deformation ◽  
Shear Stress ◽  
Elastic Modulus ◽  
Slip System ◽  
Single Crystals ◽  
Maximum Shear Stress ◽  
Model Material ◽  
Instrumented Indentation ◽  
Plastic Properties

An experimental study of the elastic and plastic properties of sucrose single crystals, which can be considered to be a model material for both pharmaceutical excipients and explosives, has been carried out using nanoindentation. Instrumented indentation was used to characterize the properties of both habit and cleavage planes on the (100) and (001) orientations; the elastic modulus on the (100) is 38 GPa, while the modulus on the (001) is 33 GPa. The hardness of sucrose is approximately 1.5 GPa. Nanoindentation enables assessment of the onset of plastic deformation on cleaved surfaces, and a maximum shear stress of 1 GPa can be supported prior to plastic deformation. The deformation in this material is crystallographically dependent, with pileup around residual indentation impressions showing evidence of preferential slip system activity.

The Effect of Solid Solution Impurities on Dislocation Nucleation in a (001) Mo – 1.5 at.% Ir Single Crystal

2010 ◽  
Vol 662 ◽  
pp. 85-93
Author(s):  
Sergey Dub ◽  
Igor Zasimchuk ◽  
Leonid Matvienko
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Shear Stress ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Single Crystals ◽  
Free Volume ◽  
Dislocation Nucleation ◽  
Initial Portion ◽  
G 12

Mechanical properties of (001) Mo and (001) Mo – 1.5 at.% Ir single crystals have been studied by nanoindentation. It has been found that the iridium addition to molybdenum leads to an increase in both hardness and elastic modulus. An abrupt elasto-plastic transition (pop-in) at a depth of about 20 - 40 nm caused by dislocation nucleation in previously dislocation-free volume has been observed in the initial portion of the loading curve. It has shown that the Ir addition essentially affects the dislocation nucleation. Mean shear stress required for the dislocation nucleation increased from 10.8 GPa (G/12) for a Mo single crystal to 18.2 GPa (G/8) for the Mo – 1.5 at% Ir solid solution. Thus, the Ir solution in a Mo single crystal affects not only the resistance to the motion of dislocations (hardness) but the nucleation of them as well. The latter is likely to occur as a result of an increase in the structure perfection of the Mo – 1.5 at% Ir solid solution as compared to the pure Mo single crystal.

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.

Kink and Crack Interfaces in Deformed 6H-SiC Single Crystals

1994 ◽  
Vol 357 ◽  
Author(s):  
X. J. Ning ◽  
P. Pirouz
Keyword(s):  
Low Temperature ◽  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Basal Plane ◽  
Prism Plane ◽  
Secondary Slip ◽  
Micro Cracks ◽  
Indentation Tests ◽  
Temperature Deformations

AbstractWhen a 6H-SiC single crystal is deformed under indentation or uniaxial compression in orientations not favorable for the activation of the 1/3[1120](0001) easy glide system, the secondary slip system is activated. Additionally, for low- temperature deformations, “kinks” and/or micro-cracks form in the crystal. In this paper, experimental results on relatively lowtemperature compression and indentation tests of single crystal 6H-SiC, and the microstructure of the deformed crystals, are presented. Based on the results, the secondary slip system in 6HSiC has been determined to be 1/3[1120](1100), which may actually be a combination of alternate glide of 1/3[1120] dislocations on the (1102) and (1102) planes. Further, dislocation mechanisms for the nucleation of prism-plane and basal-plane cracks, and for the process of kinking, in deformed 6H-SiC are proposed.

Dynamic Shear Stress—Analysis of Single Crystal Machining Studies

1973 ◽  
Vol 95 (4) ◽  
pp. 939-944 ◽  
Author(s):  
S. Ramalingam ◽  
J. Hazra
Keyword(s):  
Shear Stress ◽  
Single Crystal ◽  
Stress Analysis ◽  
Single Crystals ◽  
Plastic Flow ◽  
Metal Cutting ◽  
Dynamic Shear ◽  
Polycrystalline Aluminum ◽  
Cutting Problem ◽  
Good Agreement

Experimental results obtained when single crystals of aluminum of known orientation are machined under identical cutting conditions are presented. Analysis of the data obtained shows that the dynamic shear stress remains constant for all orientations tested and is in good agreement with the calculated value for polycrystalline aluminum. The implications of these results to metal cutting theory and the metal physical foundations on which the concept of dynamic shear stress, as a true material property, rests are discussed. The possible role that the dynamic shear stress may play in determining the geometry of the metal cutting problem, a problem in partially constrained plastic flow of metals, is discussed.

Rolling Anisotropy of Ni3Al Single Crystals

1986 ◽  
Vol 81 ◽  
Author(s):  
Katsuya Watanabe ◽  
Masaaki Fukuchi
Keyword(s):  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Rolling Direction ◽  
Sheet Plane ◽  
Active Slip System ◽  
Active Slip

AbstractThe rolling anisotropy of Ni3Al single crystals was studied. A single crystal sheet in the (011) plane showed remarkable anisotropy. Rolling the sheet in the [100] direction was simple but was almost impossible in the [011] direction. Substantial anisotropy was not observed in the (111) and (001) sheets. The texture of the rolled (011) and (111) sheets were {011}<011>. It is concluded that the rolling anisotropy of single crystal sheets is determined by the presence of active slip system related to compressive strain normal to the sheet plane, and tensile strain parallel to the rolling direction.

Orientation Dependence of Cycle Stability of Superelasticity Response in Quenched and Aged Ferromagnetic Co35Ni35Al30 Single Crystal

2014 ◽  
Vol 1040 ◽  
pp. 119-123 ◽  
Author(s):  
A.S. Eftifeeva ◽  
E.Yu. Panchenko ◽  
Yuri Chumlyakov
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
High Strength ◽  
Orientation Dependence ◽  
Cycle Stability ◽  
Axis Orientation ◽  
Crystal Axis ◽  
Nanoscale Particles ◽  
Stress Hysteresis

Using Co35Ni35Al30(at.%) single crystals the effects of crystals axis orientation and ageing at 673 K for 0.5 h in free state on superelasticity responses in compression are investigated. Ageing of these single crystals is found to result in strengthening of the high-temperature В2 phase and L10martensite, twofold increasing of temperature interval of SE response and weakening of the orientation dependence and improving the cycle stability of superelasticity response. In [011]- and [123]-oriented single crystals the values of the stress hysteresis decrease a nearly threefold as compared to the quenched state. The combination of high-strength [001] crystal axis orientation and precipitation of coherent nanoscale particles leads to the best stability of SE response in aged Co35Ni35Al30single crystals.

The slip modes of titanium and the effect of purity on their occurrence during tensile deformation of single crystals

1954 ◽  
Vol 226 (1165) ◽  
pp. 216-226 ◽  
Keyword(s):  
Shear Stress ◽  
Slip System ◽  
Single Crystals ◽  
Tensile Deformation ◽  
Interstitial Impurity ◽  
Slip Systems ◽  
Slip Planes ◽  
Critical Resolved Shear Stress ◽  
Interstitial Elements

Single-crystal test specimens of van Arkel titanium were obtained by a modification of the strain anneal technique.The modes of slip have been identified as (101̄0) [112̄0],(101̄1) [112̄0], and (0001) [112̄0]. It has been shown that not only does the interstitial impurity affect the magnitude of the critical resolved shear stress but also the relative values for the three slip systems. (101̄0) is the principal slip system and is favoured by increasing purity. A possible mechanism for the role of oxygen and nitrogen in this effect is put forward wherein it is shown that the interstitial sites occupied are such that interstitial elements render slip more difficult on two of the three slip planes in titanium.

Slip systems and critical resolved shear stress in pyrite: an electron backscatter diffraction (EBSD) investigation

2008 ◽  
Vol 72 (6) ◽  
pp. 1181-1199 ◽  
Author(s):  
C. D. Barrie ◽  
A. P. Boyle ◽  
S. F. Cox ◽  
D. J. Prior
Keyword(s):  
Shear Stress ◽  
Slip System ◽  
Single Crystal ◽  
Electron Backscatter Diffraction ◽  
Lattice Rotation ◽  
Slip Systems ◽  
Boundary Trace ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Critical Resolved Shear Stress

AbstractA suite of experimentally deformed single-crystal pyrite samples has been investigated using electron backscatter diffraction (EBSD). Single crystals were loaded parallel to <100> or <110> and deformed at a strain rate of 10-5s-1, confining pressure of 300 MPa and temperatures of 600°C and 700°C. Although geometrically (Schmid factor) the {001}<100> slip system should not be activated in <100> loaded samples, lattice rotation and boundary trace analyses of the distorted crystals indicate this slip system is easier to justify. Determination of 75 MPa as the critical resolved shear stress (CRSS) for {001}<100> activation, in the <110> loaded crystals, suggests a crystal misalignment of ~5—15° in the <100> loaded crystals would be sufficient to activate the {001}<100> slip system. Therefore, {001}<100> is considered the dominant slip system in all of the single-crystal pyrite samples studied. Slip-system analysis of the experimentally deformed polycrystalline pyrite aggregates is consistent with the single-crystal findings, with the exception that {001}<11̄> also appears to be important, although less common than the {001}<100> slip system. The lack of crystal preferred orientation (CPO) development in the polycrystalline pyrite aggregates can be accounted for by the presence of two independent symmetrically equivalent slip systems more than satisfying the von Mises criterion.

The Temperature and Strain Rate Dependence of the Flow Stress in MoSi2 Single Crystals

1993 ◽  
Vol 322 ◽  
Author(s):  
S.A. Maloy ◽  
T.E. Mitchell ◽  
John J. Petrovic ◽  
A.H. Heuer ◽  
J.J. Lewandowski
Keyword(s):  
Flow Stress ◽  
Slip System ◽  
Strain Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Stress Exponent ◽  
Deformation Mechanisms ◽  
Strain Rates ◽  
Jump Test ◽  
Stress And Deformation

AbstractThe temperature dependence of the flow stress and deformation mechanisms of single crystal MoSi2 have been determined for compression along three different orientations, [001], [021] and [771], at two different strain rates, 1 × 10−5/s and 1 × 10−4/s, and at temperatures between 900 and 1600°C. The flow stress along [021] is slightly higher than that along [771] while both orientations gave a much lower flow stress than that along [001]. Along [021], slip occurs on the {110} 1/2<111> slip system between 1000 and 1200°C, while at 1300-1400°C, slip occurs on the {013}<100> slip system. Along [771], deformation occurs by the [001]<100> slip system while cross-slip onto {013} and [011] planes is observed at 1000-1300°C except that slip occurs on the {013{1/2<331> slip system at 1000-1100°C for faster strain rates. Along [001], slip occurs on the {013}1/2<331> system at 900-1100°C while slip is observed on the {011} 1/2<111> system at 1300-1600°C. Strain rate jump tests from 1×10−5/s to 5x10−5/s at 1 100°C revealed a stress exponent of 7 along [771] and 20 along [021], while a rate jump test from lx10−5/s to 2x 10−5/s along [001] at 1400°C gave a stress exponent of 3.9.

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