ORIENTATION DEPENDENCE OF YIELD IN BODY-CENTERED CUBIC METALS

1967 ◽  
Vol 45 (2) ◽  
pp. 1091-1099 ◽  
Author(s):  
D. Hull ◽  
J. F. Byron ◽  
F. W. Noble
Keyword(s):  
Shear Stress ◽  
Deformation Behavior ◽  
Orientation Dependence ◽  
Compressive Deformation ◽  
Slip Systems ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
The Asymmetry ◽  
Critical Resolved Shear Stress ◽  
And Tungsten

Recent observations relating to the critical resolved shear stress for slip in tantalum and tungsten are reported. The results of tensile and compressive deformation are discussed in terms of the operative slip systems and the possible asymmetry of {112} [Formula: see text] slip. It is concluded that the asymmetry hypothesis is unable to account satisfactorily for anomalies in the deformation behavior of these materials.

The Orientation Dependence of Work?Hardening in Crystals of Face-centred Cubic Metals

1960 ◽  
Vol 13 (2) ◽  
pp. 316 ◽  
Author(s):  
LM Clarebrough ◽  
ME Hargreaves
Keyword(s):  
Shear Stress ◽  
Slip Plane ◽  
Work Hardening ◽  
Orientation Dependence ◽  
Slip Systems ◽  
Deformation Bands ◽  
Secondary Slip ◽  
Cubic Metals ◽  
Primary Slip Plane

It is shown that the principal features of the observed orientation dependence of work-hardening can be accounted for in terms of the likelihood of formation. Of Lomer-Cottrell sessile dislocations in two directions in tb" primary slip plane. This is deduced from the known variation of resolved shear stress with orientation, for the possible secondary slip systems, and metallographic observations of slip and deformation bands.

Plastic Deformation of Mo(Si,Al)2 Single Crystals with the C40 Structure

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Moriwaki ◽  
K. Ito ◽  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
Single Crystals ◽  
Deformation Behavior ◽  
Basal Slip ◽  
Room Temperature ◽  
Slip Systems ◽  
Temperature Range ◽  
Al Content ◽  
Partial Dislocations ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

ABSTRACTThe deformation behavior of single crystals of Mo(Si,Al)2 with the C40 structure has been studied as a function of crystal orientation and Al content in the temperature range from room temperature to 1500°C in compression. Plastic flow is possible only above 1100°C for orientations where slip along <1120> on (0001) is operative and no other slip systems are observed over whole temperature range investigated. The critical resolved shear stress for basal slip decreases rapidly with increasing temperature and the Schmid law is valid. Basal slip appears to occur through a synchroshear mechanism, in which a-dislocations (b=1/3<1120>) dissociate into two synchro-partial dislocations with the identical Burgers vector(b*1/6<1120>) and each synchro-partial further dissociates into two partials on two adjacent planes.

Effect of Temperature and Crystal Orientation on the Plasticity (SLIP) Evolution in Single Crystal Nickel Base Superalloy Notched Specimens

2007 ◽  
Author(s):  
Shadab Siddiqui ◽  
Nagaraj K. Arakere ◽  
Fereshteh Ebrahimi
Keyword(s):  
Shear Stress ◽  
Single Crystal ◽  
Element Model ◽  
Effect Of Temperature ◽  
Nickel Base Superalloy ◽  
Shear Stresses ◽  
Slip Systems ◽  
Slip Planes ◽  
Nickel Base ◽  
Critical Resolved Shear Stress

A comprehensive numerical investigation of plasticity (slip) evolution near notches was conducted at 28°C and 927°C, for two crystallographic orientations of double-notched single crystal nickel base superalloys (SCNBS) specimens. The two specimens have a common loading orientation of &lt;001&gt; and have notches parallel to the &lt;010&gt; (specimen I) and &lt;110&gt; (specimen II) orientation, respectively. A three dimensional anisotropic linear elastic finite element model was employed to calculate the stress field near the notch of these samples. Resolved shear stress values were obtained near the notch for the primary octahedral slip systems ({111} &lt;110&gt;) and cube slip systems ({100} &lt;110&gt;). The effect of temperature was incorporated in the model as changes in the elastic modulus values and the critical resolved shear stress (CRSS). The results suggest that the number of dominant slip systems (slip systems with the highest resolved shear stress) and the size and the shape of the plastic zones around the notch are both functions of the orientation as well as the test temperature. A comparison between the absolute values of resolved shear stresses near the notch at 28°C and 927°C on the {111} slip planes revealed that the plastic zone size and the number of activated dominant slip systems are not significantly affected by the temperature dependency of the elastic properties of the SCNBS, but rather by the change in critical resolved shear stress of this material with temperature. The load required to initiate slip was found to be lower in specimen II than in specimen I at both temperatures. Furthermore, at 927°C the maximum resolved shear stress (RSS) on the notch surface was found to be greater on the {100} slip planes as compared with the {111} slip planes in both specimens. The results from this study will be helpful in understanding the slip evolution in SCNBS at high temperatures.

Plastic Deformations in L10-Ordered Single Crystals with their c/a Ratios Less than Unity

2007 ◽  
Vol 561-565 ◽  
pp. 459-462
Author(s):  
Katsushi Tanaka ◽  
Hiromitsu Ide ◽  
Yoshinori Sumi ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Shear Stress ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
The Other ◽  
Compressive Deformation ◽  
Positive Temperature ◽  
Plastic Deformations ◽  
Temperature Range ◽  
Critical Resolved Shear Stress

Compressive deformation of L10-ordered single crystals of FePd whose c/a ratio less than unity have been investigated from room temperature to 823 K. The results show that the critical resolved shear stress (CRSS) for octahedral glide of ordinary dislocations is smaller than that of super-lattice dislocations in all the temperature range investigated, that is the opposite sense to the case of Ti-56 mol% Al. The CRSS for ordinary dislocations virtually independent to the temperature. On the other hand, the CRSS for super dislocations exhibits a weak positive temperature dependence from room temperature up to 573 K and decreases in higher temperatures.

Dislocation Configurations in the γ’ Phase Ni3(AlTi)

1968 ◽  
Vol 26 ◽  
pp. 258-259
Author(s):  
P. H. Thornton ◽  
R. G. Davies
Keyword(s):  
Shear Stress ◽  
Slip Plane ◽  
Wide Temperature Range ◽  
Deformation Behavior ◽  
Slip Mode ◽  
Screw Dislocations ◽  
Temperature Range ◽  
Octahedral Slip ◽  
Critical Resolved Shear Stress

The γ’ phase Ni3Al, as with all f.c.c. metals and also the isomorphous phase CU3Au, deforms by octahedral slip over a wide temperature range. However, in contrast to these other materials cube slip can also occur in γ'. This extra slip mode, which is very unusual in metals, has been observed to operate at temperatures near 800°C. In the present study of the deformation behavior of the γ' phase Ni3(AlTi), the critical resolved shear stress for cube slip was found to become equal to that of octahedral slip at 400°C approximately and was less than that of octahedral slip at 700°C.An examination of slip plane sections of <100> oriented crystals of Ni3(AlTi), in which deformation is restricted to the ﹛111﹜ mode, revealed mainly screw dislocations in samples deformed at temperatures between 25°C and 750°C. At the lower temperatures, the screw dislocations were straight (Fig. 1) whereas at the higher temperatures the dislocations were more heavily jogged (Fig. 2). In contrast, slip plane sections taken from crystals which could deform by cube slip showed both edge and screw dislocations (Fig. 3).

Modeling of Orientation Dependence of Critical Resolved Shear Stress and Deformation Mechanisms on Yield Point of Austenitic Stainless Steels Hardened by Interstitial and Substitution Atoms

2014 ◽  
Vol 1013 ◽  
pp. 264-271
Author(s):  
Olga Ivanova ◽  
Irina Kireeva ◽  
Yuri Chumlyakov
Keyword(s):  
Shear Stress ◽  
Yield Point ◽  
Partial Dislocation ◽  
Tetrahedral Site ◽  
Orientation Dependence ◽  
Deformation Mechanisms ◽  
Octahedral Interstice ◽  
Dislocation Model ◽  
Critical Resolved Shear Stress ◽  
Extended Dislocation

The proposed dislocation model describes the orientation dependence of the critical resolved shear stress (CRSS) and deformation mechanisms on the yield point in single crystals of austenitic stainless steel with nitrogen impurities. The model takes into account the following: the change of the interstitial atom position in the lattice from octahedral interstice to tetrahedral site owing to passage of a leading Shockley’s partial dislocation; the change in the separation width between two partial dislocation in external stress field; the relationship between the width of the extended dislocation and the elastic interaction of the extended dislocation with the impurity atoms.

Strengthening effect of twin boundaries in bcc crystal evaluated through a micro-bending test

2011 ◽  
Vol 1297 ◽  
Author(s):  
Yuki Karasawa ◽  
Tso-Fu Mark Chang ◽  
Akinobu Shibata ◽  
Masato Sone
Keyword(s):  
Shear Stress ◽  
Type Specimen ◽  
Bending Test ◽  
Displacement Curve ◽  
Strengthening Effect ◽  
Body Centered Cubic ◽  
Twin Boundaries ◽  
Bending Deformation ◽  
Nano Scale ◽  
Critical Resolved Shear Stress

ABSTRACTIn the present study, the strengthening effect of nano-scale twins in body-centered cubic (bcc) crystal was evaluated using micro-sized cantilever type specimen which contained the nanotwinned region (midrib) in ferrous lenticular martensite. The SEM observations of the micro-sized specimen after bending deformation indicated that midrib can act as barriers against dislocations, resulting in slip localization and non-localization across midrib. The load-displacement curve obtained by bending test showed that twin boundaries significantly enhance the critical resolved shear stress of bcc.

THE DEFORMATION OF NIOBIUM SINGLE CRYSTALS

1967 ◽  
Vol 45 (2) ◽  
pp. 607-629 ◽  
Author(s):  
R. A. Foxall ◽  
M. S. Duesbery ◽  
P. B. Hirsch
Keyword(s):  
Shear Stress ◽  
Single Crystals ◽  
High Vacuum ◽  
Three Dimensional ◽  
Orientation Dependence ◽  
Ultra High Vacuum ◽  
Text Type ◽  
Dislocation Arrays ◽  
Critical Resolved Shear Stress ◽  
Twist Boundaries

Various orientations of single crystals of niobium, purified by ultra-high vacuum annealing, have been tested in compression at 295 °K and in tension at temperatures between 77 °K and 295 °K. The shear stress – shear strain curves show three-stage hardening in a manner similar to f.c.c. crystals. Analysis of the orientation dependence of the operative slip system suggests an asymmetry in the critical resolved shear stress for slip on {112} planes which increases with decreasing temperature. Explanations for this in terms of the various ways in which a [Formula: see text] type screw dislocation can dissociate have been proposed. It is found that dissociation on two {112} planes or composite dissociation on {110} and {112} planes leads to a satisfactory qualitative explanation of the experimental results.The dislocation distribution occurring as a function of strain has been studied for crystals of a single glide orientation deformed in tension at 295 °K. [Formula: see text] sections from crystals deformed into stage I contain clusters of primary edge dipoles. The density of secondary dislocations is low (~10%). Sections from crystals deformed into stage II were chosen such that the three-dimensional nature of the dislocation arrays could be investigated. The distribution shows strong similarities to those observed in copper crystals (Steeds 1966), i.e. edge multipole walls, tilt and twist boundaries. The density of secondary dislocations is high, being of the same order as the primary density.

Investigation of active slip-systems in some body-centered cubic metals

2011 ◽  
Vol 46 (11) ◽  
pp. 3812-3821 ◽  
Author(s):  
Dilawar Ali ◽  
Nasreen Mushtaq ◽  
M. Z. Butt
Keyword(s):  
Slip Systems ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Active Slip
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