摘要:

AbstractThe character of collective motion of the point defects and dislocations of various types determines the mode of plastic deformation and of fracture as its final stage. The concepts of the translational and rotational modes appeared at an early stage in the study of the mechanisms of plastic deformation in crystals and have undergone substantial evolution in connection with the development of methods for the direct observation of lattice defects. As a rule, different modes, e.g. diffusion and dislocation plasticity, translations and rotations, slip and twinning, plasticity and fracture, etc. are interrelated. The conditions for the loss of stability in plastic deformation and fracture are discussed. The rotational modes of plastic deformation are shown to be a consequence of the translational ones. The disclination modes are demonstrated to result from a simplified description of the dislocation kinetics.

ISSN:0232-1300    

DOI:10.1002/crat.2170190602

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractWith the use of the anisotropic theory of elasticity the energies and the force‐distance profiles for the interaction of various types of straight dislocations with point defects of intrusion (atoms of N, C or O) and of replacement in BCC metals with a different degree of elastic anisotropy (Nb, V, Ta, α‐Fe) have been calculated. The calculated force‐distance profiles in most cases are not centrally symmetric, that leads up to a gliding asymmetry at the direct and reverse directions of dislocation motion. The crystal elastic anisotropy can change the relative mobility of dislocations of various types and accounts for a number of experimentally observed peculiarities of BCC metals stress‐strain pr

ISSN:0232-1300    

DOI:10.1002/crat.2170190603

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractAn analysis has been carried out of the motion of a pair of sign‐similar edge dislocations under a constant shear stress in a simplest nonuniform field of internal stresses τiwith a constant gradient. The influence is shown of the dislocation interaction and τion the activation „volume”︁ of the average velocity of a dislocation pair, which is measured by the flow stress relaxation. The experimentally revealed anomalies of the activation „volume”︁ measured by the flow stress relaxation are regarded as corroborating the analysis and as manifestations of the collective effects of the elastic interaction of sign‐similar mo

ISSN:0232-1300    

DOI:10.1002/crat.2170190604

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170190605

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe rearrangement of the force of dynamic dragging of a dislocation due to its elastic interactio in with impurity atoms is analysed. The collisions of a moving dislocation with impurities excite additional vibrations of a dislocation line. Such vibrations lead to the appearance of extra parts to dissipative function and effective friction force of a dislocation which depend on location and concentration of impurities. This effect is one of the reasons of the influence of impurities observed in the experiments on the dynamic branch of the moving dislocation curve.

ISSN:0232-1300    

DOI:10.1002/crat.2170190606

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe paper is concerned with the formation of a dislocation structure due the thermal stresses in shaped single crystals with different degree of anisotropy grown by Stepanov's method. The calculation of root‐mean‐square tangential stresses allows to determine the regions in which the plastic deformation may occur. Analysis of thermal stresses in separate slip systems permits to explaine the slipe band distribution in shaped single cryst

ISSN:0232-1300    

DOI:10.1002/crat.2170190607

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170190608

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractHigh purity iron single crystals were deformed in tension in the temperature range 4.2 to 473 K. Work‐hardening characteristics were determined and the plastic behaviour in dependence on temperature, strain rate and crystal orientation isz discussed. The transition temperature between low‐temperature and intermediate‐temperature deformation regimes was found to be ≅ 250 K, the critical temperature estimated from the temperature dependence of the critical resolved shear stress is ≅ 380 K. A hump on the temperature dependence of the critical resolved shear stress was observed in the vicinity of 250 K. These observations are qualitatively explained by special mobilities of dislocations in b.c.c

ISSN:0232-1300    

DOI:10.1002/crat.2170190609

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170190610

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractSlip traces were studied on high purity iron single crystals after deformation in tension in the temperature range from 4.2 to 473 K (the same crystals were used for the work‐hardening study described in Part I of this paper). By evaluation of Nomarski interference contrast and by method of repolishing of the surface before incremental loading detailed quantitative information was obtained about slip line pattern in various work‐hardening stages. An improved model of slip processes in stage III of the work‐hardening curve is pres

ISSN:0232-1300    

DOI:10.1002/crat.2170190611

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY