Plastic deformation twinning

A series of events can take place in response to the thermal stresses (/) plastic deformation of the ductile metal matrix (sHp, twinning, cavitation, grain boundary sliding, and/or migration) (2) cracking and failure of the brittle fiber (5) an adverse reaction at the interface and (4) failure of the fiber—matrix interface (17—20). 

This analysis is consistent with the conclusion of Gerk (1977) that the behavior that determines hardness is deformation-hardening not the yield stress. He was one of the first authors to point this out. For other types of materials, it is the maximum stress that the material can bear after deformation (plastic, or that associated with phase transitions in eluding twinning). Hardness is not directly related to the elastic limit, although there is an indirect connection with the offset plastic deformation of metals as demonstrated by Tabor (1951). 

Figure 5.9 Schematic illustration of plastic deformation in single crystals by (a) slip and (b) twinning. From Z. Jastrzebski, The Nature and Properties of Engineering Materials, 2nd ed. Copyright 1976 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

In polymer processing, compaction is an important and necessary step in order to reduce the interparticle, unoccupied spaces and thus eliminate air. It is essential for melting in both single-screw extruders as well as for twin-rotor processors, as we shall see in Chapters 5 and 10. In twin-rotor devices, such as Co-TSEs, for example, the large and repeated deformation of compacted particulates by the kneading elements, which induces large plastic deformation of particulates, is the dominant melting mechanism. 

Twinning, where the crystallographic orientation changes significantly in the region of plastic deformation... 

Fig. 14. Twins produced by plastic deformation and broadened by annealing at 650°C in an imperfect single crystal of a - U grown by progressive phase-change from j3 to a. The bands with different shades correspond to the recovery of the subgrains of the initial crystal. Electroetching reveals small disorientations between the subgrains X150. (D. Calais, P. Lacombe and Mme Simenel, Rev, met., 56, 261 (1959)).

G,28 O. Johari and G. Thomas. The Stereographic Projection and its Applications (New York Interscience, 1969. Vol. HA of Techniques of Metal Research, R. F. Bunshah, ed.). Besides applications to x-ray and electron diffraction patterns, there are treatments of trace analysis, twinning and plastic deformation. Computer... 

Twinning facilitates relaxation of stress by plastic deformation but interaction of twin bands with grain boundaries may initiate cracks. Plasticity of Crl8Re and Cr35Re alloys is sufficient to impeach the formation of such cracks even after 71% deformation at room temperature. 

M.L. Kronberg, Plastic deformation of single crystals of sapphire Basal slip and twinning, Aeta Met. 5, 507-529 (1957). 

The elastic and plastic deformation behavior, including mechanical twinning, of... 

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