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Browsing by Author "Nabarro, FRN"

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  • Nabarro, FRN (Pergamon-Elsevier Science Ltd, 1997-08-15)
    The author provides a brief overview of the chemical driving forces for rafting in superalloys. Until recently, all theories of the driving force for rafting have considered the compositions of the two phases to be fixed, ...
  • Nabarro, FRN (Pergamon-Elsevier Science Ltd, 1994-04-15)
    The theory of work hardening in stage IV depends on the relation between the relative misorientation Psi of neighbouring subgrains and the plastic strain gamma (Psi = B gamma exp). The value of the constant B is suggested ...
  • Nabarro, FRN (Minerals Metals Materials Society, 2002-02)
    The creep rate in a land-based power station must be less than 10(-11) s(-1). At these low rates of deformation the transport of matter occurs by the migration of vacancies rather than by the glide of dislocations. A ...
  • Nabarro, FRN (Elsevier Science SA, 2004-12-15)
    Three models of power-law creep are frequently presented. Those of Weertman assume distributed sources of dislocations which spread until they meet dislocations from other sources. They then annihilate by bulk diffusion. ...
  • Nabarro, FRN (Elsevier Science SA, 1997-08-30)
    The origin of the Peierls model and its relation to that of Frenkel and Kontorova are described. Within this model there are three essentially different formulae for the stress required to move a dislocation rigidly through ...
  • Nabarro, FRN (AMER INST physics, 2000-08)
    If a stress sigma is applied to a polycrystal of grain size L, the mode of creep deformation depends on the answers to the following questions: (i) Does sigma exceed the Peierls stress sigma (p); (ii) Does L exceed the ...
  • Nabarro, FRN (Taylor & Francis Ltd, 1996-02)
    Some general theorems, new and old, concerning the behaviour of elastic inclusions and inhomogeneities in bodies without or with external stress, are assembled. The principal new result is that arbitrary external tractions ...
  • Nabarro, FRN; Wilsdorf, DK (Pergamon-Elsevier Science ., 1996-12)
    The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a ...
  • Nabarro, FRN (Taylor & Francis Ltd, 2003)
    The analysis of thermal activation under shear stress in three- and even two-dimensional models presents unresolved problems. The analysis of one-dimensional models presented here may illuminate the study of more realistic ...
  • Makhele-Lekala, L; Luyckx, S; Nabarro, FRN (Elsevier Science Ltd, 2001)
    The Vickers hardness of several well-characterized grades of WC-Co (23 in total) was measured. The mean grain size of these samples ranged from 0.6 to 5.0 mums and the cobalt content from 6 to 50 wt%. An empirical formula ...
  • Nabarro, FRN (Pergamon-Elsevier Science, 1998-11-13)
    This article shows the differences of two-dimensional polycrystal of a material with a rectangular unit cell with lattice spacing b and b (1 + epsilon), subjected to a uniform external stress sigma. Consider a grain in ...
  • Nabarro, FRN (Taylor & Francis Ltd, 1997-03)
    The Peierls stress is the stress required to move a dislocation through a perfect crystal lattice. Theoretical estimates show an exponential dependence on the ratio of the spacing between gliding planes and the unit slip ...
  • Nabarro, FRN; Cress, CM; Kotschy, P (Pergamon-Elsevier Science Ltd, 1996-08)
    Eshelby’s energy-momentum tensor is used to provide an analytical expression for the driving force for rafting in the elastic regime in a super alloy with a high volume fraction of gamma'. The structure is modeled as a ...
  • Nabarro, FRN (Elsevier Science SA, 2001-07-15)
    Under certain conditions, the plastic extension of a sample subjected to a constant stress is to a good approximation proportional to the logarithm of the time. Similarly, if a sample is plastically strained and unloaded, ...
  • Nabarro, FRN (Elsevier Science Ltd, 2000-09)
    The structure and properties of two families of lattice-coherent composites, those based on gamma' Ni3Al and those based on TiA/Ti3Al, are shown to have strong similarities. The coherent system of cubic/tetragonal ...