The role of dislocations in the flow stress grain size relationships
01 May 1970-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science (Springer New York)-Vol. 1, Iss: 5, pp 1145-1159
TL;DR: In this article, the authors reviewed the effects of pile ups of dislocations on the relation between yield or flow stress and grain size, and some non-pileup theories of yielding are critically reviewed.
Abstract: Calculations involving pile ups of dislocations, both analytical and numerical, using either discrete dislocations or continuous distribution of dislocations of infinitesimal Burgers vectors, are reviewed in the light of their effects on the relation between yield or flow stress and grain size. The limitations of the pileup models are discussed and some nonpileup theories of yielding are critically reviewed also. More critical experiments are still needed to reveal the fundamental mechanicm of yielding.
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TL;DR: In this paper, the authors present a review of recent developments in the field of deformation behavior of high manganese face-centered cubic γ-Fe alloys, referred to as twinning-induced plasticity, or TWIP, steels.
884 citations
TL;DR: In this paper, the current knowledge on dislocation types and slip systems, the development of deformation substructures, factors controlling the mobility and multiplication of dislocations, interface related plasticity, solid solution and precipitate strengthening mechanisms as well as microscopic aspects of creep and fracture are addressed.
Abstract: During the past decade considerable research efforts have been directed towards achieving balanced engineering properties of two-phase γ-titanium aluminide alloys for future applications as structural materials. For optimization of mechanical properties such as yield and creep strengths, tensile ductility and fracture resistance, a basic understanding of the temperature dependent micromechanisms of plasticity and fracture, and their interplay with various microstructural constituents is required. In this review article, the current knowledge on dislocation types and slip systems, the development of deformation substructures, factors controlling the mobility and multiplication of dislocations, interface related plasticity, solid solution and precipitate strengthening mechanisms as well as microscopic aspects of creep and fracture will be addressed. These topics will be related to specific microstructures and associated engineering properties.
633 citations
01 Dec 1972
TL;DR: The effect of interfaces on mechanical properties is considered in this paper, with emphasis on dislocation mechanisms and the atomic scale structure of boundaries, and Elastic and plastic compatibilities at boundaries are treated.
Abstract: The effect of interfaces on mechanical properties is considered. Elastic and plastic compatibilities at boundaries are treated. Specific influences at both low and high temperatures are discussed, with emphasis on dislocation mechanisms and the atomic scale structure of boundaries.
562 citations
TL;DR: In this paper, the authors gather the grain-size strengthening data from the Hall-Petch studies on pure metals and use this aggregated data to calculate best estimates of these metals' Hall-petch parameters.
Abstract: Refining a metal’s grain size can result in dramatic increases in strength, and the magnitude of this strengthening increment can be estimated using the Hall–Petch equation. Since the Hall–Petch equation was proposed, there have been many experimental studies supporting its applicability to pure metals, intermetallics and multi-phase alloys. In this article, we gather the grain-size strengthening data from the Hall–Petch studies on pure metals and use this aggregated data to calculate best estimates of these metals’ Hall–Petch parameters. We also use this aggregated data to re-evaluate the various models developed to physically support the Hall–Petch scaling.
523 citations
References
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Book•
01 Jan 1968
TL;DR: Dislocations in Isotropic Continua: Effects of Crystal Structure on Dislocations and Dislocation-Point-Defect Interactions at Finite temperatures.
Abstract: Dislocations in Isotropic Continua. Effects of Crystal Structure on Dislocations. Dislocation-Point-Defect Interactions at Finite Temperatures. Groups of Dislocations. Appendixes. Author and Subject Indexes.
10,220 citations
01 Sep 1951
TL;DR: In this paper, an attempt is made to explain the observed phenomena in the yielding and ageing of mild steel, described in two previous papers, in the general terms of a grain-boundary theory.
Abstract: An attempt is made here to explain the observed phenomena in the yielding and ageing of mild steel, described in two previous papers, in the general terms of a grain-boundary theory. On this hypothesis, a satisfactory explanation of the variation of the lower yield point with grain size may be developed. It is shown that strain-ageing must involve two processes: a healing of the grain-boundary films, coupled with a hardening in the grains themselves. A discussion of the possible nature of the grain-boundary film is also undertaken.
5,893 citations
TL;DR: In this paper, the authors measured the velocities of individual dislocations in LiF, covering a range of twelve orders of magnitude in velocity, from 10−7 cm/sec to 105cm/sec.
Abstract: Velocities of individual dislocations have been measured in LiF, covering a range of twelve orders of magnitude in velocity, from 10−7 cm/sec to 105 cm/sec. The velocity is extremely sensitive to applied stress at low velocities, and for each crystal there exists a minimum stress for dislocation motion, below which dislocations do not move. The edge components of dislocation loops move considerably faster than the screw components. The upper limit for dislocation velocity appears to be the velocity of sound in the crystal. The effects of temperature, impurities, and radiation damage on dislocation velocity are described. These variables affect the dynamic resistance to motion encountered by a moving glide dislocation.The growth of total dislocation density, the growth of individual glide bands, and the distribution of glide dislocations during plastic deformation are described.The yield stress of LiF is determined by the resistance to motion encountered by a glide dislocation in moving through an otherwis...
1,345 citations