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| Frank–Read source | |
|---|---|
| Name | Frank–Read source |
| Caption | Schematic of dislocation loop nucleation by a pinned segment under shear |
| Field | Materials science, Solid state physics, Metallurgy |
| Discoverers | Frederick C. Frank; Thornton Read |
| Year | 1950 |
Frank–Read source The Frank–Read source is a fundamental mechanism for dislocation multiplication in crystalline solids, first proposed by Frederick C. Frank and Thornton Read in 1950. It provides a microscopic explanation for strain hardening and plastic flow in metals and alloys studied by institutions such as Bell Labs, Harvard University, and Massachusetts Institute of Technology. The mechanism links observations from experiments at Los Alamos National Laboratory, Oak Ridge National Laboratory, and Lawrence Berkeley National Laboratory to theories developed at University of Cambridge and ETH Zurich.
The Frank–Read source concept explains how a pinned dislocation segment in a crystal can bow out and emit dislocation loops under applied shear stress, connecting early work by Vito Volterra and later developments by researchers at Imperial College London and California Institute of Technology. It bridges theoretical frameworks from Paul Dirac-era elasticity and later computational advances by groups at Sandia National Laboratories and Argonne National Laboratory. The mechanism underpins explanations for phenomena reported in studies at Max Planck Society, Rutherford Appleton Laboratory, and Columbia University.
Mechanistically, a pinned dislocation segment on a slip plane under shear stress bows out due to Peach–Koehler forces until it forms a loop and leaves behind the original pinned segment, a process analyzed with concepts from A. A. Griffith fracture theory and models inspired by Ludwig Prandtl's work. The energetics involve line tension comparable to analyses from Cauchy, while the kinetics relate to observations by G. I. Taylor on slip and by Alan Cottrell on climb and glide. The process is influenced by obstacles like precipitates studied at Bell Labs Materials Research Laboratory and solute atoms characterized in work from DuPont and General Electric Research Laboratory.
Mathematical models treat the pinned segment as an elastic curve subject to boundary conditions, invoking equations similar to those used at Princeton University and Stanford University in continuum mechanics. Numerical simulations using dislocation dynamics codes developed at Lawrence Livermore National Laboratory and multiscale approaches from Northwestern University and Brown University couple molecular dynamics methods pioneered at Scripps Research and finite element methods from ETH Zurich. Models incorporate material parameters measured at National Institute of Standards and Technology and computational techniques endorsed by Oak Ridge National Laboratory and Argonne National Laboratory.
Direct and indirect evidence comes from transmission electron microscopy studies at University of Cambridge, in situ deformation experiments at Harvard University, and high-resolution microscopy at University of Oxford. Classic confirmation was provided by experiments at Bell Labs and later by synchrotron-based techniques at European Synchrotron Radiation Facility and Advanced Photon Source. Observations correlate with alloy behavior characterized by United States Steel Corporation and microstructural control strategies developed at Los Alamos National Laboratory.
The Frank–Read mechanism is central to strain hardening models used by General Motors and Toyota in forming operations and informs constitutive laws adopted at Sandia National Laboratories. It explains work hardening stages discussed in textbooks from Cambridge University Press and material selection criteria used by Boeing and Rolls-Royce Holdings. Its influence extends to design of high-strength steels by ArcelorMittal and superalloys for Pratt & Whitney engines.
Related mechanisms include sources such as single-arm sources observed in irradiated materials studied at CERN, jog and kink formation described by Nevill Mott, and cross-slip phenomena analyzed by John H. Conway. Irradiation-induced loops and void swelling investigated at Idaho National Laboratory and climb-assisted mechanisms examined at Argonne National Laboratory provide complementary multiplication pathways. The Frank–Read concept also connects to sessile and glissile dislocation behaviors documented at Kurchatov Institute and Brookhaven National Laboratory.
Proposed by Frederick C. Frank and Thornton Read in 1950, the mechanism was rapidly integrated into the work of G. I. Taylor, Alan Cottrell, and Nevill Mott, shaping postwar metallurgy programs at Imperial College London and Massachusetts Institute of Technology. Its conceptual clarity influenced computational efforts at Lawrence Berkeley National Laboratory and modern materials design initiatives at Materials Project and Oregon State University. The Frank–Read source remains a cornerstone of dislocation theory and continues to inform research at Max Planck Institute for Iron Research and industrial programs at ArcelorMittal and BASF.
Category:Dislocations Category:Materials science