Self-diffusion of lead in oriented grain-boundaries

Okkerse, B.; Tiedema, T. J.; Burgers, W. G.

doi:10.1016/0001-6160(55)90074-2

Cited by 24 publications

(3 citation statements)

References 11 publications

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“…Consequently, in these thermo mechanical conditions change the amplitude of vibration of the atoms and their frequency due to the amount of vibration energy absorbed and related with the variety of disorders occurring during such irreversible deformation process [3,[8][9]. The activation energy values reported in this work, there are in a very closed agreement with the activation energy of 65.7 kJ/mol for grain boundary diffusion reported previously by Okkerse [10], and also with the values of 45 -75 kJ/mol reported by Avery and Stuarts for superplastic flow in the Pb-Sn eutectic alloy [11]. In the same way with the activation energy value of 56.9 kJ/mol, reported by Mohamed and Langdon [12] by a using a conventional methodology [13][14].…”

Section: Resultssupporting

confidence: 83%

Systematic Study of Polycrystalline Flow during <i>In Situ</i> Tension Test by SEM of Pb-50%Sn at Room Temperature

López-Ramírez

Muñoz-Andrade

Garfias-García³

et al. 2014

MSF

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Microstructural evolution during in situ tension test at constant crosshead velocity of 0.38 mm/min, at room temperature of polycrystalline Pb-50%Sn alloy are reported. Direct observation during four steps of deformation, with a total deformation (εT) of 0.684, allows establish that the trajectories of grains during irreversible deformation process obey a sigmoidal motion. Such behaviour is related with dynamic recrystallization phenomenology and associated with grain boundary sliding between neighbouring grains and subsequent cavitation in order to allow emerging grains from the inner volume to free surface of Pb-50%Sn, as the main mechanisms of superplastic flow. The curve of true stress versus true deformation presented several fluctuations during irreversible deformation process in a similar way of the Portevin Le Chatelier effect. Also is observed in the early steps of plastic flow, hardening deformation, up to 27 MPa associated with the maximum stress. The activation energy values for polycrystalline flow, calculated in this work are between 67.5 to 68.07 kJ/mol and there are in a closed agreement with the activation energy of 65.7 kJ/mol, for grain boundary diffusion.

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Section: Resultssupporting

confidence: 83%

Systematic Study of Polycrystalline Flow during <i>In Situ</i> Tension Test by SEM of Pb-50%Sn at Room Temperature

López-Ramírez

Muñoz-Andrade

Garfias-García³

et al. 2014

MSF

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“…The testing temperatures in this work are in the range of 0.57-0.67 T m , which are lower than the temperatures used by other research groups [13,23] in their creep study of Pb. For high punching stresses and I = 0 A, the activation energy for the rate process is 63.5 kJ/mol, compatible to the activation energy of 65.6 kJ/mol for grain boundary diffusion in Pb [26]. This result suggests that the grain boundary sliding is likely the dominant rate process for the impression creep of Pb at high punching stresses.…”

Section: Apparent Activation Energysupporting

confidence: 57%

Effect of electric current on the creep deformation of lead

Chen

Yang

2011

Materials Science and Engineering: A

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“…In the case of the glass model advocated here, l would be simply 2 6 since there is no core. Since DB is considerably larger than D, (e. g. D,/D, = 6.6 X 103 for lead at its melting point [IO], [20]) this permits simplification to the form which is of course again reminiscent of the Stokes-Einstein and Nabarro-Herring equations, except for the final stress-dependent term. Regarding the latter, one notes that in metals r is usually of the order of 100 ergs cm-2 while l in the present model is of the order of 2 X 10-7 cm.…”

Section: Superplasticity Of Certain Alloy Polycrys-tals Diffusion-acmentioning

confidence: 99%

A Unified Theory of Melting Crystallization and Glass Formation

et al. 1975

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In recent years, dislocations have been involved in theories of melting, in models of the liquid state, and in calculations of the viscosity of glasses. Particularly noteworthy are the Mott-Gurney model of a liquid as a polycrystal with a grain size (i. e. a dislocation network size) of near-atomic dimensions, and the demonstration by Kotze and Kuhlmann-Wilsdorf that the solid-liquid interfacial energy is proportional to the grain boundary energy for a number of elements. These developments suggest the possibility of a relatively simple picture of crystallization and glass formation. In the liquid state dislocations, at the saturation density, are in constant motion and the microscopic grain boundary structure that they form is constantly changing due to dislocation-dislocation interaction. As the liquid is cooled below the melting point the free energy favors the crystalline form and grains larger than the critical nucleation size at any given temperature will grow at the expense of the surrounding grains. If this process does not occur the dislocations will remain and a glass will be formed. Just which of these alternatives will actually be observed for a given material will depend especially on the amount of dislocation motion that can take place during the critical period when nucleation and growth becomes favored thermodynamically. Thus the glassy form will have a better chance of being formed if either the liquid is particularly viscous or if the cooling rate is particularly rapid

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Self-diffusion of lead in oriented grain-boundaries

Cited by 24 publications

References 11 publications

Systematic Study of Polycrystalline Flow during <i>In Situ</i> Tension Test by SEM of Pb-50%Sn at Room Temperature

Systematic Study of Polycrystalline Flow during <i>In Situ</i> Tension Test by SEM of Pb-50%Sn at Room Temperature

Effect of electric current on the creep deformation of lead

A Unified Theory of Melting Crystallization and Glass Formation

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