Activation Energy for Grain Growth of the Isochronally Annealed Ultrafine Grained Magnesium Alloy after Hot Extrusion and Equal-Channel Angular Pressing (EX-ECAP)

• Authors: J. Stráská , J. Stráský , M. Janeček
• Languages of publication: EN

Abstracts

EN

Magnesium alloy AZ31 prepared by hot extrusion and 4 passes of equal-channel angular pressing (EX-ECAP) has ultra-fine grained microstructure with an average grain size of 900 nm. Grain growth is analysed using a general equation for the grain growth and an Arrhenius equation. The calculated value of the activation energy for grain growth differs with the annealing temperature. The fitted value of activation energy for grain growth in the intermediate temperature range (210-400°C) is in accordance with the results of other authors, but it is shown in this study that such value is abnormally low and physically meaningless. More real values of apparent activation energy in this temperature range were calculated from the model assuming a linear increase of activation energy with increasing annealing temperature. Result of this linear model of evolution of activation energy in the temperature range between 210-400°C is expressed by the interval estimation of apparent activation energy values. It is concluded that the evolution of apparent activation energy can be explained by a change in the mechanism underlying the grain boundary migration. In the low temperature range, the grain boundary diffusion is dominant since the material is ultra-fine grained, whereas at higher temperatures, the lattice self-diffusion is more important.

Keywords

EN

62.20.fq; 81.05.Bx; 81.20.Hy; 81.40.Lm; 81.70.Bt

Discipline

• 81.05.Bx: Metals, semimetals, and alloys
• 81.70.Bt: Mechanical testing, impact tests, static and dynamic loads(see also 62.20.M- Structural failure of materials; 46.50.+a Fracture mechanics, fatigue, and cracks)
• 62.20.fq: Plasticity and superplasticity
• 81.20.Hy: Forming; molding, extrusion, etc.[see also, 83.50.Uv Material processing (extension, molding, etc.)]
• 81.40.Lm: Deformation, plasticity, and creep(see also 83.50.-v Deformation and flow in rheology)

• Journal: Acta Physica Polonica A
• Year: 2015
• Volume: 128
• Issue: 4
• Pages: 578-581

Dates

published

2015-10

Contributors

author

J. Stráská

• Department of Physics of Materials, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic

author

J. Stráský

• Department of Physics of Materials, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic

author

M. Janeček

• Department of Physics of Materials, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2, Czech Republic

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Identifiers

DOI

10.12693/APhysPolA.128.578