Influence of Grain Size and Thermo-Mechanical Conditions on the Activation Energy for Super Plastic Flow in Ti-6Al-4V Alloy

Abstract:

The essential objective of this work is to establish the influence of grain size and thermo-mechanical conditions on the activation energy for super plastic flow (Q_SPF) in Ti-6Al-4V alloy by applying the quantum mechanics and relativistic model (QM-RM) proposed by Muñoz-Andrade, in the framework of the unified physics. The QM-RM allows the direct determination of the Q_SPF in advanced materials at instantaneous thermo-mechanical material working conditions. By applying, the QM-RM on the experimental results reported previously by some authors, it is shown for grain size of 6.1μm, that the calculated Q_SPF for grain boundary sliding is about 193 and 178 kJ/mol, at 850°C with an efficiency of power dissipation, η=0.65. These results are in closed agreement with the values of 204 and 174 kJ/mol reported previously for grain boundary self-diffusion energy of α-Ti. Nevertheless, for grain size of 0.6μm the calculated Q_SPF is 142 kJ/mol at 650°C, with an efficiency of power dissipation, η=0.61. As well, in order to understand the phenomenology and mechanics of SPF in Ti-6Al-4V alloy, the variation of the activation energy with the temperature; stress and strain rate is analyzed in association with coupled mechanisms during SPF, such as grain boundary sliding, cooperative grain boundary sliding and self-accommodation process related to the microstructure. In summary, the results of Q_SPF obtained in this work, by the QM-RM are in closed agreement with results reported previously by using the theoretical and conventional methodology set up by Mohamed and Langdon.

• Periodical: Materials Science Forum (Volume 941)
• Pages: 1210-1215
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.1210
• Online since: December 2018
• Authors: Juan Daniel Muñoz-Andrade
• Keywords: Activation Energy, Quantum Mechanics, Special Relativity Theory, Super Plastic Flow, Titanium Alloy, Unification of Physics

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