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Published July 2020 | Submitted + Supplemental Material
Journal Article Open

Influence of thermomechanical loads on the energetics of precipitation in magnesium aluminum alloys


We use first principles calculations to study the influence of thermomechanical loads on the energetics of precipitation in magnesium-aluminum alloys. Using Density Functional Theory simulations, we present expressions of the energy of magnesium-aluminum binary solid solutions as a function of concentration, strain and temperature. Additionally, from these calculations, we observe an increase in equilibrium volume (and hence the equilibrium lattice constants) with the increase in concentration of magnesium. We also observe an increase in the cohesive energy of solutions with increase in concentration, and also present their dependence on strain. Calculations also show that the formation enthalpy of β phase solutions to be strongly influenced by hydrostatic stress, however the formation enthalpy of α phase solutions remain unaffected by hydrostatic stress. We present an expression of the free energy of any magnesium aluminum solid solution, that takes into account the contributions of strain and temperature. We note that these expressions can serve as input to process models of magnesium-aluminum alloys. We use these expressions to report the influence of strains and temperature on the solubility limits and equilibrium chemical potential in Mg-Al alloys. Finally, we report the influence of thermomechanical loads on the growth of precipitates, where we observe compressive strains along the c axis promotes growth of precipiates with a (0001)_α habit plane, whereas strains along the a and b directions do not influence the growth of precipitates.

Additional Information

© 2020 Acta Materialia Inc. Published by Elsevier Ltd. Received 24 December 2019, Revised 27 February 2020, Accepted 5 March 2020, Available online 23 March 2020. The computations presented here were conducted on the Caltech High Performance Cluster partially supported by a grant from the Gordon and Betty Moore Foundation. Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-12-2-0022. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. The author hereby declare that neither he nor his co-author Swarnava Ghosh have any financial interest in the results described in our manuscript, Influence of thermomechanical loads on the energetics of precipitation in magnesium aluminum alloys.

Attached Files

Submitted - 1912.11434.pdf

Supplemental Material - 1-s2.0-S1359645420301841-mmc1.pdf


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August 19, 2023
October 19, 2023