Pressure-induced solid state phase transitions and plastic deformation in alloys
The analysis of materials under high pressures is both important for understanding astronomical or geophysical processes and for technological applications. For example, new materials with improved properties, such as increased strength , can be created by impact loading.
MD simulations have been used to determine the 3-wave structure of elastic compression, plastic, i.e. permanent deformation, and phase transformation in polycrystalline iron. Understanding this phase transition is important to produce improved materials that are stable under environmental conditions. For this purpose, an interaction potential has been generated which well describes the interplay of transformation and plastic deformation in iron. In this project, the potential described above was coupled with different potentials for the interaction between iron and carbon. The mechanical properties of iron-carbon crystals are investigated under high pressure compression. Thus, the 3-wave structure consisting of elastic and plastic wave and phase transformation can be determined. In agreement with experiments, carbon leads to an increased transition pressure. Currently, we are working in the group to extend these results to carbon-based alloys and high-entropy alloys.
Publication list
- D. Thürmer, O. R. Deluigi, H. M. Urbassek, E. M.Bringa, N. Merkert. Atomistic Simulations of the Shock and Spall Behavior of the Refractory High-Entropy Alloy HfNbTaTiZr. High Entropy Alloys & Materials, DOI: 10.1007/s44210-024-00042-2, 2024.
- D. Thürmer, H.-T. Luu, N. Merkert. Molecular dynamics simulation of shock waves in Fe and Fe–C: Influence of system characteristics. J. Appl. Phys. 135:155901, 2024
- D. Thürmer, N. Gunkelmann. Shock-induced spallation in a nanocrystalline high-entropy alloy: An atomistic study. J. Appl. Phys. 131:065902, 2022.
- D. Thürmer, S. Zhao, O. R. Deluigi, C. Stan, I. A. Alhafez, H. M. Urbassek, M. A. Meyers, E. M.Bringa, N. Gunkelmann. Exceptionally high spallation strength for a high-entropy alloy demonstrated by experiments and simulations. J. Alloys Compd. 895:162567, 2022.
- H.-T. Luu, R. J. Ravelo, M. Rudolph, E. M. Bringa, T. C. Germann, D. Rafaja und N. Gunkelmann, Shock-induced plasticity in nanocrystalline iron: Large-scale molecular dynamics simulations, Phys. Rev. B 102, 020102(R), 2020.
- N. Gunkelmann und M. Merkert, Improved energy minimization of iron carbon systems: On the influence of positioning interstitial atoms, MSMSE 28(4) , 045005, 2020.
- H.-T. Luu und N. Gunkelmann, Pressure-induced phase transformations in Fe-C: Molecular dynamics approach, Comput. Mater. Sci., 162, 295-303, 2019.
- H.-T. Luu, R. G. A. Veiga und N. Gunkelmann, Atomistic Study of the Role of Defects on α --> ε Phase Transformations in Iron under Hydrostatic Compression, Metals 9(10):1040, 2019
