Structural phase transformation in bulk single crystal Cu in different orientation under shock loading of different intensities has been investigated in this article. Atomistic simulations, such as, classical molecular dynamics using embedded atom method (EAM) interatomic potential and ab-initio based molecular dynamics simulations, have been carried out to demonstrate FCC-to-BCT phase transformation under shock loading of 〈100〉 oriented bulk single crystal copper. Simulated x-ray diffraction patterns have been utilized to confirm the structural phase transformation before shock-induced melting in Cu(100).
24 January 2017 in Modelling and Simulation in Materials Science and Engineering
Even though there are numerous experiments and molecular dynamic simulations of Cu under shock loading, there appears to be no literature on the evolution of different types of dislocation mechanisms and their mutual interactions during the process of shock loading, which this article addresses through molecular dynamic simulations using the Mishin EAM potential for Cu. Three different directions , , and that have been considered in this article are subjected to shock compression with piston velocities ranging between 0.3–3 km s −1 . The evolution of Hirth locks, Lomer–Cottrell locks, cross-slips, jogs, and dislocation-originated stacking-fault tetrahedra are demonstrated in this article for different direction shock loading of single-crystal Cu.
Non-equilibrium molecular-dynamic simulations were carried out on model three-dimensional nano-void copper material with different idealised pore structure and porosity to highlight differences in response behaviour between them when subjected to various piston velocities simulating planar shock loading of different intensities. This article demonstrates and explains from a mechanistic perspective the differences in response observed with respect to Hugoniot elastic limits, dislocation line and jet formation, void collapse mechanism and hot spot generation, specific volume, partial recrystallisation and temperature evolution in void collapsed regions, shock and particle velocity curves.
Molecular dynamics simulations were carried out using numerous force potentials to investigate the shock induced phenomenon of pure bulk liquid water. Partial phase transition was observed at single shock velocity of 4.0 km/s without requirement of any external nucleators. Change in thermodynamic variables along with radial distribution function plots and spectral analysis revealed for the first time in the literature, within the context of molecular dynamic simulations, the thermodynamic pathway leading to formation of ice VII from liquid water on shock loading. The study also revealed information for the first time in the literature about the statistical time-frame after passage of shock in which ice VII formation can be observed and variations in degree of crystallinity of the sample over the entire simulation time of 100 ns.