Shock compression, melting and impedance mismatch studies in [formula omitted] based on first principles

Abstract

Al-Li alloys have several advantages over conventional Al alloys on account of their properties such as low mass density and high strength. δ′−Al3Li phase is considered to be the most important strengthening phase in Al-Li alloys. In the present study, we predicted the shock induced compression of δ′−Al3Li for the first time. Our simulations indicated that shock induced melting was expected to occur in δ′−Al3Li at ∼80GPa. Hence, structural and mechanical stability of δ′−Al3Li were established up to 80GPa using ab-initio methods. First-principles calculations were done to obtain the parameters required for modelling equation-of-state of Al3Li. Further, impedance mismatch (IM) simulations were performed on bilayer targets (Al3Li-Au and Al-Au). It was observed from the simulations that use of Al3Li instead of Al led to ∼9% higher shock pressure amplification in Au. The ultimate tensile strength at which Al3Li ruptures was estimated and found to be ∼10.57GPa. It was also observed that, Al3Li becomes ductile at high pressures beyond 60GPa. Our study corroborates the use of Al-Li alloys which contain a huge volume fraction of Al3Li phase, as a structural material in place of Al in shock studies.