Equation of State for Al-Li Alloy

The most materials have the positive strain-rate sensitivity, the yield stresses of which will increase with the strain-rate increasement. However, based on the dynamic experiments we found that the Al-Li alloy has the negative strain-rate sensitivity and the impact ductility. In this paper, by means of the gas gun experiments, the free-surface velocity history and other related parameters are measured, and the D-u Hugoniot curve of Al-Li alloy is obtained. The experiments reveal that under the impact loading the double wave structure similar to that in elastoplastic materials will occur in this strain-rate sensitive material, which shows that our concept about the material of limited negative strain-rate sensitivity is reasonable. Finally, under the hypothesis of weak shocks, we deduced the relationship between the D-u Hugoniot curve and the Murnagham equation, and the parameters of Murnagham equation of Al-Li alloy are obtained based on the experimental data.