Modeling High Strain Rate Plasticity in BCC Lead

High-energy lasers have enabled the determination of constitutive properties of metals at very high pressures and strain rates. Here we consider the strength (flow stress) of lead in the high-pressure body-centered cubic (bcc) phase. There were two models of high-strain-rate lead strength available previously. Both models were constructed using data from the low-pressure, face-centered cubic phase of lead. Plasticity in bcc and fcc crystals can be very different. Experiments conducted at the National Ignition Facility have used ramp-compression to drive Rayleigh-Taylor instability and measured the ripple growth to infer lead strength in the bcc phase. We have developed an Improved Steinberg-Guinan model for bcc lead strength [1] using ab initio calculations of the shear modulus at pressure. We compare the predictions of the model with those from the two previous models and results from experiment. We also discuss the effect of alloying.