Equation of state measurements of materials using a three-stage gun to impact velocities of 11 km/s

Results of an experimental series performed utilizing a three-stage gun to obtain precise material property equation of state (EOS) data for a titanium alloy (Ti6-A1-4V) at extreme pressure states that are not currently attainable using conventional two-stage light-gas gun technology is reported herein. What is new is the technique being implemented for use at engagement velocities exceeding 11 km/s. Shock-velocity in the target is being determined using 100 gm diameter fiber-optic pins and measuring shock transit times over a known distance between two parallel planes. These fiber-optic pins also indicate that the flyer-plate bow and tilt is comparable to two-stage light-gas gun technology. The thermodynamic state of the flyer plate prior to impact has also been determined both experimentally and calculationally. In particular, the temperature, and hence the density of the flyer-plate is also well known prior to impact. Results of these studies indicate that accurate Hugoniot information can be obtained using the three-stage light gas gun. This new test-methodology has extended the EOS of Ti6-A1-4V titanium alloy to stresses up to approximately 250 GPa. (C) 2001 Elsevier Science Ltd. All rights reserved.