Dynamic High-temperature Testing of an Iridium Alloy in Compression at High-strain Rates

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In this study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. Appropriate modifications were then made to the current high-temperature Kolsky bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high-strain rates (300-10000s(-1)) and temperatures (750 and 1030 degrees C). The compressive stress-strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.