Melting Temperatures of OFHC Copper under Shock Compression Measured by Optical Radiometry Techniques

Melting temperatures of OFHC (Oxygen-Free High Conductivity) copper at pressures ranging from 110 GPa to 140 GPa were measured on a two-stage light-gas gun by optical radiometry techniques and using LiF single crystal as window, based on such a conclusion that the melting temperatures at the sample/window interface pressure is equal to the release temperature, and close to the interfacial temperature if the OFHC copper sample is initially shocked or released into the region adjacent to the liquidus. The obtained data are consistent with the experimental results of high-pressure sound velocity measurements and theoretical predictions, and the melting behavior of OFHC copper at high pressure can be approximately described with Lindemann melting law. The method for melting temperature measurements we proposed in this paper avoided derivation of Hugoniot temperature, which simplified the determination of melting temperature, and provided a potential approach for melting temperature measurements of metals.