Experimental and theoretical examination of shock-compressed copper through the fcc to bcc to melt phase transitions

Recent studies show a face-centered cubic (fcc) to body-centered cubic (bcc) transformation along the shock Hugoniot for several metals (i.e., Cu, Au, and Ag). Here, we combine laser-shock compression of Cu foils on nanosecond timescales with in situ x-ray diffraction (XRD) to examine the microstructural changes with stress. We study the fcc phase and the phase transition from fcc to bcc (pressures greater than 180 GPa). Textural analysis of the azimuthal intensities from the XRD images is consistent with transformation into the bcc phase through the Pitsch-distortion mechanism. We use embedded atom model molecular dynamics simulations to determine the stability of the bcc phase in pressure-temperature space. Our results indicate that the bcc phase is stabilized only at high temperatures and remains stable at pressures greater than 500 GPa.

Automated summary

Recent studies have shown that several metals undergo a transformation from face-centered cubic (fcc) to body-centered cubic (bcc) structure during shock compression. Experiments and simulations have revealed that this fcc to bcc transition occurs at high pressures and temperatures, and the bcc structure remains stable at even higher pressures.