Microstructural evolution and deformation mechanism of the 80 W-20Cu alloy at ultra-high strain rates under explosive loading

The microstructural evolution and deformation mechanism of the 80 W-20Cu alloy at ultra-high strain rates under explosive loading were systematically investigated. During the deformation process, the W skeleton with high strength was fragmented into W particles, and the W particles were slightly elongated. The Cu matrix was severely deformed and significantly contributed to coordinating the deformation of the 80 W-20Cu alloy. Under ultra-high stain rate conditions, the deformation mechanism of the Cu matrix undergoes dynamic recrystallisation, a process in which dislocation movement plays a dominant role instead of twinning. A novel structure of high-density dislocation walls was found in the deformed Cu matrix. Analysis shows that under the conditions of ultra-high strain rate loading, high-density dislocation walls composed of parallel dislocation lines are generated in Cu grains that subsequently turn into large angular boundaries. Large angular boundaries ultimately transform into refined grain boundaries, and thus, grain refinement is accomplished.