Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Abstract

Pure copper was compressed at high strain rates (over similar to 3 x 10(3) s(-1)) under liquid nitrogen. This deformation resulted in bi-modal microstructures of ultrafine grains and abnormally grown micro grains, and in greater hardness (by similar to 30 Hv) than room-temperature, dynamically deformed copper. This bi-modal microstructure is attributable to partial recrystallization at room temperature, activated by high-energy states and by twins generated at high Zener-Hollomon parameter conditions. This result demonstrates a new approach for producing bi-modally structured materials.