Mechanical and Microstructural Changes in Cu Single-Turn Coils Revealing the Effect of High-Speed Pressurization, Deformation and Heating During Megagauss Field Generation

This study examines the microstructural changes in copper single-turn coils (STC) subjected to intense magnetic pressure during field generation. Three coil types were analyzed: “raw coils” (undeformed reference), “intermediate field coils” (subjected to non-destructive magnetic fields), and “maximum field coils” (destroyed during high-field generation). Vickers microhardness measurements across conductor cross-sections revealed significant local variations ranging from softening to work hardening (∼135 HV0.1) depending on the position and magnetic exposure. The results exhibit good agreement between local microhardness measurements and simulated thermal-mechanical conditions, highlighting the interplay between softening effects due to exposure to high temperatures (∼2500 K) and work hardening due to extreme magnetic pressures (∼10 GPa) occurring on microsecond timescale.