MAT Collaboration Meeting 2026

Pd40Ni40P20 bulk metallic glass samples that have been subjected to different relaxation states were investigated by nanoindentation and laser scanning microscopy (LSM) for irradiation effects induced by swift heavy ions. The samples were irradiated with 4.8 MeV/u Xe-ions at the UNILAC accelerator at GSI in Darmstadt. During irradiation, the samples were partially covered with honeycomb- patterned masks to enable direct comparison between irradiated and non-irradiated areas. LSM revealed a distinct swelling step at the mask boundary, whose height increased with ion fluence and varied systematically with the relaxation state of the material. The observed swelling is attributed to ion track formation, where localized melting and rapid re-solidification generates excess volume due to cooling rates exceeding the initial quenching rate. Nanoindentation measurements demonstrated a fluence-dependent decrease in hardness; however, the hardness of irradiated regions consistently remained higher than that of the pristine samples. These findings offer new insight into the structure modification of bulk metallic glasses under medium-mass swift ion irradiation, where elastic collision effects increasingly compete with ion track formation governed by electronic energy-loss processes.