Extreme rejuvenation of a bulk metallic glass at the nanoscale by swift heavy ion irradiation

Swift heavy ions can be used as a tool to tune material properties by generating high aspect ratio, nanometric
trails of defects, or new disordered phases. This work explores different aspects of using this tool for rejuvenating
and enhancing plasticity in bulk metallic glasses. An amorphous alloy with a nominal composition of Pd40Ni40P20
was irradiated with GeV-accelerated Au ions. Irradiation-induced out-of-plane swelling steps up to approxi-
mately 100 nm in height are measured at the boundary between irradiated and non-irradiated areas. Changes of
the relaxation enthalpy have been investigated using differential scanning calorimetry. Low-temperature heat
capacity measurements substantiate an irradiation-induced increase of the boson peak height with increasing
fluences. Accompanying transport measurements using radioactive Ag atoms as tracer also revealed increased
diffusion rates in the irradiated samples dependent on the total fluence. Nano-indentation measurements show
enhanced plasticity in the ion-irradiated glass which can be correlated with an increased heterogeneity as
indicated by variable resolution fluctuation electron microscopy. ... mehrThe whole volume of the derived data sub-
stantiates a prominent enhancement of the excess volume in the solidified ion tracks and the irradiation-induced
modifications are discussed and analyzed in the framework of strong glass rejuvenation within the nanometric
ion tracks.