  The atomistic structure of metallic glasses is closely related to properties
such as strength and ductility. Here, Ni1-xBx metallic glass nanoparticles of
two different sizes are compressed under quasi-hydrostatic high-pressure
conditions in order to understand structural changes under stress. The
structural changes in the nanoparticles were tracked using in situ
high-pressure X-ray diffraction (XRD). The ambient pressure pair-distribution
functions generated from XRD showed that the smaller sized nanoparticles had a
more compact amorphous structure with lower coordination number. XRD showed
that the amorphous structure was stable up to the maximum pressures achieved.
The bulk modulus of the smaller and larger sized nanoparticles was found to be
208 GPa and 178 GPa, respectively. This size-dependent high-pressure behavior
was related to compositional differences between the nanoparticles. These
results show that Ni1-xBx metallic glass nanoparticles are highly stable under
pressure, which could enable their use as inclusions in metal or ceramic matrix
composites.
