Tuning mechanics of metallic glasses via in silico microalloying

Ductilizing amorphous metals without sacrificing strength is challenging due to unclear plasticity carriers. This study attempts to mimic the microalloying strategy of physical metallurgy in computer simulations by selectively pinning a small fraction of typical atoms in metallic glass, which is targeted to efficiently optimize the mechanical properties. We found that pinning atoms with high participation in the low-frequency vibrational modes are more effective in strengthening, attributing to a mechanism of scale-dependent pinning effect. By pinning only 2 % atoms in the unstable glassy samples, one can achieve shear modulus comparable to samples prepared with cooling rates that are eight orders of magnitude slower, highlighting the validity of microalloying over thermal treatment. Moreover, this microalloying approach not only control elastic properties, but also mitigates the failure mode of metallic glass. It demonstrates that restricting the motion of atoms in regions external to the shear band plays a critical role in inhibiting the propagation of the shear band.