Decoupling of pronounced beta and alpha relaxations and related mechanical property change

A pronounced secondary beta-relaxation is observed in a newly-developed La-based bulk metallic glass that has critical size at least 10 mm in diameter. It is demonstrated that the beta-relaxation becomes pronounced with increasing annealing time due to decoupling from the a relaxation. By using nanoindentation, we find that the shear-transformation-zone (STZ) volume and involved atoms increase in the annealed samples, implying that the decoupling of the beta-relaxation from the a relaxation can promote the movement of local atoms. However, the correlation of beta-relaxation with ambient compressive plasticity of bulk samples is not revealed. (C) 2013 Elsevier B.V. All rights reserved.