A connection between the structural α-relaxation and the β-relaxation found in bulk metallic glass-formers

New metallic glasses containing La or Ce have been introduced having dynamic properties bordering on two extremes of conventional metallic glasses. This provides opportunity to test if the trends or correlations established before in molecular and polymeric glass-formers also exist in the broader family of metallic glasses. Due to the drastically different chemical and physical structures of metallic glass-formers than soft matter, there is no guarantee that any correlation found in the latter will hold in the former. If the trends and correlations are found, the result brings metallic glasses closer to the much wider classes of glass-formers in the similarity of properties. In non-metallic glass-formers, a general and fundamental connection has been established between the non-exponentiality parameter of the structural α-relaxation and the separation between its relaxation time τα and the β-relaxation time τβ. In this paper, we explore the experimental data of metallic glass-formers and show the correlation applies. An explanation of this correlation is given by the Coupling Model. The establishment of the correlation may facilitate the understanding of the roles played by the β-relaxation in macroscopic properties of metallic glasses including the relations to shear transformation zone, ductile-brittle transition in deformation, crystallization, and diffusion.