Secondary Relaxation in Metallic Glass Formers: Its Correlation with the Genuine Johari-Goldstein Relaxation

We report. experimental evidence for the existence of Johari-Goldstein (JG) relaxation in metallic glass formers. By using the hyperquenching-annealing-calorimetric approach, we study the dynamics of the secondary (beta) relaxation in La55Al2.5Ni20 metallic glasses, The observed beta relaxation exhibits a typical feature of the (T-g) obeys the relation E-beta = 26.8RT(g). The correlative degree between the beta and the primary alpha relaxations is closely associated with the liquid fragility. By a survey of the sub-T-g relaxation data of other metallic glass systems, we have determined the E-beta values that find the correlation E-beta = 26 1RT(g), indicating that JG relaxations are intrinsic in metallic glass formers. By analyzing the primitive relaxation time of the JG motion. T-0.JG, and the crossover time in the Coupling model, t(e), we discuss why the excess wing rather than the JG peak (or shoulder) is present in metallic glass systems.