Visco-elasticity and mechanical relaxation behavior in La-based metallic glasses

Dynamic mechanical relaxation process is one of the important issues to understand mechanical/physical properties of metallic glasses. In the current research, dynamic mechanical relaxation behavior of La62Al14(Cu-5/ Ag-6(1/6))(20)(Ni1/2Co1/2)(4) and (La0.7Ce0.3)(65)Al10Co25 bulk metallic glasses were investigated by mechanical spectroscopy. Unlike the typical Zr- or Cu-based metallic glasses, (La0.7Ce0.3)(65)Al10Co25 metallic glass shows an evident beta relaxation process. On the other hand, La62Al14(Cu5/6Ag1/6)(20)(Ni1/2Co1/2)(4) metallic glass presents a shoulder relaxation process. Physical aging below the glass transition temperature Tg induces a decrease of the concentration of defects, which corresponds to a reduction of the intensity of the beta relaxation. During aging process, the amplitude of beta relaxation (oE) decreases, while the relaxation time (tau beta) increases. In organic glasses, it was reported that the changes of In(tau beta) and In(oEmax) are linearly correlated with In(tau beta)=b-a In (oEmax), this correlation has also been found in metallic glass. This behavior is discussed in the framework of the asymmetric double well potential (ADWP) model, and U and o are used to characterize ADWP. It is suggested that during the aging process, the U/o ratio remains basically unchanged, which is close to the coefficient describing the linear correlation between In(tau beta) and In(oEmax) (U/oa).

Automated summary

The dynamic mechanical relaxation behavior of two different bulk metallic glasses was examined, showing distinct characteristics in the relaxation process, where physical aging resulted in a decrease in beta relaxation intensity and an increase in relaxation time. This behavior was found to be linearly correlated, similar to that observed in organic glasses, suggesting a potential common mechanism underlying relaxation processes in different types of glasses.