**Dynamic Mechanical Relaxation in LaCe-Based Metallic Glasses: Influence of the Chemical Composition**

### **Minna Liu 1, Jichao Qiao 1,\*, Qi Hao 1, Yinghong Chen 1, Yao Yao 1, Daniel Crespo 2 and Jean-Marc Pelletier 3**


Received: 13 August 2019; Accepted: 14 September 2019; Published: 17 September 2019

**Abstract:** The mechanical relaxation behavior of the (La0.5Ce0.5)65Al10(CoxCu1−x)25 at% (x = 0, 0.2, 0.4, 0.6, and 0.8) metallic glasses was probed by dynamic mechanical analysis. The intensity of the secondary β relaxation increases along with the Co/Cu ratio, as has been reported in metallic glasses where the enthalpy of mixing for all pairs of atoms is negative. Furthermore, the intensity of the secondary β relaxation decreases after physical aging below the glass transition temperature, which is probably due to the reduction of the atomic mobility induced by physical aging.

**Keywords:** metallic glasses; mechanical spectroscopy; mixing enthalpy; Kohlrausch–Williams–Watts equation; structural heterogeneity
