Room-temperature creep and structural relaxation of Mg–Cu–Y metallic glasses

Abstract Structural relaxation of Mg–Cu–Y metallic glasses occurs at room-temperature (∼0.7 T g ) and induces an abrupt embrittlement after periods of time that depend on the relative proportions of Cu and Mg. Internal friction measurements of as-quenched samples show that Mg 65 Cu 25 Y 10 is in a more relaxed state than Mg 85 Cu 5 Y 10 , suggesting a more compact structure for the alloy with a larger amount of Cu, which is the smallest atom in the system. Relaxation spectra, calculated from the anelastic component of nanoindentation creep curves, show that the two alloys are in a similar relaxed state, when they become brittle. The results are discussed in terms of the defects characterizing the disordered structure of the metallic glass.