Correlation between glass-forming ability, thermal stability, and crystallization kinetics of Cu-Zr-Ag metallic glasses

Abstract

The glass-forming ability (GFA) of the Cu-Zr-Ag system is evaluated based on the large amount of literature data available and discussed in the frame of a predictive amorphization criterion which combines topological instability and electronic criteria. The correlation between GFA, thermal stability, and crystallization kinetics of (Cu0.5Zr0.5)100−xAgx (x = 0, 2, 6, and 10) metallic glasses is further investigated. The enhancement of the GFA of the alloys and the thermal stability/fragility of the supercooled liquid can be traced back to a large size effect/volume mismatch and electronic effects. However, the apparent activation energy of crystallization decreases with increasing Ag content in the alloys which may be due to a nanoscale microstructural heterogeneity induced by the Ag addition. At a certain Ag content, a small amount of AgZr crystals precipitate together with Cu10Zr7 and CuZr2 and the crystallization mechanism changes from interface-controlled one-dimensional growth to three-dimensional growth with different nucleation rates.