Short range order and crystallization of Cu–Hf metallic glasses

Abstract

Detailed information on the atomic arrangement of glassy Cu54Hf46, Cu61Hf39 and Cu69Hf31 alloys has been obtained by the reverse Monte Carlo (RMC) simulation using high-energy X-ray diffraction and neutron diffraction data as input. Dominant cluster units are identified by means of the radical Voronoï tessellation technique. Cu-centred clusters show a stronger ordering level than the Hf-centred ones. Results are compared with those previously reported for analogous binary amorphous systems such as Zr–Cu and Zr–Ni. Additionally, the thermal stability of the studied Cu–Hf alloys has been inspected by in-situ high-temperature X-ray diffraction and differential scanning calorimetry measurements. A different structural evolution is observed for Cu69Hf31 compared with Cu54Hf46 and Cu61Hf39. Products of devitrification are identified and quantified. The better glass forming ability of Cu54Hf46 and Cu61Hf39 compared with Cu69Hf31 is explained in the view of short range order differences of glassy states and corresponding crystalline phases formed during devitrification.