Tuning properties and behavior of magnetron sputtered Zr-Hf-Cu metallic glasses

Abstract Amorphous ternary Zr-Hf-Cu thin-film alloys with glass-like behavior were deposited by non-reactive conventional dc and high-power impulse magnetron co-sputtering using three unbalanced magnetrons equipped with Zr, Hf and Cu targets. The Zr and Hf targets were operated in a dc regime while the Cu target in a high power impulse regime. Two series of films with a gradually increasing Hf/(Hf+Zr) ratio at 46 at.% Cu and 59 at.% Cu were deposited. The effect of the elemental composition on the structure, thermal behavior, mechanical and surface properties, electrical resistivity and oxidation resistance was systematically investigated. We found a clear correlation among the evolution of the glass transition temperature, crystallization temperature, hardness and effective Young's modulus with increasing Hf/(Hf+Zr) ratio. A linear increase of these quantities is attributed to an increase of the average bond energy in the films as Hf gradually substitutes Zr. The Zr-Hf-Cu thin-film metallic glasses exhibit enhanced hardness (up to 7.8 GPa), enhanced thermal stability and oxidation resistance, very smooth (surface roughness down to 0.2 nm) and hydrophobic surface (water contact angle up to 109°), and very low electrical resistivity (lower than 1.9 × 10 −6 Ωm).