Thermal Stability and Mechanical Properties of Cu-Based Bulk Glassy Alloys in Cu<SUB>50</SUB>(Zr<SUB>1-x</SUB>Hf<SUB>x</SUB>)<SUB>45</SUB>Al<SUB>5</SUB> System

Abstract

The thermal stability, crystallization and mechanical properties of the Cu 50 (Zr 1-x Hf x ) 45 Al 5 (x = 0 to 1) bulk glassy alloys have been investigated. The glass transition temperature (Tg), crystallization temperature (T x ), liquidus temperature (T 1 ) and the supercooled liquid region ΔT x (= T x - T g ) increase with increasing Hf content. The reduced glass transition temperature (T g /T l ) is in the range from 0.603 to 0.615. The Vicker's hardness (Hv), Young's modulus (E) and compressive fracture strength (σ c,f ) of the bulk glassy alloys increase linearly with increasing Hf content and reach the maximum values of 627, 121 GPa and 2262 MPa, respectively, for Cu 50 Hf 45 Al 5 . A different crystallization behavior is observed for Cu 50 Zr 45 Al 5 and Cu 50 Hf 45 Al 5 glassy alloys. The final crystallization phases are Cu 10 Zr 7 for the former alloy, and Cu 10 Hf 7 and CuHf 2 for the latter alloy.