Effects of Re microalloying on glass formation and mechanical properties of Zr–Cu–Al alloys

Abstract

The effect of microalloying with rhenium on a metallic glass-forming alloy (Cu₄₆Zr₄₆Al₈)_{100− x} Re _x (x = 1, 2) was investigated. Re possesses a positive enthalpy of mixing within the Cu–Re terminal system. Splat quenched foils of ≈40 µm in thickness display an amorphous structure. Their crystallisation temperature increases from T _x = 504 to 513°C with addition of Re at nearly constant glass formation temperature T _g = 445°C for the amorphous samples. In contrast, injection cast rods consist of B2-CuZr type phase dendrites, minor fractions of a cubic phase CuZrAl, and randomly distributed small particles of a Re-rich phase. This represents a novel concept in microalloying where Re-rich precipitates trigger the B2 phase formation. It leads to a unique combination of mechanical properties for as-cast rods, which display high strength at sizeable plastic deformation up to ε _p≈ 4% and an extended range of work-hardening prior to failure.

Keywords:

• amorphous alloys
• rhenium
• stress–strain measurements

Acknowledgments

The authors thank S. Müller-Litvanyi and S. Pichl for technical assistance and simulating discussions. S. Schmitz is grateful for the financial support provided by the “Pakt für Forschung Programm” for his work at the IFW Dresden.