Mechanical properties of Zr-based bulk metallic glasses with different Al contents

(Zr64.8/90Cu14.85/90Ni10.35/90)90+xAl10-x bulk alloys with x=-4, -3, -2, 0, 2, 4 and 6 were prepared with copper mold casting method. The effects of Al contents on mechanical properties of Zr-based bulk metallic glasses were studied by X-ray diffraction(XRD), universal testing machine, microhardness tester and scanning electron microscope(SEM). The results showed that with the decrease of the content of Al, the structure of alloys changed from amorphous/crystal composite materials with mainly amorphous phase into completely amorphous materials, and then into amorphous/crystal materials with mainly crystalline phase, and finally into fully crystalline materials. It meant that Zr-based bulk metallic glasses with completely amorphous structure could be fabricated by adjusting Al content. The structure of the alloy was completely amorphous when x=-2, with alloy composition of Zr63.36Cu14.52Ni10.12Al12, and the compressive plastic strain (εp) of the alloy was up to 20.6%. The yield strength (σs), maximum strength (σm) and facture strength (σf) were 1740.6, 2030.7 and 1510.5 MPa, respectively, and the “work-hardening” characteristic could be seen from the stress-strain curve. It demonstrated that Zr-based bulk metallic glasses with excellent compressive plasticity and high compressive strength could be fabricated by adjusting Al content. With the decrease of the Al content, the microhardness of alloy samples firstly increased and then decreased. When x=2, the structure of the alloy was amorphous/crystal composite material, and the hardness reached HV719.8, which indicated that higher microhardness was obtained in the alloy. ©, 2015, Editorial Office of Chinese Journal of Rare Metals. All right reserved.