Effect of Fe addition on the glass-forming ability, stability, and mechanical properties of Zr50Cu34-xFexAl8Ag8 metallic glasses

Abstract

Zr50Cu34-xFexAl8Ag8 (x = 0, 2, 4, 6, and 8) alloy bars of different diameters were prepared by copper mold suction casting and copper mold casting. The compressive mechanical properties of metallic glass samples with different Fe contents were determined by a universal testing machine. The microstructure and thermodynamics of the alloy samples were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. According to the experimental results, Fe doping had a significant effect on the glass-forming ability, stability, and mechanical properties of these metallic glasses. The maximum diameter of the Zr50Cu32Fe2Al8Ag8 metallic glass bar was 15 mm, and the cooling rate of the alloy sample was 7.7 K/s. The addition of Fe inhibited the formation of stable crystalline phases inside the alloy sample and improved the glass-forming ability of the metallic glass. With the addition of Fe, the DSC curve of the alloy sample moved to higher temperatures, and the characteristic temperatures and the stability of the metallic glass increased. The fracture strength (σmax) and ultimate strain (εf) of the metallic glass samples reached their maximum values of 1917.6 MPa and 3.97 %, respectively, for Zr50Cu30Fe4Al8Ag8. Compared with the Fe-free Zr50Cu34Al8Ag8 metallic glass, σmax and εf increased by 51.4 MPa and 1.19 %, respectively. With the addition of Fe, the change in the distribution and content of free volume inside the metallic glass sample is the main reason for the improvement of its mechanical properties. This study shows that trace element doping has an important effect on the properties of metallic glasses.