Influence of mechanical-alloying parameters on the structure and properties of Cu₄₇Ti₃₄Zr₁₁Ni₈

The main objective of the research was to determine the mechanical-alloying conditions that ensure the fabrication of the Cu₄₇Ti₃₄Zr₁₁Ni₈ amorphous alloy. The experimental work involved the following mechanical-alloying parameters: milling time (0.5 h and 1 h) to interval time (0.5 h), ratio of grinding medium to material (5:1 and 10:1), the addition of an microwax powder and the process atmosphere (argon). Their effect on the structure, the amount of material obtained after milling, the size and shape of the powders, qualitative chemical composition and microhardness of the investigated Cu₄₇Ti₃₄Zr₁₁Ni₈ alloy were described. The mechanical alloying (MA) of the Cu₄₇Ti₃₄Zr₁₁Ni₈ alloy was carried out in a SPEX 8000 high-energy ball mill. The total mechanical-alloying time of each sample was 10 hours. Each 10-hour cycle consisted of milling time (1 h or 0.5 h) and interruption 0.5 h. Microwax powders were added to selected samples. Finally, eight samples for testing were obtained. The structure of the obtained powders was examined by X-ray diffraction (XRD). The chemical compositions of the prepared powders were investigated by scanning electron microscopy (SEM) with EDS. Electron transmission microscopy (TEM) was used to confirmation the fully amorphous structure of the sample. Microhardness was measured by using a Vickers hardness testing machine. Each of the applied milling parameters had an influence on the amorphization of the Cu₄₇Ti₃₄Zr₁₁Ni₈ alloy. The amorphous material was obtained in two cases after 1h of milling without adding microwax. After the TEM analysis it was found that the resulting powder is not completely amorphous. In the amorphous matrix, nanocrystallites were found: Cu51Ti14 and Cu5.38Ti3.33Zr3.29. The addition of microwax slowed down the amorphization. The highest microhardness was exhibited by the amorphous powders. Larger sample weights were obtained from the reactors to which microwax was added.