Surface Modification and Characterization of Bulk Amorphous Materials

Bulk metallic glasses (BMGs) are well known for their promising properties. Surface properties can be further improved by using certain techniques such as electron beam melting (EBM), laser beam melting (LBM), ion irradiation, ion implantation and neutron irradiation. BMGs especially Zr-based BMGs have numerous applications as structural materials. In this manuscript, the results are presented on microstructural investigations and phase formations in Zr-based BMGs modified by using above mentioned techniques. Microstructure was studied by scanning electron microscopy (SEM). Phase analysis was done by X-ray diffraction (XRD) and confirmed by energy dispersive spectroscopy (EDS). Vickers hardness was measured and correlated with the microstructure. The phases identified in Zr-Cu-Al-Ni alloy samples modified by EBM, LBM and ion irradiation are Ni-Zr, NiZr₂, CuZr₂, Cu₁₀Zr₇ and Al₂NiZr₆. ZrSi₂ phase was detected in Zr₅₅Cu₃₀Al₁₀Ni₅ and Zr₆₅Cu₁₇Ni₁₀Al₈ BMGs irradiated with Si⁺ (ions). About 20-35 % increase in hardness and elastic moduli was achieved by surface modification. Modifications of BMGs by electron and laser beams melted the materials surfaces while ion irradiation improved the mechanical properties of localized zones without melting.