Instrumented indentation study of plastic deformation in bulk metallic glasses

Mechanical properties and micro-plastic deformation behavior of five bulk metallic glasses (BMGs) were studied by instrumented indentation. These materials included La₆₀Al₁₀Ni₁₀Cu₂₀, Mg₆₅Cu₂₅Gd₁₀, Zr_52.5Al₁₀Ni₁₀Cu₁₅ Be_12.5, Cu₆₀Zr₂₀Hf₁₀ Ti₁₀, and Ni₆₀Nb₃₇Sn₃ alloys. Remarkable difference in deformation behavior was found in the load-displacement curves of nanoindentation and pileup morphologies around the indents. Serrated plastic deformation depended on the loading rate was found in Mg-, Zr-, and Cu-based BMGs. The subsurface plastic deformation zone of typical alloys was investigated through bonded interface technique using depth-sensing microindentation. Large and widely spaced shear bands were observed in Mg-based BMG. The effect of loading rate on the indentation deformation behaviors in different BMGs was elucidated by the change of shear band pattern.