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_52.5Al₁₀Ni₁₀Cu₁₅Be_12.5, Cu₆₀Zr₂₀Hf₁₀Ti₁₀, and Ni₆₀Nb₃₇Sn₃alloys. 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.