Amorphous and partially crystallized metallic glasses: An indentation study

The plastic behaviour of amorphous, partially and totally crystallized Zr 41.25Ti 13.75Cu 12.5Ni 10Be 22.5 (at.%) Vitreloy1 samples is investigated using self similar instrumented indentation. Residual imprints are imaged using atomic force microscopy (AFM). Young's modulus and hardness are estimated using the value of the contact area derived from AFM imaging. Compressive tests and three point bending ultrasonic measurements are performed to probe the macroscopic properties. Despite a significant change in the shape of the imprint during the loading, we show that the amorphous alloy does not exhibit any size effect. Both for the amorphous and for the partially crystallized samples, the values of the Young modulus and the yield stress obtained by nanoindentation are consistent with those obtained by the macroscopic procedure. Inversely, the full crystallization samples display high brittleness on compressive tests while no cracking but only an increasing yield stress are observed using indentation. It is concluded that indentation is a well-suited test to probe the mechanical properties of the bulk metallic glasses.