The microstructure and nanorelief of the amorphous Ti-Ni-Cu alloy subjected to high-pressure torsion
Bulk metallic glasses (BMG) are subject of great scientific as well as potential practical interest due to their unique mechanical properties including high strength, large elastic elongation along with low Young's modulus. High-pressure torsion (HPT) seems to be a promising method for the transformation of the structure of amorphous alloys and formation of multiple SBs in the structure. Shear bands formation can be observed in the direction along the applied force. The features of the microstructure of an amorphous Ti50Ni25Cu25 alloy subjected to HPT were studied by scanning force microscopy (SFM). The SFM data show that the foil of the sample after the HPT demonstrates a much more developed surface relief (up to 10 times deeper relief pits) than the similarly prepared Ti foil of the initial Ti50Ni25Cu25. In this case, the width of the hollows of samples' foil surface after the HPT is about 25 nm (which is close to the size of the observed clusters). Presumably, there is a difference in the free volume between clusters and their boundaries, and due to the lower density, the “body” of clusters is ionically polished more intensively, which is fixed by the more developed relief of the foil of the HPT-subjected sample and on TEM images.