Deformation behaviour of a Zr-Cu-based bulk metallic glass

While inelastic mechanical behaviour of crystalline materials is well-understood in terms of lattice defects, bulk metallic glasses (BMGs) pose significant challenges in this respect due to their disordered structure. They can be produced by rapid cooling from the liquid state (among other technique) and, thus can be frozen as vitreous solids. Due to the absence of a long-range order in atomic structure and a lack of defects such as dislocations, BMGs generally show unique mechanical properties such as high strength and elastic limit, as well as good fracture toughness and corrosion resistance. Typically, inorganic glasses are brittle at room temperature, showing a smooth fracture surface as a results of mode-I brittle fracture. At small scale, it was well documented that inelastic deformation of bulk metallic glasses is localised in thin shear bands. So, in order to understand deformation mechanisms of BMGs comprehensively, it is necessary to investigate formation of shear bands and related deformation process. In this thesis, a history of development of BMGs is presented, followed by a review of fundamental mechanisms of their deformation. [Continues.

Indentation study of mechanical behaviour of Zr-Cu-based metallic glass

It has been well known that plastic deformation of bulk metallic glasses (BMGs) is localised in thin shear bands. So, initiation of shear bands and related deformation should be studied for comprehensive understanding of deformation mechanisms of BMGs. In this paper, indentation techniques are extensively used to characterise elastic deformation of Zr-Cu-based metallic glass, followed by a systematic analysis of initiation and evolution of shear bands in the indented materials. Our results, obtained with a suggested wedge-indentation technique, demonstrated initiation of shear bands in materials volume