By Leibniz Institute for Solid State and Materials Research Dresden - IFW Dresden
The classical way to synthesize a glass consists of cooling a liquid so quickly that the crystallization is kinetically bypassed. Vitrification can be achieved even for multi-component metallic materials, the so-called bulk metallic glasses (BMGs), where cm-sized solids having liquid-like atomic arrangement can be synthesized thanks to the high viscosity of their melts. The absence of a periodic crystalline structure in these materials leads to a unique combination of properties, including near-theoretical strength, unusually large elastic limit and damage tolerance that can surpass that of conventional crystalline alloys. Two major limiting factors preclude the extensive use of these attractive materials in functional and structural applications: (1) the small size of the specimens, which is determined by the cooling rates achievable using conventional casting methods and (2) the limited plastic deformation at room temperature, which occurs via the formation and propagation of highly-localized shear bands with thickness in the nanometer range. Our work aims to solve these problems by focusing on three main aspects: - Synthesis and post-processing, where we optimize existing processing routes and develop new methods for the fabrication and microstructural improvement of BMGs. - Properties, where we evaluate and optimize the effect of processing on the characteristics of BMGs, in particular plasticity and shear band formation. - Analysis, where we investigate the deformation mechanism at different length scales, ranging from the µm-scale events characterizing the shear bands to the structural rearrangements occurring at the atomic scale.
