Research Projects

Metallic glasses are slowly coming of age and finding applications in many areas of space, defense and other industries. It is an area, which will grow more with the advent of additive manufacturing as metallic glasses beyond the critical casting thicknesses can be synthesized by 3-D printing. Despite all these advantages, one of the problems which remains to be addressed in glass research is its limited or no ductility, especially in tension. In this regard, the present work focusses on improving the tensile plasticity in bulk metallic glasses. The addition of immiscible elements like Sn, Pb and Fe in Cu-Zr based amorphous alloy would promote the dispersion of soft crystalline phases in an amorphous matrix. Sn and Pb have positive enthalpy of mixing with Cu, which makes it likely for them to precipitate as crystalline phases in the amorphous matrix. One of the primary reasons for the catastrophic failure of metallic glasses in tension is the rapid propagation of shear bands during plastic deformation. The addition of soft secondary phases like Sn and Pb can stop the propagation of shear band propagation effectively. Addition of Fe is done to understand the effect of shear modulus of the secondary phases on the plastic behavior of bulk metallic glass composites. As a first step, we will do the initial synthesis of composites by using melt-spinning in the form of thin ribbons. Once, the right compositions are identified, we will attempt to produce the same compositions in bulk form using suction casting. Both the ribbons and bulk samples will be structurally characterized using standard techniques like X-ray diffraction, Scanning electron microscopy, Differential Scanning calorimetry and Transmission electron microscopy. The thermal stability of the samples will be tested by heat treating them in a protective atmosphere. Mechanical testing will be performed by using indentation on both the ribbons and the bulk samples. Nanoindentation will be performed on the individual phases to understand the mechanical behavior of individual phases. Further testing will be carried out on the bulk samples using standard compression and tensile samples. Detailed analysis will be performed to correlate the obtained microstructure with the observed mechanical properties of the composites.