Bulk Metallic Glasses and their composites: Additive Manufacturing and Modeling and Simulation

Bulk metallic glasses have emerged as competitive engineering material and have captured the attention of researchers across the globe because of their excellent mechanical properties (high hardness, high strength, and high elastic strain limit). However, they suffer from lack of ductility and fail catastrophically under tension. To this end, this problem can be over-come by forming a metal matrix composite such that some crystalline phases are introduced in the alloy during solidification, which provides a means of hindering rapid motion of shear bands. Thus, ductility and toughness increase while retaining high strength. The methods by which these crystalline phases are introduced and how they control the micro-structure have come under intensive investigation over the years. Various mechanisms (such as ex situ introduction , in situ precipitation, or devit-rification) are proposed on how to introduce crystalline phases and in-crease ductility and toughness. Recently, additive manufacturing has been proposed as the final solution of the problem as the final complex shape can be produced in a single step with composite structure in whole part ex- ploiting the inherent nature of the process. However, this technique is still in its infancy and numerous challenges exist on how to produce the final part without defects and how to control final microstructure. This study is aimed to address this problem from solidification processing and mod-eling and simulation perspective. A comprehensive coupled macroscopic and microscopic model is proposed to predict microstructure of solidify-ing alloy in liquid melt pool of additive manufacturing. Microstructure control is exercised by introducing inoculants during solidification. Their number density, size, and distribution are hypothesized to control micro-structure, and this is studied experimentally and validated by modeling and simulation. The methodology is claimed to be meritorious. The work is primarily intended for resear