A review on nano-/ultrafine advanced eutectic alloys

Eutectic alloys with two alternating phases in the microstructure are well known for their excellent mechanical properties as well as superior castability. In this review, we have surveyed a large number of eutectic/near-eutectic alloys, their recent advancement mostly in Al-, Ni-, Ti-, Fe-base binary, ternary, multicomponent, and high entropy alloy systems. The fundamental of the growth mechanisms, interface instability, and different types of eutectic reactions are discussed. The effect of alloy addition on the evolution of nano-/ultrafine eutectic microstructure upon solidification, the morphology of phases, and their length scale in the range of 80 nm–2 μm, have been thoroughly illustrated with examples and case studies. The adopted methods to find eutectic composition in multicomponent systems have been guided. The enhanced hardness, and superior yield strength under tension and compression up to 2.5 GPa at room temperature as well as at high temperature up to 1000 °C has been correlated with the microstructure. The mechanism of slip transfer through the lamellae interface and the role of elastic constants of the individual phases on the evolved plasticity have been interlinked. Furthermore, an insight to the functional and critical mechanical properties, especially the evolution of soft magnetic properties, large fatigue limit, high temperature creep behavior, wear and corrosion resistance of a large number of eutectic alloys are discussed along with the engineering applications.