Microstructure and size effect in ultrafine (Ti0.705Fe0.295)100−xSnx (0 ⩽ x ⩽ 4 at.%) composites

The effect of Sn addition on the microstructure evolution in ultrafine lamellar (Ti0.705Fe0.295)100−xSnx (0 ⩽ x ⩽ 4 at.%) eutectic composites and size effect during Vickers microhardness measurements at load in the range of 0.049 N and 19.61 N have been studied. The hardness of all the lamellar composites with varying Sn content decreases with increase of applied load pointing the existence of normal indentation size effect (ISE). The load dependence microhardness values have been analysed using existing models such as, Meyer's law, depth dependence hardness model, proportional specimen resistance model (PSR), modified PSR model, Hays-Kendall approach, and elastic-plastic deformation model. Furthermore, the load dependent microhardness has been correlated with the dislocation density, microstructure length-scale, and ISE. The microscopic mechanisms of ISE and strain hardening behaviour in lamellar eutectic composite have been explored.