Unveiling the Intricacies of a Ductile‐Phase Toughened Intermetallic: An In‐Depth Exploration of a Eutectic Mo–Si–Ti Alloy and its Mechanical Behavior

Abstract

In this work, we present the development of directional solidification for a novel high‐temperature Mo‐20Si‐52.8Ti (at. %) ternary alloy using a modified Bridgeman type apparatus. The resulting alloy exhibits a microstructure consisting of a body‐centered cubic solid solution BCCss and a hexagonal silicide (Ti,Mo)5Si3 with approximate volume fractions of 50% for each phase. The phases exhibit a crystallographic orientation relationship with and . Different solidification velocities were imposed which revealed an inverse relationship to the lamellar spacing according to a Jackson‐Hunt type scaling. Mechanical characterization using Vickers indentation demonstrated that the BCCss accommodates plasticity through dislocation mediation, while the silicide phase exhibits high hardness and brittleness, serving as a crack initiation site. Crack propagation was arrested and deflected at the interface to the BCCss. Fracture toughness measurements via indentation yield a fracture toughness of 3.7 MPa√m for the silicide, somewhat higher than previously reported values for Si‐ and Cr‐based intermetallics. The directionally solidified (DS) specimens showed an enhanced fracture toughness attributed to a greater BCCss length scale; thus, combining the ductile and hard phases resulted in a ductile‐phase toughened intermetallic composite. The findings open up new possibilities for the design of advanced intermetallic composites with improved toughness performance.This article is protected by copyright. All rights reserved.