Deformation mechanism of reinforcements in Nb ₄ FeSi‐containing Nb–Si‐based in situ composites: eutectoid transformation and reorientation behavior

Abstract Nb–Si‐based in situ composites are receiving attention as a substitute for Ni‐based alloys in aerospace, while poor toughness limits its application. In this work, the toughness of Nb 4 FeSi‐containing Nb–Si‐based alloys was improved by hot deformation. The different deformation behaviors of reinforcements from traditional alloys, including the eutectoid decomposition of β‐Nb 5 Si 3 , and the stacking faults (SFs) and reorientation‐induced plasticity (RIP) effect of Nb 4 FeSi, are revealed. During hot deformation, the β‐Nb 5 Si 3 phase undergoes the eutectoid decomposition to obtain the α‐Nb 5 Si 3 and niobium‐based solid solutions (Nbss) phases, which α‐Nb 5 Si 3 and Nbss satisfy the relationship {110} α //{110} Nbss . The [] SFs and lath‐like reoriented variants are formed in the Nb 4 FeSi phase, where the matrix and variants follow [001] m //[111] v , () m //() v . Furthermore, the interface between matrix and variant is Σ33c symmetrical tilt boundaries, manifested as ()/60°. The fracture toughness of the deformed alloy reaches 18.31 MPa·m 1/2 at 1300 °C/0.005 s −1 /0.7, which is 49% higher than the initial alloy.