Microstructure Characterization and Fracture Toughness of Laves Phase-Based Cr–Nb–Ti Alloys

Abstract

Three Laves phase-based alloys with nominal compositions of Cr2Nb–xTi (x = 20, 30, 40, in at%) have been prepared through vacuum non-consumable arc melting. The results show that the microstructures of Cr2Nb-(20, 30) Ti alloys are composed of the primary Laves phase C15–Cr2(Nb,Ti) and bcc solid solution phase, while the microstructure of Cr2Nb–40Ti alloy is developed with the eutectic phases C15–Cr2(Nb,Ti)/bcc solid solution. The measured fracture toughness of ternary Laves phase C15–Cr2(Nb,Ti) is about 3.0 MPa m1/2, much larger than 1.4 MPa m1/2 for binary Laves phase Cr2Nb. Meanwhile, the fracture toughness of Cr2Nb–xTi (x = 20, 30, 40) alloys increases with increasing Ti content and reaches 10.6 MPa m1/2 in Cr2Nb–40Ti alloy. The eutectic microstructure and addition of Ti in Cr2Nb are found to be effective in toughening Laves phase-based alloys.