Microstructure and mechanical properties of in-situ nitride-reinforced refractory high-entropy alloy TiZrHfNbTa matrix composites

Abstract

Refractory high entropy alloy TiZrHfNbTa matrix composites reinforced with in-situ nitrides were prepared by vacuum arc melting. The designed composites are composed of BCC matrix and FCC nitride phases, with a particular orientation relationship between them: 111BCC∥011MN,101̅BCC∥200MN,11̅0BCC∥11̅1MN. The composites show enhanced strengths both at room temperature and high temperature compared with the matrix alloy and increase with the increment of N content. The ambient and elevated temperature (1000 ℃) compressive yield strength is up to 2125 MPa and 350 MPa, respectively, and decent fracture strains (>19.3%) at room temperature are maintained. The underlying strengthening mechanisms are discussed systematically, and the increase in strength is mainly attributed to the combination of dislocation strengthening, load-transfer effect and Orowan strengthening.