On the bcc/B2 interface structure in a refractory high entropy alloy

• Published in: Scripta materialia Vol. 223; p. 115071
• Main Authors: Kloenne, Zachary T., Couzinié, Jean-Philippe, Heczko, Milan, Gröger, Roman, Viswanathan, Gopal B., Clark, William A.T., Fraser, Hamish L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2023
• Subjects: Interface structure; Misfit dislocation; Nye tensor; Phase transformation; Refractory high-entropy alloy; Interface structure; Phase transformation; Misfit dislocation; Nye tensor; Refractory high-entropy alloy
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/j.scriptamat.2022.115071

A refined microstructure consisting of bcc precipitates embedded in an ordered B2 matrix has been observed in the refractory high entropy alloy (RHEA) AlMo0.5NbTa0.5TiZr, resembling an “inverted superalloy-like” microstructure. A planar {100} bcc/B2 interface exists in this state. Coarsening of the microstructure occurs after aging at 1000 °C for 6 h, resulting in a faceted interface. In this case, the primary plane of the interface is parallel to a {100} plane, while the step associated with the facet is parallel to a {110} plane. Misfit dislocations at the interface were observed on the {110} interface plane, with Burgers vector of a/2〈111〉bcc, which extend into the bcc phase, and have an average spacing of 13.7 ± 0.6 nm. No lattice invariant deformation (LID) normal to the primary {110} planes was observed, such that the transformation between the B2 and bcc phases constitutes a pure expansion. [Display omitted]