Controversial discussion on the existence of the Hf and Zr monoborides and experimental proof by atom probe tomography

Abstract

The existence of the equiatomic HfB and ZrB phases with B1 (B27) structure types in binary and ternary alloy systems is heavily disputed in literature. In this work, we use atom probe tomography (APT) to further investigate assumed regions of these phases, as identified by scanning electron microscopy techniques in Mo–Hf–B and Mo–Zr–B alloys, which are potential structural materials for ultra-high temperature applications. In this paper, the chemical compositions of the phases are first analysed by means of APT, and the influence of impurities on the stability of the structures are discussed. Conclusively, our findings suggest that there is no evidence for monoboride phases with B1 structure type, consequently, we propose a new denomination for the existing phases.