A general model for the crystal structure of orthorhombic martensite in Ti alloys

The present work develops a novel unified approach to describe the crystal structure of orthorhombic martensite (α′′) in Ti alloys independent chemical composition. By employing straightforward yet highly instructive solid sphere model for basic tetrahedral structural unit structures involved β ↔ α′′/α′ martensitic transformation are categorized into several intermediate configurations. Importantly, new metric is introduced, δ, which unambiguously characterizes atomic positions inside cell depending on unit-cell geometry. Furthermore, exclusive use relative quantities geometry and atom renders developed herein alloy content. In this way, shortcomings commonly suggested metrics α′′ eliminated. Subsequently, methodology applied analyse compare across broad range based experimentally measured parameters. From analysis it emerges that large fraction configurations along b.c.c.– Cmcm –h.c.p. path not observed quenched alloys. threshold between not-observed remaining well identified with an ideal structure, found compressed its c axis.