Comment on “A TEM study of martensite habit planes and orientation relationships in Cu–Al–Ni shape memory alloys using a fast Δg-based method”

A recent study of Cu–Al–Ni alloys has demonstrated the convenience of using parallel Δg’s for measuring the irrational habit planes of martensite, but the paper lacks a theoretical basis. A key point that is missing is the link between the parallel Δg’s and the lattice-invariant shear direction in the phenomenological theory of martensitic crystallography (PTMC). After clarifying the equivalency between the PTMC and the parallel Δg model, this work presents calculated results based on the PTMC and the Δg model, showing consistency with the experimental results.