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Short-range order (SRO) has a crucial impact on the mechanical strength of metallic alloys. Recent atomistic investigations defined an average SRO and attempted to correlate it with the yield strength. We propose that the local change in SRO upon slip advance must dictate the strengthening, and we elaborate the methodology to establish the “SRO change” on a slip plane considering the Wigner-Seitz cell. The model captures the variation of lattice resistance (Critical Resolved Shear Stress; CRSS) in the crystal as the SRO changes depending on the probability of neighboring atoms. The methodology was applied to Ni-V binary alloys for a wide range of compositions and stacking fault widths. The complex variation of CRSS with compositional variations shows good agreement with limited experimental results. 

This study establishes the Orientation Relationship (OR) between the austenitic and martensitic phases of the new Shape Memory Alloy (SMA) FeMnNiAl from both experiments and analytical modeling. Through Transmission Electron Microscopy (TEM) and Electron Back-Scatter Difraction, three distinct ORs, namely the Nishiyama-Wassermann (N-W), Pitsch, and Kurdjumov–Sachs (K-S) ORs are established. The observations of non-unique ORs are explained using the energy-minimization theory of martensite revealing dependence of OR on the internal morphology of the martensitic phase, whether twinned or stackingfaulted. It is shown that the twin-variants of an internally twinned martensitic structure individually explain the Pitsch and K-S ORs. The N-W OR was observed in a stackingfaulted substructure of martensite. Through a novel extension to the energy-minimization theory for stacking-faulted substructures, the N-W OR is explained. Thus, the current study challenges the notion of OR as a material-characteristic and reveals a dependence of the OR on the internal substructure of the martensitic phase in SMAs, further establishing the OR for the new SMA FeMnNiAl. 

This study establishes the Orientation Relationship (OR) between the austenitic and martensitic phases of the new Shape Memory Alloy (SMA) FeMnNiAl from both experiments and analytical modeling. Through Transmission Electron Microscopy (TEM) and Electron Back-Scatter Difraction, three distinct ORs, namely the Nishiyama-Wassermann (N-W), Pitsch, and Kurdjumov–Sachs (K-S) ORs are established. The observations of non-unique ORs are explained using the energy-minimization theory of martensite revealing dependence of OR on the internal morphology of the martensitic phase, whether twinned or stackingfaulted. It is shown that the twin-variants of an internally twinned martensitic structure individually explain the Pitsch and K-S ORs. The N-W OR was observed in a stackingfaulted substructure of martensite. Through a novel extension to the energy-minimization theory for stacking-faulted substructures, the N-W OR is explained. Thus, the current study challenges the notion of OR as a material-characteristic and reveals a dependence of the OR on the internal substructure of the martensitic phase in SMAs, further establishing the OR for the new SMA FeMnNiAl.