Fig. 2: The transformation path from the (110) FTB of μ phase to the partial structure of P (or σ) phase.

Note that the hexagonal description is also often used for the rhombohedral μ phase. Some typical plane/orientation relationships are: (110) corresponds to (1-12)^H, [1-11] corresponds to [42-1]^H, and [1-10] corresponds to [110]^H. Please refer to Supplementary Fig. 1 for details. a–d Schematic illustration of the transformation process via dislocation climb. a The original FTB of the μ phase. b Smaller metal (yellow) atoms diffuse into the FTB. c The resultant dislocation, resembling a Frank interstitial loop, climbs to the right, converting the local structure into that of the P phase, which is shown in (d). Note that the Burgers vector of the climbing dislocation has both a parallel and a vertical component. e–j illustrate the details using an atomic model. The purple and blue atoms represent (Co, Cr, Ni) and (W, Mo, Re), respectively. e Atomic model of the FTB, projected along [1-11]_μ. The orange dotted line marks the interface position of the FTB, into which the small atoms (represented by yellow balls) in (f) diffuse/insert. f An extra row of atoms gradually diffuse into the FTB; see Supplementary Fig. 8 for additional information and red dashed circles. All the atoms inside the orange dotted box experience translational displacement with Burgers vector b_∥ = 1/2[1-10] and vertical displacement with b_⊥ (its magnitude is 1.4 Å), resulting in (g), a partial structure of P phase. h–j The HAADF images corresponding to the atomic model projections in (e–g). Scale bars of (h–j) are 0.5 nm.