Fig. 5: The HAADF image and schematic illustration of the thickening process of intergrowth P phase.
a The HAADF image projection along [1-10]μ showing the thickening process of intergrowth P phase. The orange arrow in (a) marks the direction of the progressive transformation. Regions A–C corresponds to the three sequential stages of transformation. b, c Atomic models corresponding to the regions A and C in (a), respectively. The differences between the atomic arrangement in region A and that in region C are indicated by the blue block layer (thickness of 4D) in (b). The black dashed lines mark the interface position of the FTBs in (b, c) and the distances between two adjacent FTBs are added. The atomic structures of region C and A can also be simplified as line 1 and line 2, respectively. Their endpoints and turning points indicate the presence of the FTBs here, numbered by the green text in (d). d Schematic illustration of the location of FTBs changed by the transformation in (a). The FTB at number 5 transforms to perfect μ and an identical FTB appears at number 5’. e The schematic example of the number of FTBs changed by the same transformation. The structure of line 3 is similar to that of line 1, only different at the top. f The brief schematic of the growth process of intergrowth P (or σ) phase in μ phase. The schematic (i) in (f) shows that there are many randomly distributed original (110) FTBs in the parent μ phase, represented by the solid black lines, with a total number of m. Via the local atomic short-range diffusion at FTBs, n FTBs can proliferate to be 3n as illustrated by the first and second FTB shown in (ii), and their distribution and spacing can also be regulated as illustrated by the ith and nearby FTBs shown in (iii). The new phase in schematic (iii) is an example of the P phase (FTBs with a spacing of 2D). If the new phase is σ phase, the spacing between FTBs is D.
