Fig. 5: Comparison of SRO in AH and AN500 samples.

a, Accumulated 1NN to 200NN SRO calculations of the entire APT dataset of AH (a) and AN500 (b). In the AH sample, all the pairs exhibited SRO values in the range of −0.00112 ≤ α ≤ 0.00141 at 200NN, indicative of little or no SRO, effectively showing a near-random distribution. In the AN500 sample, the preferencing between the atomic species was more pronounced, with the pairwise SRO values ranging within −0.00602 ≤ α ≤ 0.00557. The Ni–Ni and Cr–Cr pairs tended to cluster, whereas the Ni–Cr pairs exhibited anti-clustering. After annealing, the degree of clustering of Cr increased, with Cr–Cr values changing from 0.00080 in the AH condition to 0.00409 in the AN500 condition. The tendency for anti-clustering of the Cr–Ni increased after annealing, from −0.00063 in the AH state to −0.00453 in the AN500 condition. The random regions (±0.00022) were shown in grey in both figures. The NN–distance relationships in an ideal CoCrNi model are 0.25 nm for 1NN–12NN, 0.36 nm for 12NN–18NN and 0.44 nm for 18NN–42NN. c,d, Comparison of SRO before (c) and after (d) reconstitution for different atom pairs. These results were obtained by averaging two of our experimental APT datasets for each condition, with a focus on the seventh nearest neighbour (kNN = 7). The data were extrapolated to account for no noise and 100% detector efficiency, using the corrections and simulations developed in this study. These corrections and simulations assume a lateral resolution of 0.25–0.50 nm and an in-depth resolution of 0.10–0.20 nm. The standard deviation of error associated with these estimates is detailed in Supplementary Table 4.

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