Fig. 6: Atomic strain maps nearby the border of the precipitates.

a, b The filtered atomic resolution high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images of the martensite matrix nearby the interfaces. Yellow dash lines mark the region for the atomic strain analysis. Note that, in each case, the reference region is within the same martensite lath and ~150 nm afar from the interface (Supplementary Fig. 6). c, d Atomic strain maps of the region within 3 nm distance from the interfaces. e, f Density function theory (DFT) calculations on the solution energy of H atom at the tetrahedral interstitial sites and corresponding tetrahedral volume in α-Fe of precipitate #2 (green dash lines) and precipitate #3 (yellow dash lines). Note that the same magnitude of strains are applied to the [110] and \([1\bar{1}0]\) directions; and the positive and negative values of strain represent tensile and compressive strains, respectively. The [001]+1% notion in the legend means that an additional 1% tensile strain was applied along the [001] direction. Scale bars in panels a, b, 2 nm.