Extended Data Fig. 5: Composition of the η-phase precipitates.

a, A Ti atom map of a 5-nm-thick slice through the reconstructed volume from the martensitic phase in the hard region. The top part shows the atom map only; in the bottom part, precipitates are also highlighted by a set of isocomposition surfaces encompassing regions containing more than 10 at% Ti (dark green). b, A proximity histogram, that is, composition profile as a function of the distance to this isocomposition surface³⁰, calculated for all imaged precipitates in the dataset. The average Ti content fits the expected 25 at% almost perfectly. Fe replaces some of the Ni from the prototype Ni₃Ti phase, rendering it a (Ni,Fe)₃Ti phase with approximately 6–7 at% Fe and 66–67 at% Ni.