An interesting phase transformation was imaged in a refractory high entropy alloy using Atom Probe Tomography. The APT ion maps above shows partitioning of Al during microstructural evolution, with increase in annealing time. The initial microstructure (left) consists of channels of B2 crystal structure (rich in Al) and discrete body-centered cubic (BCC) precipitates (lean in Al) in a checkered pattern. With annealing time, the B2 channels undergo necking and break-off to form discrete precipitates while BCC becomes the channels. This results in a dramatic change in mechanical properties of the alloy.
Recorded on CAMECA LEAP 5000 XS at University of North Texas, Denton. Image courtesy of S. Dasari.
V. Soni et al. Phase inversion in a two-phase, BCC+B2, refractory high entropy alloy. Acta Materialia Vol 185, p89-97 (2020).