Precipitation of ordered phases in metallic solid solutions: A synergistic clustering and ordering process

The precipitation mechanism of ordered phases in metallic solid solutions has been a long-standing controversy due to the competing roles of chemical clustering (or phase separation) and chemical ordering. In the present study, this controversy has been resolved through the coupled use of aberration-corrected high-resolution scanning transmission electron microscopy and atom probe tomography. The experimental results, obtained at atomic resolution, can only be interpreted satisfactorily on the basis of phase separation via spinodal decomposition followed by chemical ordering.