Miscibility gap narrowing on the phase diagram of Au Ni nanoparticles

Abstract In this paper, we study the mutual solid-state solubility in Au Ni nanoparticles with a mean size of ≈6 nm. Solid solution formation was probed via electron microdiffraction, EDX, and high-resolution STEM during sample heating in an electron microscope. As a result, a miscibility gap curve was constructed on the Au Ni phase diagram for ≈6 nm particles. It was shown that a quasi-homogeneous solid solution is already formed at 300–325 °C. The coarsening of particles induces decomposition of the solid solution and segregation of gold to the surface of nickel nanoparticles above 325 °C.