Physico-Chemical nanomaterials science

Solidification and melting of Cu-Ni nanoscale droplet and effects of size and chemical depletion at the phase diagram 
Bilogorodskyy Yu.S.1,2, Shirinyan A.S.1
1 “Physical-Chemical Materials Science” Center of the NAS of Ukraine. Prospect Nauki, 46, Institute of Physics, Kyiv-03028, Ukraine. 
E-mail: urabelogorodsky@ukr.net
2 Research and Education Institution, “Cherkasy Regional Center of Works with Students”, Smelianska Street 132, Cherkasy 18029, Ukraine.

The solidification and melting of the liquid Cu-Ni droplet and equilibrium states in two-phase region are described due to modified Gibbs thermodynamics [1]. The Gibbs free energy of a changing nanoscale system is reassessed as the function of composition, temperature, pressure, the size of a new phase cluster inside the nanoscale system [2]. 
The phase change loops at the size-dependent temperature-composition phase diagram showing a two-phase equilibrium states at 25nm-80nm are calculated and constructed. It has been received the result that solidification and melting loops do not coincide with solubility curves - solidus and liquidus [3].
Decreasing the size yields at two-phase region of the phase diagram causes the decrease of the solidification/melting temperature and temperature width of phase transition, the increase of the solubility limit and the concentration width of the tranformation loop, the change of the shape and slope of the equilibrium curves. 

1.	Shirinyan A, Wautelet M, Belogorodsky Y. Solubility diagram of Cu–Ni nano-system // J Phys Condens Matter.-2006.-18. P. 2537–2551
2.	Shirinyan A, Wilde G, Bilogorodskyy Y. Solidification loops in the phase diagram of nanoscale alloy particles: from a specific example towards a general vision // J. Mater. Sci.-2018.-53. P. 2859–2879.
3.	Shirinyan A, Wilde G, Bilogorodskyy Y. Melting loops in the phase diagram of individual nanoscale alloy particles: completely miscible Cu–Ni alloys as a model system // J. Mater. Sci.-2020.-55. P. 12385–12402