Unusual effect of high pressures on phase transformations in Ni$_{62}$Nb$_{38}$ alloy

Binary Ni$_{62}$Nb$_{38}$ alloy belongs to the unique class of binary off-eutectic systems, which are able to form a bulk glassy state [L. Xia et al., J. Appl. Phys. 99 (2006) 026103]. In the present work, the ($p$, $T$) phase diagram of Ni$_{62}$Nb$_{38}$ alloy was first determined for a wide thermodynamic range with temperatures from $300$\,K to $6000$\,K and with pressures from $1$\,atm to $1.2\times10^7$\,atm. For this thermodynamic range, elements of the phase diagram such as the liquid-crystal coexistence line and the glass transition line are defined. Our results reveal good agreement between the simulation results and the known experimental values of the liquidus temperature and the glass transition temperature for the isobar $p=1$\,atm. The phase diagram is detailed for pressures greater than $1\times10^{7}$\,atm. For the first time, the phase separation conditions at which the liquid Nb and crystalline Ni phases coexist in the system were determined.