  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.
