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When water is cooled at or above the critical rate for vitrification, it forms an amorphous glass whose structure more closely resembles that of the solid than the liquid form. This change in water's structure upon vitrification has implications for its behavior as a solvent. We examined the supercooling of aqueous salt solutions under ambient pressure by molecular dynamics using a monatomic model of water, mW, with a coarse-grained model of salt, S, their pair potential being described by the Stillinger-Weber potential, and found that aqueous solutions of water under 15% solute, when cooled at the critical rate for vitrification, form two phases: ion-rich, solvated regions and low density amorphous ice, consistent with prior results of simulations and experiment.1 Due to limitations of mW when attempting to model the behavior of water at high pressure, our investigations of this phenomenon by molecular dynamics had been conducted only under ambient pressure conditions. We reproduced the results of this previous work by cooling simulations of a 10% S in mW system, and validated these by analysis of density, fraction of 4-coordinated water, radial distribution function, and extent of phase segregation. Utilizing a more recently developed monatomic water model, ML-BOP, which is better able to represent the behavior of water above ambient pressure, including where the liquid-liquid transition line displayed by the phase diagram of supercooled water is located, we parameterized a hybrid force field, which describes the pair potential of water molecules among themselves by a Tersoff potential, while that between water molecules and ions remains described by an mW-S Stillinger-Weber potential. Due to differences in the energetics and dynamics between ML-BOP and mW, we found that weakening of water-solute interactions and depression of the cooling rate is required to obtain the same state of phase segregation for the hybrid system. Upon realization of the force field, we might investigate the solvation behavior of water upon supercooling at high pressures.