The intermetallic compound NiAl received much attention because of its outstanding physical and chemical properties, compared to Ni-based superalloys. However, its use is restricted by the limited mechanical properties. An improved performance can be achieved by manufacturing an in-situ composite with NiAl matrix strengthening with embedded refractory metals, such as Cr, Mo, by directional solidification of alloys with eutectic composition. Based on own experimental results, additional data from the literature and necessary refinement of the sub-systems, a thermodynamic database of the Al-Cr-Mo-Ni system was developed in the present work in order to support the selection of alloys for directional solidification, microstructure modeling and thermodynamic modeling of higher order systems.
In this study, the liquidus and solidus temperatures of the NiAl-Mo section were measured with a laser heating experiment. A better model for the ordering transition among the A2/B2 phases was employed and a new optimization for the Al-Mo-Ni system was performed. The description of the Al-Mo-Ni system was significantly improved. A few adjustments for the Al-Cr-Ni and Cr-Mo-Ni databases from literature were made. The primary solidification surface of the system NiAl-Cr-Mo was investigated experimentally. Using own experimental results and additional data from the literature, a quaternary database of the system Al-Cr-Mo-Ni was established. The description of the liquid phase was extended over the whole composition range of the quaternary system. The calculation results agreed well with the experimental data.