Phase diagrams of the binary systems of Nicotinamide (NA) with o-Nitroaniline (oNA), Cinnamic acid (CA) and 2- Methylimidazole (MIm) have been studied by thaw melt method. The result infers that all these mixtures are simple eutectic in nature. Eutectics (E) of NA-oNA, NA-CA and NA-MIm are formed at 65°C, 100°C and 102°C melting temperature, respectively and 0.780, 0.502 and 0.549 mole fraction of oNA, CA and MIm respectively. Heat of fusion (ΔH) of all the alloys and eutectics are also calculated with the help of mixture law. Thermodynamic stability in form of excess stability and ideal stability of the alloys of all systems are discussed in the present work. It gives an idea about the stability of eutectics and non-eutectics alloys of the systems. Interface morphology of the alloys predicts the faceted growth (α > 2) in all the cases in the light of Jackson’s surface roughness (a) theory. The microstructures of pure components of taken binary systems having high entropy of fusion and its eutectics have also been discussed.