Energy functions, structure, mechanism of solidification, modulus of rupture and tensile tests of the binary organic eutectic system benzoic acid-diphenylamine

Abstract

To elucidate the mechanism of eutectic crystallization, the spontaneous solidification and directional velocity of crystallization from binary molten mixtures of benzoic acid and diphenylamine have been studied. The structure of the liquid eutectic has been explored by viscosity measurements of eutectic and non-eutectic melts at low and high temperatures. The activation energy E vis for eutectics and non-eutectics is found to be a function of temperature. Microscopic studies of various modes of crystallization of the eutectic and non-eutectics were made to investigate the characteristics of the solid eutectic. The relationship between the rate of solidification and mechanical strength of the eutectic and its constituent materials has been investigated. Evidence has been obtained for a parabolic variation in the strength of the composite material with growth velocity V of the form V=K(ΔT) 2 , giving a relation for the dislocation growth mechanism. Directionally solidified eutectic grown at a velocity of 5.5 × 10 −9 m 3 s −1 yields three- to fourfold increases in the modulus of rupture and tensile strength in comparison with its random growth in ice-cold water (273 K), whereas no significant improvement in these properties was observed at low or high growth velocity.