Thermophysical properties and rapid solidification of an undercooled liquid hexabasic Ni-based alloy

Abstract

The surface tension and specific heat of liquid Ni-5%Cu-5%Fe-5%Co-5%Sn-5%Ge hexabasic alloy were measured over a broad range of temperature. The maximum undercooling obtained in the experiments is 363 K (0.22 T L). The surface tension value is determined as 1.460 N m−1 at the liquidus temperature of 1652 K, while its temperature coefficient is –6.361 × 10− 4 N m−1 K−1. The specific heat value is determined to be 41.49 ± 1.210 J mol−1 K−1 in the temperature range from 1289 to 1850 K. The dendritic growth velocity of α-Ni solid solution phase within the liquid alloy was measured as a function of undercooling, which attains 25.4 m s−1 at the undercooling of 358 K. The rapid dendritic growth results in the significant solute trapping of all the five solutes. The lattice constant of α-Ni solid solution phase is found to increase with the extent of solute trapping. A microstructural morphology transition occurs from well-branched dendrites into equiaxed grains with the rise of undercooling.