Solidification microstructure in a supercooled binary alloy

Abstract The maximum undercooling that has been achieved for Ni-Cu alloy, by using molten glass purification and cyclic super-heating technology, is 270 K. With the help of high-speed photography, solidification front images alloy at various typical were obtained. Two grain refinements occurred in range 60 K< ΔT < 100 K > 170 K, became smoother, position appeared randomly. increase undercooling, transition from solute diffusion to thermal leads coarse dendrite directional fine dendrite. At large considerable stress accumulated some dislocations exist microstructure. However, proportion high-angle boundaries as high 89%, with twin 13.6% most strain-free structures, microhardness decreases sharply. This indicates causes plastic strains microstructure, later stage recalescence, part dissipated system acts driving force promote recrystallization