Effect of quenching rate on the properties of melt-spun FeNbCuSIB ribbons

Amorphous ribbons of composition Fe73.5Nb3Cu1Si13.5B9 and Fe72Nb4.5Cu1Si13.5B9 were prepared by rapid solidification technique. A convergent nozzle of suitable dimensions was chosen so as to minimise the turbulent flow of the fluid. The separation between the nozzle and the quenching wheel surface was kept constant at 0.5 mm. The quenching rate was directly proportional to the wheel velocity as the dimension of the crucible and the position of crucible with respect to wheel surface were kept fixed in all the trials. The thickness of ribbon was found to decrease while the ductility increased with the increase of wheel surface velocity, i.e. with the increase of quenching rate. The amorphous to nanocrystalline transformation temperature was found to remain constant when the wheel surface velocity was more than 32 m/s and also the soft magnetic properties were found to be superior.