EFFECTS OF STATIC MAGNETIC-FIELD ON UNDERCOOLING OF A COPPER MELT

The effects of static magnetic field (5000 Oe) were investigated on undercooling of a copper melt in glass slag. The procedure of melting and solidifying was repeated 13 times in each sample. The thermal analysis curves for ten samples (five samples in the presence of magnetic field and five samples in the absence of magnetic field) were measured during every melting-solidifying cycle and the degree of undercooling was obtained in every cycle. The undercoolings of all samples increased in a few numbers of early cycles and after about six cycles they were almost saturated and independent of cycle number. Irregular and unexpectedly large decreases of undercooling sometimes appeared. Two remarkable effects of magnetic field on undercooling were found. One is that the maximum undercooling in the presence of a magnetic field is apparently higher than that in the absence of a magnetic field for every sample. The second is that the application of magnetic field tends to suppress the irregular and unexpectedly large decreases of undercooling. These results are discussed in respect of the thermodynamic effect (the magnetic free energy change on solidification) and the magnetohydrodynamic effect (the suppression of thermal convection).