Abstract: One,two and three recalescence events in the solidification of highly undercooled Ni_68B_21Si_11 alloy melt and the conditions of undercooling together with the effect on solidification morphologies were revealed.The solidification morphologies of the undercooled alloy may be examined in the light of two aspects,i.e,growth of either Ni_3B,Ni_6Si_2B and Ni_2B ternary eutectic or dendrite cluster with Ni_3B as leading phase.When the degree of undercooling below 200 or over 310 K,the alloy solidifies to accompany one recalescence only, and the crystals grow according to the first mode of solidification.While undercooling at other temperatures,two or three events of recalescence may occur and the dendrite cluster may so- lidify.

Key words: recalescence event, undercooling, X-ray analysis