Abstract: The structural evolution of undereooled single-phase Ni-2wt%Pb monotectic alloy wassystematically investigated by using the method of molten glass denucleating combinedwith superheating cycle. Within the achieved undercooling range of 22 to 280K, thesolidification structure undergoes three changes at 22K, 88K and 187K, respectively.With the increase of undereooling, common dendrites, the first class granular grains,undercooled dendrites and the second class granular grains come out one after theother. Analytical results show that the granulation mechanism of the first class gran-ular grains is owing to dendrite remelting and recrystallization, and the second isowing to dendrite break-up and recrystallization.

Key words: undereooling, monotectic alloy, structural evolution, granulation mechanism