The microstructural evolution and phase transformation behavior of a designed multiphase Ni3Al-based superalloy in as-cast and spray casting states were investigated under thermal exposure at various temperatures. For the exposure temperatures range from 600 ��C to 900 ��C, the average size of ����� precipitates in the dendritic dual (��+�����) areas of the two states alloys increases, and the morphology of ����� changes to irregular shapes due to merging of neighboring particles and Ostwald ripening. After thermal exposure at 600 ��C or 900 ��C, bulky ����� precipitates generate in the interdendritic regions of as-cast alloy, and the ����� envelope develops a curved interface by aggregation. For the spray casting sample, high density of microtwins in ����� precipitates are ���inherited��� from the preceding L10-type martensite phases after thermal exposure at 600 ��C. However, the ����� precipitates without any microtwins form after thermal exposure at 900 ��C.