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Effects of Ti-Ce refiners on the solidification structure and the hot ductility of Fe-36Ni invar alloy were investigated,the corresponding mechanisms were also discussed.The results showed that the solidification of the alloy was remarkably refined with the addition of 0.05%Ti-0.01%Ce refiners.Not only did the columnar grains become shorter and thinner,but the growth pattern of them changed into staggered growth from linear growth.The alloy had a bad hot ductility below 1050 °C,which was mainly attributed to weaker boundaries and the presence of grain boundary sliding.However,the hot ductility of the alloy was highly enhanced at 850-1000 °C as the addition of 0.05%Ti-0.01%Ce refiners could refine grain sizes,thus hinder grain boundary sliding,strengthen the grain boundary and promote the grain boundary movement.The alloy had a good hot ductility over 1050 °C,dynamic recrystallization occurred and was found to be responsible for the better hot ductility.In addition,the average coefficient of thermal expansion of the alloy decreased a little with the addition of 0.05%Ti-0.01%Ce refiners,which met the requirement of material properties.