Effect of undercooling on microstructure evolution of Cu based alloys

Based on the deep undercooling rapid solidification method, the Cu based alloy has reached different un-dercooling degrees. The microstructure and evolution of non-equilibrium solidification of two alloys were systematically studied. It is found that grain refinement occurs in both the large undercooling range and the small undercooling range of the two alloys. EBSD technology was used to analyze the grain refinement structure, and the results showed that the grain refinement structure with large undercooling and that with small undercooling had completely different grain orientations. The grain refinement of low undercooling alloy is caused by dendrite remelting and fragmentation, while that of high undercooling alloy is completed by stress induced recrystallization. The evolution law of undercooling and microstructure hardness was systematically studied by using a microhardness tester. It was found that a sudden drop in grain size oc-curred near the critical undercooling, which is the direct evidence of grain refinement of non-equilibrium solidification structure of high undercooling alloy due to recrystallization.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Using the deep undercooling rapid solidification method, Cu based alloy was studied at different undercooling degrees. It was found that grain refinement occurred in both large and small undercooling ranges for the two alloys. EBSD analysis showed that the grain refinement structures differed in grain orientations for large and small undercooling. The refinement mechanisms were dendrite remelting and fragmentation for low undercooling alloy, and stress-induced recrystallization for high undercooling alloy. A sudden drop in grain size near critical undercooling was observed for the high undercooling alloy, providing direct evidence of grain refinement due to recrystallization in non-equilibrium solidification structure.