Effect of dynamic recrystallization on healing at pure nickel joint interface during hot compression bonding
In order to study the relationship between the microstructural evolution and the healing effect of the joint interface during hot compression bonding,the unidirectional hot compression was carried out with pure nickel bars.Different types of discontinuous dynamic recrystallization were triggered by the combination of different temperature and strain-rate.By mechanical test together with microstructural examination after hot compression,it was found that the mechanism of boundary bulging is more likely to work under the combination of temperature as high as 1100℃and strain-rate as low as 0.001 s-1,resulting in the significant migration effect of the joint interface for better healing quality.On the contrary,the mechanism of sub-grain coalescence will dominate gradually with the temperature as low as 800℃combined with the strain-rate as high as 0.01 s-1,which has relatively weak migration effect of the joint interface and thus corresponding to the low healing quality.Initial analysis by sub-grain coalescence model combined with multi-phase field method indicates sub-grain coalescence can only eliminate small angle grain boundaries effectively,the big angle grain boundaries similar to joint interface remain very stable both in structure and position during recrystallization.
hot compression bonding(HCB)discontinuous dynamic recrystallizationhealing at joint interfacenucleation type of recrystallizationmulti-phase field method
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