Effects of current stressing on microstructure and properties of Cu36Zn alloy

Abstract

This study discussed the mechanism of properties change on Cu36Zn alloy after current stressing through the investigation of microstructure and mechanical properties The strip specimens were subjected to 10000~16000 A/cm2 D C for 2h-5cycles and then were rapidly quenched with liquid nitrogen after current stressing to freeze the microstructure for investigation The results show that the extent of variation of sheet resistance and micro-hardness kept increasing with the increase of current density The activation energies of micro-hardness change calculated via Arrhenius equation were 23 9kJ/mol for low current density (10000~13000 A/cm2) and 3 6kJ/mol for high current density (13000~16000 A/cm2) EBSD analysis indicated that the recrystallization was accompanied by an increase of small grain fraction and twin fraction when the specimen was stressed under low current density The uncompleted recrystallization behavior is likely ascribed to generation of dislocation induced by electron wind force The newly formed dislocations act as the nucleation sites for recrystallization The current-induced Joule heat facilitates the recrystallization behavior Grain boundary effect will affect the properties but the change of grain size is not obvious So strain field effect is still the main mechanism of properties change under low current density HRTEM analysis indicated that more dislocations were produced in the specimen at high current density the dislocation density increased abruptly up to 1017 m-2 The properties change under hugh current density is ascribed to strain field effect

Date of Award	2019
Original language	English
Supervisor	Kwang-Lung Lin (Supervisor)