Cu-Nb复合线材在形变与退火过程中显微结构演变的研究

STUDY ON THE MICROSTRUCTURE EVOLUTION OF Cu-Nb COMPOSITE WIRES DURING DEFORMATION AND ANNEALING

采用SEM和TEM,对不同形变量及退火温度下的Cu-Nb微观复合线材的显微组织结构进行了分析,并对形变和退火试样进行了硬度测试.结果表明:随着形变量增大,材料界面密度及其增加速率逐渐增大.当材料结构达到纳米尺寸时(应变=24.8),界面密度及其增加速率显著增加,使得硬度及其增加速率明显增大,同时伴随有纳米Cu基体内部层错和旋转晶界的产生.退火过程中Cu基体的显微组织变化表现出明显的多尺度效应,其变化可分为3个阶段:微米及亚微米Cu基体先发生回复再结晶,而纳米Cu基体回复再结晶受到抑制;纳米Cu基体回复再结晶;Nb丝球化及长大.

Microstructure of as-deformed and annealed Cu-Nb composite wires were investigated by SEM and TEM. Hardness of the as-deformed and annealed samples were measured. The results showed that both the in- terface density and the rate of interface-increasing increased with increasing strain. When the microstructure reached nano-scale （strain=24.8）, the interface density showed a sharp increase which induced a rapid increase in hardness, accompanied by formation of stacking faults and rotation grain boundaries in Cu. During the annealing, the size effect impacted the evolution of microstructure of the multi-scale Cu matrix. The evolution can be classified in to three stages with respect to annealing temperatures： recovery and recrystallization of large Cu, while that of the nano Cu were restrained; recovery and recrystallization of nano Cu; spheroidization and coarsening of Nb.