OCC技术制备的单晶铜线材冷拔组织TEM分析

TEM Analysis of Drawn Single Crystal Copper Wires Produced by OCC Method

采用TEM系统分析了OCC技术制备的单晶铜线材在冷拔过程中形成的位错胞、几何必须界面以及孪晶,发现当真应变小于0.94时,冷拔单晶铜线材的微观组织为位错胞。当真应变大于0.94时,其微观组织主要包括位错胞和几何必须界面两类组织。其中位错胞沿冷拔方向拉长,横界面上为等轴状。随变形量的增加,位错胞尺寸减小,当真应变大于1.39时,位错胞尺寸不再随塑性变形量的增加而减小,其直径保持在0.28μm左右。当变形量比较小时,两类几何必须位错界面属于晶体学界面,当变形量比较大时,几何必须位错界面与冷拔方向平行。同时,分析还发现冷拔单晶铜线材中存在少量由凝固过程形成并遗传到形变组织以及在冷拔过程直接形成的两类孪晶。

Dislocation cells, geometrically necessary boundaries （GNB） and twins in drawn single crystal copper wires produced by Ohno continuous casting （OCC） method have been analyzed by TEM. The results show that when the strains are lower than 0.94, the microstructures of drawn single crystal can be characterized as dislocation cells. When the strains are more than 0.94, there are two kinds of microstructures. One is that dislocation cells are elongated in longitudinal section and equiaxed in cross section. The size of dislocation cells decreases as the strain increases until they reach a critical size of about 0.28 /.tm at a strain of 1.39. The other is geometrically necessary boundaries. At low strains, two kinds of geometrically necessary boundaries are along { 111 }, and at high strains, geometrically necessary boundaries are parallel to drawn direction. In addition, it is found that in dawn single crystal copper wires, there are two types of twins in the single crystal copper wires. One is formed in the preparing process of single crystal copper wires by Ohno continuous casting method, and the other is formed during cold drawing deformation.