中文摘要：

采用直流电解沉积技术制备出具有高密度择优取向的纳米孪晶结构块体纯Cu样品.利用XRD,SEM和TEM等手段研究了添加剂浓度对其微观结构的影响.结果表明,样品由沿沉积方向生长的微米尺寸柱状晶粒构成,晶粒内含有高密度孪晶界,且大部分孪晶界平行于生长表面.添加剂（明胶）浓度对纳米孪晶Cu的孪晶片层厚度有明显影响,但对晶粒尺寸影响不大.无添加剂时,纯Cu样品中存在微米量级宽大孪晶片层,当添加剂浓度从0.5 mg/L增加到5 mg/L,孪晶片层厚度从150 nm减小至30 nm,且孪晶界生长更完整.其原因是随着添加剂浓度增加,阴极过电位增大,孪晶界形核率增加,从而使孪晶片层厚度减小.

英文摘要：

Nanotwinned metals have attracted widespread attentions recently, due to their unique overall properties, such as high strength, considerable ductility, enhanced work hardening and high electrical conductivity. The method of synthesized nanotwinned metals is an essential factor for influencing its application. To date, the di- rect-current electrodeposition technique is successfully used to fabricate bulk nanotwinned Cu samples. However, many parameters, such as the density of current, additive, the concentration of Cu2＋, pH and temperature, influence the formation of nanoscale twins during electrodeposited process. To understand the effect of electrolyte additive on the formation of twins, in this work, gelatin with different concentrations was added into the electrolyte while other parameters are kept invariant. Bulk Cu with preferentially oriented nanoscale twins was synthesized in CuSO, electrolyte with different concentrations of gelatin. The nanotwiuned Cu sample is composed of columnar grains with high density nanoscale coherent twin boundaries, most of them are parallel to the growth surface. It is foundthat the concentration of the electrolyte addition plays an important role in the twin lamellar spacing of the nanot- winned Cu samples, but has little effect on grain size. No twins or twins with micro-sized spacing are detected in electrodeposited Cu without the electrolyte addition. With the concentration of gelatin increasing from 0.5 mg/L to 5 rag/L, the average twin lamellar thickness of the bulk nanotwinned Cu samples decreased from 150 nm to 30 nrn. Twin boundaries also grow longer in grains with the increase of gelatin. This is because that with the increase of the concentration of gelatin, the overpotential of cathode increases and nucleation of twins becomes easier, result- ing in the reduction of twin spacing.