温度对电沉积纳米孪晶Ni显微结构及纳米压痕力学性能的影响

EFFECT OF TEMPERATURE ON MICROSTRUCTURE AND NANOINDENTATION MECHANICAL PROPERTIES OF ELECTRODEPOSITED NANO-TWINNED Ni

在镀液成分、pH值、沉积电流密度和脉冲占空比等工艺参数不变的条件下,利用脉冲电沉积技术在镀液温度分别为30.50和80℃时制备了包含高密度纳米孪晶片层结构的纳米晶Ni薄膜.利用SEM,XRD和TEM研究了镀液温度对纳米孪晶Ni薄膜的沉积速率、择优取向、晶粒尺寸、孪晶片层特征尺寸(长度和厚度)以及生长规律的影响;利用HRTEM揭示了纳米孪晶Ni的孪晶界面微观结构特征,利用纳米压痕技术研究了温度对Ni薄膜纳米压痕硬度的影响.研究结果表明:脉冲电沉积纳米孪晶Ni薄膜的生长速率在20—30 nm/s之间,镀液温度为30和50℃时Ni薄膜沿(220)面择优生长,80℃时转变为沿(200)面择优生长;随着镀液温度的升高,Ni薄膜的平均晶粒尺寸由900 nm减小到300 nm,晶粒内部孪晶片层的厚度由60 nm降低到28 nm;50℃时纳米孪晶Ni薄膜的纳米压痕硬度平均值最高,达3.75 GPa.

The nanocrystalline nickel thin films with high density nano-scale growth twins were synthesized by means of pulse electrodeposition technology. Three samples were deposited at different bath temperatures of 30, 50 and 80 ℃, by keeping all the other parameters as constant, such as electrolyte, pH value, current density and on-time and off-time period. The effect of temperature on deposition rate, sample texture, grain size, and twin boundary length and twin lamella thickness were systematically analyzed by SEM, XRD and TEM techniques. The microscopical feature of twin boundary were investigated by HRTEM. The results show that the nano-twinned nickel films deposited at the rates ranging from 20 nm/s to 30 nm/s have a preferred growth plane of （220） when deposited at 30 and 50 ℃, but changes to （200） when the temperature increases to 80 ℃. With increasing temperature, the grain size decreases from 900 to 300 nm, and the twin lamella tnlcl〈ness aecreases from 60 to 28 rim. The relationship between deposition temperature and nanoindentation hardness for these films, moreover was determined. The nanoindentation hardness measurement indicates that the average indentation hardness of these films reaches a maximum value of 3.75 GPa at 50 ℃.