标距尺寸对纳米镍拉伸性能的影响

The Effect of Gauge Dimension on Tension Properties in Nanocrystalline Ni

采用直流电沉积制备了平均晶粒尺寸为27.2 nm且宽晶粒尺寸为5~120 nm的纳米镍.通过室温单向拉伸实验研究了标距尺寸对纳米镍力学性能的影响.研究发现,纳米镍的屈服强度随标距长宽比(r)的增加而增加,弹性、塑性应变均随r的增加而减小,标距尺寸对拉伸中的剪切断裂行为没有影响;通过TEM对拉伸断口、剪切带组织的观察,发现纳米镍变形后平均晶粒尺寸较镀态下具有明显粗化,剪切带是由变形过程中首先粗化的晶粒区发生进一步的集中塑性变形引起的,剪切带上晶粒沿特定方向被拉长,平直的晶界对应于SEM观察到的平行线.

The nanocrystalline(nc) Ni with an average size of 27.2nm and a broad grain size distribution ranged from 5nm to 120 nm was prepared by direct current electrodeposition.Effects of the gauge dimension in tension specimen on mechanical properties and behaviors were performed by uniaxial tension test at room temperature.It was found that yielding strength increases,while elastic and plastic strain decrease with increasing aspect ratio of gauge dimension.However,the gauge dimension has never influenced the shea...