摘要
为了系统研究纳米材料的超塑性变形特点,用电沉积方法制备了平均晶粒尺寸为70 nm的纳米镍.采用单向拉伸实验研究了其在室温和高温时的力学性能,并用透射电子显微镜TEM、扫描电子显微镜SEM和X射线能谱仪EDS观察分析了纳米镍变形前后的显微组织.实验结果表明:制备的纳米镍在室温时表现出的延伸率很低,但强度可达1000 MPa以上.当温度升高至450℃,应变速率为1.67×10-3s-1时单向拉伸实验得到380%的延伸率,说明制备的纳米镍具有低温超塑性性能.实验过程中,材料内部的晶粒发生明显的长大与拉长.拉伸过程中形成的氧化物夹杂成为裂纹源,断口表现为沿晶断裂.
In order to investigate the characteristic of nanocrystalline material during superplastic deformation, nanocrystalline nickel with the mean grain size 70nm was produced by electrodeposition. Tensile tests at and above room temperature were carried out to investigate the mechanical properties of electrodeposited Ni. Scanning Electron Microscope （SEM）, Transmission Electron Microscope （TEM） and Energy Disperse Spectroscopy （EDS） were employed to examine the microstructures of the as-deposited and deformed specimens. The results at room temperature showed that nanocrystalline Ni had limited elongation but high tensile strength up to 1000 MPa. A maximum elongation of 380% was observed at 450 ℃ and a strain rate of 1.67 × 10^-3 s^-1, which proved the low temperature superplasticity for nanocrystalline Ni. Grain growth and grain elongation were observed in the deformed specimen. The fracture surface appeared intergranular crack, due to the oxide formed during tensile test.
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2007年第1期35-39,共5页
Materials Science and Technology
基金
国家自然科学基金资助项目(50575049)
关键词
纳米镍
拉伸性能
断口
电沉积
nanocrystalline Ni
tensile behavior
fracture surfaces
electrodeposition
