摘要
采用透射电镜研究Er和Yb元素对二元Al-Mg合金位错分布组态的影响。研究结果表明:二元Al-Mg合金挤压态的位错组态呈典型的"Taylor晶格"分布,但经拉伸变形至断裂后,合金中储存的高应变能可以抵消Mg原子对位错运动的阻碍作用,使部分位错发生束集而产生交滑移,最终形成胞状组织。添加Er元素不改变Al-Mg合金的位错组态,无论是经挤压还是经拉伸变形至断裂后,含Er的Al-Mg合金均具有与二元Al-Mg合金类似的位错分布组态。添加Yb元素可明显地改变Al-Mg合金的位错分布组态。即使在变形量较小的挤压态,位错也不呈准均匀的"Taylor晶格"分布,而是表现出胞状组织的特征。当添加0.3%(质量分数)的Yb时,Al-Mg合金中形成了高密度位错墙;而当添加1.0%的Yb时,合金中形成了明显的胞状组织。Yb原子通过与Mg和Al原子形成脆性化合物,降低了Mg在基体中的固溶度,从而抑制Mg原子对位错运动的阻碍作用。
The effects of Er and Yb elements on the dislocation distributions of a binary Al-Mg alloy were studied using a transmission electron microscope（TEM）.It is shown that the as-extruded dislocation distributions of the binary Al-Mg alloy show typical ＂Taylor lattice＂ configurations,while the dislocation distributions of the binary Al-Mg alloy after the tensile testing to fracture show cell structures since the stored high deformation energy can effectively decrease the inhibition of Mg atoms on the dislocation movements.The addition of Er element cannot change the dislocation distributions of the Al-Mg alloy.The dislocation distributions in Er-containing alloy show similar characteristics to the binary Al-Mg alloy,no matter whether the alloy is in extruded state or after tensile testing to fracture.However,the addition of Yb element can obviously change the dislocation distributions of the Al-Mg alloy.Even under low deformation degree,such as in the as-extruded stage,the dislocation distributions show the features of cell structure,instead of the quasi-uniform distributed ＂Taylor lattice＂.When 0.3%（mass fraction） Yb is added into the alloy,the dislocation walls with high density dislocations are formed in the matrix,and when 1.0% Yb is added into the alloy,the cell structures are formed obviously in the alloy.Yb atoms,combined with Mg and Al atoms,form brittle compounds in the alloy,decrease the solid solution degree of the Mg atoms in the Al matrix,and thus decrease the inhibition of the Mg atoms on the dislocation movements.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2011年第1期66-71,共6页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(50831007
50823006)
