Abstract: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.

Key words: Al-Mg alloy; dislocation configuration, Taylor lattice; cell structure