Effects of Er/Sr/Cu additions on the microstructure and mechanical properties of Al-Mg alloy during hot extrusion

- The Er, Sr and Cu additions have considerable influences on the morphology of the Al3Fe phase in the as-cast Al-Mg alloy.
- The mechanism of grain refinement and coarsening has been investigated.
- The Er, Sr and Cu additions refine the grain of the as-extruded Al-Mg alloy.
- The incompletely recrystallization occurs in the Al-Mg alloy with Er addition.
- The different hardness distribution are presented in the as-extruded alloys.

The effects of Er/Sr/Cu additions on the microstructure and mechanical properties of Al-Mg alloy during hot extrusion were studied by using metalloscope, scanning electron microscope, differential scanning calorimetry, stretcher, hardness tester, linear intercept method and equivalent area method in this paper. Experimental results show that, after hot extrusion, the second phases in the whole alloys have been broken into fine particles along the extrusion direction. All of the alloys are composed of fine recrystallized grains except the Al-Mg-Er alloy. Er, Sr and Cu additions can refine the grain size and improve the distribution homogeneity of the grains and increase the ultimate tensile strength, elongation to failure and hardness of Al-Mg alloy. The hardness value which is perpendicular to the longitudinal section of the as-extruded alloys gradually decreases from surface to center of all the alloys from surfce to center except the Al-Mg-Er alloy which firstly decreases and then increases, indicating that the deformation is non-uniformly during the hot extrusion.