Effects of Sc,Er and Be Compound Addition on Microstructure and Properties of Al-Zn-Mg-Cu Alloy
The effects of compound addition of Sc,Er,and Be on the microstructure and properties of Al-8.3Zn-2.2Mg-2.3Cu alloys were investigated using optical microscope(OM),electron backscatter diffraction(EBSD),scan-ning electron microscope(SEM),transmission electron microscope(TEM),and Vickers hardness test methods.The results indicate that the addition of Sc,Er,and Be elements can increase the proportion of low angle grain boundaries to 56.2％,effectively reducing the transition from low angle grain boundaries to high angle grain boundaries in the alloy,and the alloy presents little preferred orientation.After T6 treatment,large amounts of spherical Al3Sc disper-soids are observed within the alloy and at grain boundaries,accelerating the precipitation of η'while hindering grain boundary and dislocation movements.The addition of Be plays a role in solid solution strengthening.Additionally,par-tial Be exists in the form of α-Be,while another portion forms a Be-containing second phase at the grain boundaries.The hardness of the alloy in T6 state is 240.6 HV.
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