The research of the effects of prerecovery to aluminum alloy Al-10.78Zn-2.78Mg-2.59Cu-0.22Zr-0.047Sron microstructure and properties

Abstract:

The effects of prerecovery ( 250℃×24h + 300℃×6h + 400℃×6h ) to aluminum alloy Al-10.78Zn-2.78Mg-2.59Cu-0.22Zr-0.047Sr on microstructure and properties was researched by analysis of EBSD、XRD and test of hardness、conductivity、tensile、intergranular corrosion、exfoliation corrosion. The results show that, prerecovery treatment can refine grain size with average size reduces from 7.30 μm to 5.57 μm and increase the proportion of low angle grain boundary from 0.588 to 0.623. The effect of prerecovery on hardness and conductivity of the alloy is small, but the strength of the alloy is obviously improved by the prerecovery. The yield strength of alloy at peak aging(120℃×48h) processed by prerecovery is 633.2 MPa. Compared with the alloy without prerecovery treatment, the yield strength increased by 35 MPa. The intergranular corrosion and exfoliation corrosion of alloy after prerecovery treatment are improved from rank 4 to rank 3 and rank EA to rank PB respectively.

Key words:Al-Zn-Mg-Cu aluminum alloy; prerecovery; solution; high/low angle grain boundaries; microstructure and properties