Effect of solution treatment on microstructures, properties and fractography of Al-9.8Zn-2.37Mg-2.22Cu aluminum alloy

Effects of solution treatment parameters on microstructures, tensile properties and fractography of Al-9.8Zn-2.37Mg-2.22Cu-0.12Zr alloy were studied by tensile testing, optical microscopy, SEM and EDS. The tensile testing and optical observation indicated that the insufficient solution time and lower solution temperature were not beneficial to the re-solution of soluble second phase particles into the matrix and increase the strength of the alloy after artificial ageing. The samples over-burned easily for too high solution temperature and long excessive time. The results of EDS showed the re-solved particles were AlZnMgCu type compounds containing Fe survived during solution treatment. It is found that the tensile fractography was affected by the volume fraction of residual particles and the recrystallization level of deformed grains.