Three-Stage Homogenization of Al-Zn-Mg-Cu Alloys Containing Trace Zr

Under various homogenization conditions, the precipitation behavior of Al3Zr dispersoids and its effects on the microstructures and tensile properties of an Al-7.8Zn-1.62Mg-1.81Cu (AA7085) alloy with zirconium addition within the AA7085 composition standard were investigated in the current study. It was found that a three-stage homogenization [723 K (450 A degrees C)/12 h, 623 K (350 A degrees C)/8 h, and 753 K (480 A degrees C)/12 h] enhanced the uniformity of the Al3Zr dispersoid distribution, revealing that a large number of pre-precipitated MgZn2 dispersoids with diameters less than one micrometer were favorable nucleation sites for the Al3Zr dispersoids. The uniform distribution of Al3Zr dispersoids reduced recrystallization during hot-rolling and solution heat treatment, improving the tensile properties of the as-aged sample by 6.5 pct. DOI: 10.1007/s11661-013-1639-5 (C) The Minerals, Metals & Materials Society and ASM International 2013