Microstructure Evolution and Mechanical Properties of 2219 Al Alloy During Aging Treatment

Hardness and tensile properties of 2219 Al alloys were tested at various temperature (150, 165, 175 A degrees C) and subjected to T6 temper heat treatment to identify the peak aging time at various temperature. Microstructure evolution and precipitate behavior were analyzed with transmission electron microscope (TEM), differential scanning calorimetry (DSC) and x-ray diffraction (XRD). It is found that the peak aging time is 24 h at 150 A degrees C and does not vary down to 165 A degrees C. When the aging temperature rise to 175 A degrees C, the peak aging time down to 12 h. Considering the strength and elongation, the optimum aging treatment is at 165 A degrees C for 24 h after the solution treatment at 535 A degrees C for 1.5 h. Compared with that of only water-quenched sample, after aged at 165 A degrees C for 24 h, the tensile strength of the 2219 Al alloy increases from 324.5 to 411.8 MPa, yield strength from 168 to 310.8 MPa, respectively. The improvement in the mechanical performance is mainly attributed to the precipitation strengthening of the GP zones, theta aEuro(3) and theta' phases.