Effect of Aging Regime on Microstructure and Mechanical Properties of 2195 Al-Li Alloy

The microstructure and mechanical properties of 2195 Al-Li alloy under different aging regimes were analyzed by hardness test, tensile test and transmission electron microscopy. The results show that the peak aging regimes of single stage aging are 160 degrees C/56 h and 190 degrees C/16 h, of which the peak tensile strength is 565 and 541 MPa, and elongation is 6.3% and 7.1%, respectively. The tensile strength and elongation of the alloy aged at 190 degrees C/4 h+160 degrees C/32 h are 588 MPa and 13.5%. Both of them are much better than those of the single-stage aging alloys. The elongated T-1 phase and compact region in the double stage aging alloy matrix play an important role in improving the strength. In addition, the narrow precipitation free zone along grain boundary and the cell structure inside grains are the main factors for the performance enhancement of plasticity. The double stage aging regime of 190 degrees C/4 h+160 degrees C/32 h can obtain better comprehensive mechanical properties than single stage aging.