Effect of Heat Treatment Temperature on Microstructures and Mechanical Properties of 2519A Aluminum Alloy

The influence of ageing temperature on the microstructures and mechanical properties of 2519A aluminum alloy was investigated by hardness test,tensile test,transmission electron microscope(TEM) and scanning electron microscope(SEM).Results show that,after being aged at 140 ℃ for 9 h,there was a few precipitation of finely dispersed θ′ phase in a form of flake within grains,while grain boundary precipitation of θ′ phase was fine and in a chain-like distribution,with a narrow precipitation-free zone(PEZ) along grain boundaries,resulting in strength of aluminum alloy being lower.After being aged at 165 ℃ for 9 h,finely dispersed θ′ phase precipitated within grains was generally strengthened,while grain boundary precipitation of θ′ phase was discontinuously distributed,with a narrow PEZ along grain boundaries,resulting in the strength of alloy obviously improved.After being aged at 190 ℃ for 9 h,less θ′ phase was precipitated within grains,while grain boundary precipitation was coarse and distributed continuously along grain boundaries,with a wider PEZ on the both sides of precipitated phase,resulting in the strength of alloy being lower.