Effect Of Deformation And Aging Process On Properties And Microstructure Of The Al-4.9Cu-0.49Mg(wt.%) Alloy

Al-Cu-Mg alloy has been widely used in aerospace and military fields because of its advantages such as high strength,good thermal stability and excellent resistance fatigue crack growth performance.Using scanning transmission electron microscopy?STEM?,electron backscatter diffraction?EBSD?,microhardness test,room temperature tensile test and other modern analysis and experimental methods,the effects of different deformation and aging processes on the microstructure and mechanical properties of the Al-4.9Cu-0.49Mg?wt.%?alloys were systematically studied.The relationship between microstructure and mechanical properties was also discussed,which has certain guiding significance for the design of lightweight alloying and the choice of different processing.The main results are as follows:?1?After the small deformation and aging at 180?,lots of ? phases precipitates in the AlCuMg alloy,and the main precipitation phase changes from the single ? ' phase to the ?phase and ?' phase,as compared with T6 samples.?2?During subsequent aging 160?,double hardness peaks appear in the AlCuMg alloy with the large deformation treatment,and the hardness of the alloy keeps at a high level and is not easy to decline with the aging time extending.The strength values of the samples with the same strain are almost the same at the first peak hardness state?5h?and the second peak hardness state?5h?.The tensile properties of the 50%-peak ??10h?samples are the best,and ?_b,?_0.2 and ?%are 555MPa,513MPa and 6.83%,respectively.?3?After the 50%pre-deformation and aging at 160 ?,the main precipitates of the peak??5h?samples are ?' phase,and the content of the ? precipitates is small.At this time,the main strengthening terms are the dislocation strengthening and precipitation strengthening from the 0 'phase.For the peak ??10h?samples,the percentage of the ?' phase is dramatically reduced,and the thickness of the ?' phase increases obviously,but the ? phase with the large aspect ratio becomes the dominated precipitates,and the precipitation strengthening effect becomes obvious.?4?The pre-deformation and aging at 180? greatly improves the strength of the AlCuMg alloy.The strength of the 50%+180?/4h samples reached the highest value,and ?_b,?_0.2 and ?%are 570MPa,539MPa,6%,respectively.?5?The aspect ratio of ? plates with the habit of {111}_Al is larger than that of the ?'phase,and its strengthening effect is much larger than that of the ?' phase.For the samples with the 50%pre-deformation plus peak value ageing at 180?,The strength increment of the per 1%volume fraction of the ? precipitates is 38.14MPa higher than that of the ?'precipitates.