Thermomechanical ageing (TMA) of 2014 aluminium alloy for aerospace applications
Various thermomechanical ageing (TMA) treatments for 2014 Al-alloy have been developed which include partial peak ageing, warm rolling and further ageing to peak hardness at 160°C. Electron microscopic studies reveal that the TMA treatments affect substantially the ageing characteristics. The TMA-Ib treatment yields finestϑ′ needles having longitudinal dimensions of ∼400 Å. TMA treatment leads to precipitate-dislocation network of different magnitudes. Among the TMA treatments, the TMA IIb treatment results in thickest precipitate-dislocation tangles. In addition toϑ′, two types of dispersoids Al4CuMg5Si4 and Al12 (Fe, Mn)3Si have been observed. The density or concentration of these dispersoids is drastically reduced due to TMA treatments. Thus an optimum TMA treatment i.e. TMA-IIb has been developed which results in a significant improvement in the mechanical properties of 2014 Al-alloy.
KeywordsThermomechanical ageing 2014 aluminium alloy
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