Quantitative analysis of quench sensitivity of 7xxx alloys by using small angle X-ray scattering

Zhang, Yong, Rometsch, P., Starink, M.J., Milkereit, B., Pelliccia, D. and Kirby, N. (2016) Quantitative analysis of quench sensitivity of 7xxx alloys by using small angle X-ray scattering. The 15th International Conference on Aluminum Alloys (ICAA15), Chongqing, China. 11 - 15 Jun 2016. 4 pp .

Abstract

Different quench sensitivity behaviours for aluminium alloys 7150, 7055, 7085 and 7037 have been systematically studied by using small angle X-ray scattering (SAXS) at the Australian synchrotron. The results have shown that due to different chemical compositions, the ageing behaviour is different after different cooling paths from the solution treatment temperature. The size of ?' precipitates formed during ageing generally decreases with increasing cooling rates. The volume fraction of ?' precipitates formed during ageing increase with increasing cooling rate, indicating that more solute atoms has been retained in solution prior to ageing. For all the studied alloys, no ?' precipitates can be detected below a certain cooling rate, demonstrating that the matrix concentration is not sufficiently high for ?' precipitation during subsequent ageing. The current paper demonstrates that the SAXS technique can be used to quantitatively analyse the effect of quench rate on the size and volume fraction of ?' precipitates in 7xxx alloys in the T6 condition. Moreover, the matrix concentration and/or the chemical composition of ?' precipitates can also be characterised.

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