Quantitative Investigation on Nano-Scale Precipitates in an Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr Alloy under Various Aging Tempers

Abstract:

In the present study, a systematic study of nanoscale precipitates in an Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr alloy have been carried out for various typical aging tempers, including T6, T76, T74, T73 and RRA treatments, by combining synchrotron-based small-angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) techniques. Based on the TEM observations, quantitative and statistical structural information, including precipitate size, volume fraction, number density and inter-precipitate distance have been extracted from SAXS data through model fitting. The results show that the T6 peak-aged alloy with the smallest precipitate size has the highest number density and lowest volume fraction of precipitates. Under two-step T7X over-aged tempers, with the deepen of aging degree, the precipitate size, volume fraction and inter-precipitate distance increases, but the number density decreases. The size distribution of precipitates for the RRA-treated alloy is in between that of T6 and T76. The results also show that as the degree of over-aging deepens, the precipitate size distribution interval becomes broader.

• Periodical: Materials Science Forum (Volumes 783-786)
• Pages: 210-215
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.783-786.210
• Online since: May 2014
• Authors: Bai Qing Xiong*, Dong Mei Liu, Zhi Hui Li, Xi Wu Li, Yon Gan Zhang, Feng Wang, Hong Wei Liu
• Keywords: Aging, Aluminium Alloy, Precipitate, Small-Angle X-Ray Scattering

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