ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A systematic study of the precipitation processes in high strength Al-Zn-Mg-Cu alloyshas been conducted. A series of experimental alloys was prepared with varying Zn:Mg ratio, butequivalent total solute content, to be representative of those used in applications which demand acombination of strength, fracture toughness and resistance to environmentally sensitive crackingmechanisms. Artificial ageing curves were constructed for each alloy, based upon 7xxx seriesduplex treatments widely used in industry. Ageing kinetics were investigated beyond peak strengthinto the overaged condition, since this is known to promote the most favourable balance ofproperties. Differential scanning calorimetry (DSC) and transmission election microscopy (TEM)observations were made on the alloys throughout the ageing process to fully understand theprecipitation events occuring. For a particular overageing treatment, higher Zn:Mg ratio alloys wereconsistently found to be at a more advanced stage of precipitation while higher strengths wereretained at low Zn:Mg ratios. Grain boundary characteristics, such as particle size and precipitatefree zone width, were also influenced by Zn:Mg ratio at a given strength level. This paper providesnew understanding of precipitation kinetics and the control of important microstructural featureswhich influence the balance of properties in 7xxx series aluminium alloys
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.519-521.339.pdf
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