Grain Boundary Precipitate Modification for Improved Intergranular Corrosion Resistance

Kinga A. Unocic; Paul Kobe; Michael J. Mills; Glenn S. Daehn

doi:10.4028/www.scientific.net/MSF.519-521.327

Paper Titles

Characterisation of AlFeSi Intermetallics in 6000 Series Aluminium Alloy Extrusions
p.303

Vacancy-Solute Aggregates in Al-Zn-Mg-(Cu, Ag)
p.309

Key Microstructural Features Responsible for Improved Stress Corrosion Cracking Resistance and Weldability in 7xxx Series Al Alloys Containing Micro / Trace Alloying Additions
p.315

Development of a New 7xxx Ageing Model
p.321

Grain Boundary Precipitate Modification for Improved Intergranular Corrosion Resistance
p.327

Microstructural Interactions during Stress Ageing a 7475 Aerospace Alloy
p.333

Influence of Zinc to Magnesium Ratio and Total Solute Content on the Strength and Toughness of 7xxx Series Alloys
p.339

Microstructural Evolution of a New Aerospace 7XXX Alloy during Retrogression and Re-Ageing Treatment
p.345

Blister Free Heat Treatment of High Pressure Die-Casting Alloys
p.351

HomeMaterials Science ForumMaterials Science Forum Vols. 519-521Grain Boundary Precipitate Modification for...

Grain Boundary Precipitate Modification for Improved Intergranular Corrosion Resistance

Abstract:

Intergranular corrosion is a significant concern for Al-Mg alloys when subjected to a corrosive salt-water environment. To address this issue, the standard composition of a 5XXX series aluminum alloy (AA5083) was modified in an attempt to improve the alloy’s overall corrosion resistance through alloying and thermal processing. The concept being that through alloying and heat treatments, desirable precipitate phases such as τ- and/or τ-copper rich phase(s) that are known to offer corrosion resistance would potentially form that could effectively improve intergranular corrosion behavior. Therefore, the chemical composition of standard AA5083 was modified by adding various amounts of copper and zinc. Sensitization heat treatments were then performed to determine the specific conditions under which these phases would form. LOM, SEM, STEM imaging and conventional TEM were used to analyze microstructural features. Corrosion was attributed to a network of detrimental Mg-rich grain boundary precipitates in the standard alloy. Alloying with Cu and Zn can offer improved intergranular corrosion behavior. The mechanism seems to be either by delaying or eliminating precipitation at the grain boundaries.