Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy. (22nd June 2015)

• Record Type: Journal Article
• Authors: Khushaim, Muna; Boll, Torben; Seibert, Judith; Haider, Ferdinand; Al-Kassab, Talaat
• Other Names: Jung Jan A. Academic Editor.
• Is Part Of: Advances in condensed matter physics. Volume 2015(2015)
• Publication Date: 2015-06-22
• Subjects: Condensed matter -- Periodicals; Condensed matter; Periodicals; 530.41
• DOI: 10.1155/2015/647468
• Languages: English
• ISSNs: 1687-8124

Abstract

Abstract : The microstructure of the commercial alloy AA2195 was investigated on the nanoscale after conducting T8 tempering. This particular thermomechanical treatment of the specimen resulted in the formation of platelet-shapedT 1 Al 2 CuLi / θ ′ Al 2 Cu precipitates within the Al matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. Theθ ′ platelets, which are less than 2 nm thick, have the stoichiometric composition consistent with the expected Al2 Cu equilibrium composition. Additionally, the Li distribution inside theθ ′ platelets was found to equal the same value as in the matrix. The equally thinT 1 platelet deviates from the formula (Al2 CuLi) in its stoichiometry and shows Mg enrichment inside the platelet without any indication of a higher segregation level at the precipitate/matrix interface. The deviation from the (Al2 CuLi) stoichiometry cannot be simply interpreted as a consequence of artifacts when measuring the Cu and Li concentrations inside theT 1 platelet. The results show rather a strong hint for a true lower Li and Cu contents, hence supporting reasonably the hypothesis that the real chemical composition for the thinT 1 platelet in the T8 tempering condition differs from the equilibrium composition of the thermodynamic stable bulk phase.