Structure and consolidation of rapidly solidified Meso 10 alloy flakes

Hot compression tests were carried out on rapidly solidified (RS) and KOBO-extruded Meso 10 alloy (AA7000 series), in a range of temperatures between 293 K and 773 K. The flow stress was higher than that of as-extruded industrial 7N01 alloy with a composition close to AA7039. Structural observations revealed an uncommon structure of the rapidly solidified Meso 10 alloy. Fine Zn-rich particles, 20-180 nm in size, were observed in RS-flakes. The crystallographic structure of the particles does not resemble the structures of eta', eta, or T-phases that are commonly reported for age-hardenable AA7000 series alloys. Hot deformation and prolonged ageing of as-extruded material result in a transformation of the RS structure into one that is typical for AA7000 series alloys. For comparison, structural observations on RS-material produced by commonly used direct hot-extrusion that involves the preheating of the charge at 673 K were also performed. Effect of the processing path on materials properties is discussed. (C) 2010 Elsevier B.V. All rights reserved.