Mechanical consolidation of rapidly solidified Meso 20 alloy flakes – Structure and mechanical properties

Abstract

The mechanical properties and microstructure evolution of the rapidly solidified (RS) Meso 20 aluminum alloy, followed by mechanical consolidation of RS-flakes were investigated. Specimens of as-extruded material and the specimens solution treated at 773K/30min were tested in hot compression at temperatures ranging from 293K to 773K. It was found that the flow stress was reduced monotonically with deformation temperature within the used deformation temperature range. Expected dynamic precipitation hardening at the intermediate deformation temperatures for solution treated specimens was negligible. Concurrently, the crystallographic structure and the distribution of the particles did not correspond to the commonly known morphology of the highly disperse η′, η precipitates and Al6Mn particles that are usually reported for the industrial AA7000 series alloys. Due to the low-temperature extrusion method, most of the fine Mn-rich particles retained their quasicrystalline structure formed during the rapid solidification and following consolidation of the RS-flakes. The solution treatment of the as-extruded specimens at 773K/30min was found to result in the development of μ-Al4Mn rod-like particles. The twinned structure of the particles points to their growth along 〈3 3¯ 0 1〉 direction.