Abstrakt
The aim of the experiments was to study the influence of the rolling reduction (39, 87, and 96%) on the size and distribution of secondary particles and recrystallization behaviour of Al-Mn sheets with Zr addition prepared by twin-roll casting (TRC) in the industrial conditions. Samples, cold rolled on a laboratory mill, were subjected to a two-step precipitation annealing.
Their microstructure (grain structure, substructure, particle analysis) as well as mechanical and physical properties (microharclness, electrical conductivity, resisitivity) were then characterized. The material cold worked with 39% reduction shows a moderate decrease of microharclness clue to recovery, while sheets cold worked with 87 and 96% reduction soften more clue to recrystallization.
Regardless of the cold rolling reduction, the highest density of precipitates of ec-Al(Mn,Fe)Si phase form during heating to 450 degrees C in the temperature range from 350 degrees C to 450 degrees C. Quantitative particle analysis of the sheets after the whole annealing cycle indicate that the alloy deformed 96% shows the highest density of particles in the size range from 50 to 140 nm.
In addition, many spherical particles up to 15 nm were observed by transmission electron microscopy, some of them were identified by electron diffraction as Al3Zr phase with L12 crystal structure. (C) 2015 Elsevier Ltd. All rights resented.