Thermal stability of twin-roll cast Al-Fe-Mn-Si sheets accumulative roll bonded at different temperatures

Accumulative roll bonding (ARB) allows production of large amounts of ultra-fine grained materials. Therefore, ARB is suitable for industrial applications. Refinement efficiency is improved when the input materials contain fine particles, such as in twin-roll cast (TRC) alloys. The effect of the ARB temperature on bond strength, microstructure, properties and thermal stability of a TRC Al-Fe-Mn-Si alloy was studied. After two cycles at 200 degrees C, grain sizes of 0.4-0.8 mu m are achieved along with areas of grain sizes of 0.08-0.3 mu m. The hardness increases significantly during first two ARB cycles and afterwards it increases less. Processing at higher temperatures produces a better bonding but smaller hardness increments. Partial recrystallization during heating above 250 degrees C results in a less effective grain refinement depending on the annealing temperature and on the number of cycles. The thermal stability of the samples processed at 250 degrees C is better as compared to higher temperatures and to conventional cold rolling. (C) 2006 Elsevier B.V. All rights reserved.