Hot Workability Behaviour of Cryomilled and Spark Plasma Sintered 2024 Al Alloy

摘要

In this work it has been investigated the hot deformation of a 2024 Al alloy obtained by spark plasma sintering of cryomilled powder. This behaviour was compared with the one of a sample produced with atomized powder. Different hot deformation responses were observed since their microstructures are different. In the milled sample grains are nanometric and ultrafine and contain some precipitates. A much higher concentration was observed in the atomized specimen, since this powder is a supersaturated solid solution and SPS causes the whole of the precipitation sequence, resulting in the extensive intragranular precipitation of incoherent particles. The different microstructures lead to a different hot compression behaviour. Milled alloy has a higher flow stress and shows a peculiar stress-strain curve characterized by a sharp peak of the flow stress followed by a rapid decrease. This work softening was correlated to the phenomenon of the dynamic precipitation occurring only in the milled specimen.