Microstructure of two-phase Al-1.7 at% Cu alloy deformed by equal-channel angular pressing

The microstructural changes of an aged Al-1.7 at% Cu alloy associated with severe plastic deformation have been studied by transmission electron micro scopy (TEM) and energy-filtered transmission electron microscopy (EF-TEM). m theta' precipitates are almost completely dissolved after eight passes of equal-channel angular (ECA) pressing, and nearly single-phase alpha with a fine grain size of approximately 500 nm is obtained. When a severely defor med sample is aged for 24 h at 100 degreesC, precipitation of equiaxed thet a phase is observed along the grain boundaries, whereas only Guinier-Presto n (GP) zones are formed in the undeformed sample. The dissolution and preci pitation processes in severely deformed Al-1.7 at% Cu alloy have been exami ned by TEM and energy-filter mapping. (C) 2001 Acta Materialia Inc. Publish ed by Elsevier Science Ltd. All rights reserved.