Production of fine grained structures in aluminum powders by equal channel angular densification/pressing method and deformation behaviour of this material

In this study, aluminum powders produced by powder metallurgy are consolidated to high density with ultra-fine grained structure at very low temperatures by Equal Channel Angular Densification/Pressing (ECAD/ECAP) processes in a furnace with hidrolic press. Also deformation capabilities of this material have been investigated.The ECAD/ECAP processes have been carried out using route C at various temparatures (50ºC, 100ºC, 200ºC and room temparature) and pass number as well as press punch speed of 1mm.s-1 in a special mould which has high toughness. The tensile test specimens were prepared from the bulk materials produced by ECAD/ECAP processes. Then, tensile tests were conducted at10-3 s-1 strain rate and room temperature. For comparison, aluminum powders were also consolidated in a mould without ECAD/ECAP process at the same temperatures (200ºC, 100ºC ve 50ºC) and then these specimens were also tested at the same ECAD/ECAP and deformation conditions. Eventually, obtained results were compared. The relationship between structure, process and properties are linked. For this, microstructural characterization (grain size measurement, grain shape, grain boundary angle misorientation) was conducted using transmission (TEM) and scanning electron microscopies (SEM).As a result, the ECAD/ECAP process was shown to provide an effective method for producing materials which have high mechanical properties (high density, ultra fine grained, high strength, high hardness) compared to the results of unECAD/ECAPed samples.Key Words :Equal Channel Angular Densification/Pressing (ECAD/ECAP), Powder Metallurgy, Aluminum Powders, Fine-Grained Structure, Microstructural Characterization