Papers by Keyword: Equal Channel Angular

Abstract: The progress in bulk ultrafine and nanostructured materials through consolidation of particles by severe plastic deformation (SPD) is reviewed. The focus is on the processes of high pressure torsion (HPT) and equal channel angular pressing (ECAP) with or without the application of a back pressure. Various materials consolidated are described in terms of their densities, microstructures and mechanical properties. The important processing parameters and their effects on the resulting materials are discussed. It is shown that SPD consolidation of particles is an effective way of producing bulk nanostructured materials although much work is needed to understand the consolidation behaviour and to design the optimum compositions and microstructures.

Abstract: An innovative process for synthesising bulk materials using particles has been developed. The process is termed back pressure equal channel angular consolidation (BP-ECAC). Aluminium based materials were successfully consolidated into bulk materials using particles from nano to micro scales. BP-ECAC allowed the particles to be used directly without pre-compacting and casing and the processing temperatures to be significantly lower than those used in conventional sintering. Fully dense bulk samples were obtained instantaneously as the particles were forced to pass the shearing zone under pressure. Nanostructured materials were obtained from the nanometre-sized Al particles. Significant strengthening of the consolidated materials were observed. The new process is promising in producing porosity free, large volume materials with special compositions and structures.

Abstract: Pure aluminium and titanium powders were successfully synthesised into bulk materials using equal channel angular (ECA) consolidation. Powders were used directly without the need to cold-compact them into green bodies. The processing temperatures were significantly lower than the usual sintering temperatures for aluminium and titanium. Fully dense bulk samples were achieved after one pass of ECA deformation through a 90 degree die. Mechanical properties of the as-ECA processed materials were comparable to those of wrought aluminium and titanium through ingot metallurgy. Multiple passes of ECA deformation resulted in refined microstructure and improved mechanical properties. The new process has many advantages over conventional powder sintering and is capable of producing bulk nanomaterials of high integrity.