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Low-temperature compaction of Ti-6Al-4V powder using equal channel angular extrusion with back pressure
journal contribution
posted on 2008-08-25, 00:00 authored by Rimma Lapovok, D Tomus, B C MuddleEqual channel angular extrusion (ECAE), with simultaneous application of back pressure, has been applied to the consolidation of 10 mm diameter billets of pre-alloyed, hydride-dehydride Ti-6Al-4V powder at temperatures ≤400 °C. The upper limit to processing temperature was chosen to minimise the potential for contamination with gaseous constituents potentially harmful to properties of consolidated product. It has been demonstrated that the application of ECAE with imposed hydrostatic pressure permits consolidation to in excess of 96% relative density at temperatures in the range 100-400 °C, and in excess of 98% at 400 °C with applied back pressure ≥175 MPa. ECAE compaction at 20 °C (back pressure = 262 MPa) produced billet with 95.6% relative density, but minimal green strength. At an extrusion temperature of 400 °C, the relative density increased to 98.3%, for similar processing conditions, and the green strength increased to a maximum 750 MPa. The relative density of compacts produced at 400 °C increased from 96.8 to 98.6% with increase in applied back pressure from 20 to 480 MPa, while Vickers hardness increased from 360 to 412 HV. The key to the effective low-temperature compaction achieved is the severe shear deformation experienced during ECAE, combined with the superimposed hydrostatic pressure.
History
Journal
Materials science and engineering aVolume
490Issue
1-2Pagination
171 - 180Publisher
ElsevierLocation
Amsterdam, The NetherlandsPublisher DOI
ISSN
0921-5093Language
engPublication classification
C Journal article; C1.1 Refereed article in a scholarly journalCopyright notice
2008, Elsevier B.V.Usage metrics
Keywords
Ti-6Al-4V alloypowder compactionequal channel angular extrusionback pressureporesdensityScience & TechnologyTechnologyNanoscience & NanotechnologyMaterials Science, MultidisciplinaryMetallurgy & Metallurgical EngineeringScience & Technology - Other TopicsMaterials ScienceSEVERE PLASTIC-DEFORMATIONCONSOLIDATIONMechanical Engineering
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