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High strength Ti of substantial interstitial contents produced by back pressure equal channel angular consolidation of dehydrided particles

conference contribution
posted on 2008-06-01, 00:00 authored by Wei XuWei Xu, X Wu, D Sadedin, G Wellwood, K Xia
Back pressure equal channel angular (BP-ECA) processing was utilised to consolidate a dehydrided (DH) Ti powder of high interstitial content (1.15 wt.% O, 0.09 wt.% N) at 630°C into fully dense bulk ultrafine-grained (UFG) Ti. The consolidated samples showed an increase in the contents of oxygen (1.34 wt.%) and nitrogen (0.3 wt.%). The measured densities of 4.53 g/cm3 for the consolidated samples after 1 and 3 passes were very close to the theoretical value of pure Ti. TEM revealed the formation of a bimodal microstructure in the one-pass sample, comprising equiaxed grains of several micrometers in size with ultrafine grains of the order of 100 nm uniformly distributed at the triple grain junctions. Most grains had high-angle grain boundaries with some boundaries exhibiting non-equilibrium characteristics. Upon further BP-ECA processing to three passes, the micrometer-sized grains were refined down to the ultrafine level and copious nanoscale deformation twins were introduced by severe plastic strain into those ultrafine grains of the order of 100 nm. As a result of high interstitial contents and refined grains, the sample after processing for 3 passes exhibited remarkably enhanced true yield and ultimate strengths of 1510 and 2050 MPa, respectively. Significantly, a noticeable compressive ductility was simultaneously attained despite such a high interstitial content, thanks probably to the non-equilibrium grain boundaries, bimodal grain structure and the occurrence of deformation twinning.

History

Volume

584-586

Pagination

92-96

Location

Goslar, Germany

Start date

2008-08-18

End date

2008-08-22

ISSN

0255-5476

ISBN-13

9780878493753

Language

eng

Publication classification

E1.1 Full written paper - refereed

Editor/Contributor(s)

Estrin Y, Maier HJ

Title of proceedings

NanoSPD : Proceedings of the Fourth International Conference on Nanomaterials by Severe Plastic Deformation

Event

Nanomaterials by Severe Plastic Deformation. Conference (4th : 2008 : Goslar, Germany)

Publisher

Trans Tech Publications Ltd

Place of publication

Baech, Switzerland

Series

Nanomaterials by Severe Plastic Deformation Conference