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Bulk  nanostructured  titanium  fabricated  by  hydrostatic  extrusion

Krzysztof Topolski 1Halina Garbacz 1Waclaw Pachla 2Krzysztof J. Kurzydlowski 1

1. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
2. Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland


This  paper  is  concerned  with  Hydrostatic  Extrusion  (HE)  as  a  one  of  Severe  Plastic  Deformation  (SPD)  methods. The  material  investigated  was  pure  titanium  grade  2. Titanium  in  the  form  of  rod  was  subjected  to  multi-stage  extrusion  with  the  aim  to  grain  refine  and  improve  the  mechanical  properties. During  subsequent  operations  of  extrusion  the  rod  diameter  was  gradually  reduced. HE  is  a  technique,  which  permits  to  accumulate  the  strain  necessary  for  grain  refinement  and  obtain  the  nanostructure. The  important  and  basic  problem  concerned  with  nanometals  after  SPD  is  their  relative  small  volume. HE  emerged  recently  as  an  effective  method  of  the  production  of  bulk  nanostructured  metals. 

The  aim  of  this  study  was  to  optimize  the  HE  process  in  order  to  increase  the  nanostructured  titanium  rods  diameter. The  one  of  the  elementary  condition  of  the  nanostructure  receiving  is  to  accumulate  the  strain  above  three  (ε > 3). As  our  studies  show,  it  is  possible  to  obtain  nanostructured  Ti  rods  with  diameter  above  3mm  and   exceeded  5mm  also. The homogeneity  of  the  microstructure  and  the  grain  size  were examined  on  transverse  and  longitudinal  cross-sections  of  the  rods. The  average  grain size  on  the  transverse  cross-sections  appeared  to  be  below  100nm. The  grains observed  on  the  longitudinal  cross-sections  were  elongated  and  their  average  grain  size  exceeded  100nm. According  with  changes  of  structure  the  significant  improvement  of  mechanical  properties  was  observed. The  tensile  strength  was  more  than  1000MPa  and  hardness  increased  over  50%.


This work was carried out within a NANOMET Project financed under the European Funds for Regional Development (Contract No. POIG.01.03.01-00-015/08).


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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Krzysztof Topolski
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-26 18:08
Revised:   2009-08-26 11:12