HIGH SPEED HIGH PRESSURE TORSION EFFECTS ON A DIFFICULT DEFORMABLE SHAPE MEMORY ALLOY

Gheorghe Gurau, Carmela Gurau, Leandru-Gheorghe Bujoreanu, Francisco Manuel Braz Fernandes

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

High pressure torsion (HPT) is a severe plastic deformation process, able to reduce grain size, down to nanostructure or amorphous level, in bulk materials. In the experiments a modified high speed HPT (HS-HPT) technique was used. It was ideally suited for products about 50 mm in diameter, contributing to a meaningful increase of mechanical properties. This type of severe plastic deformation generates large plastic deformation in entire volume of sample under the effect of high pressure cumulated with high rotation. On the strength of friction and pressure the sample was heated, took place grain fragmentation up to (ultra) fine grains, nanocrystalline or amorphous areas, without recrystallization. The effect of severe plastic deformation via High Pressure Torsion (HPT) on microstructure of the Cu-Al-Ni shape memory alloys was investigated by optical (OM). The reversible martensitic transformation temperatures were investigated using differential scanning calorimetry (DSC) as effect of microstructure refinement appropriate to different deformation degrees. The hardness tests demonstrate that creating ultrafine grain with high strength can produce reliable lightweight metallic parts. The presence of monoclinic and orthorhombic martensite, together with nanocrystalline areas were confirmed by X-ray diffraction (XRD).

Original languageEnglish
Title of host publicationGEOCONFERENCE ON NANO, BIO AND GREEN - TECHNOLOGIES FOR A SUSTAINABLE FUTURE, VOL I (SGEM 2014)
PublisherSTEF92 TECHNOLOGY LTD
Pages93-99
Number of pages7
Publication statusPublished - 2014
Event14th International Multidisciplinary Scientific Geoconference (SGEM) - Albena, Bulgaria
Duration: 17 Jun 201426 Jun 2014

Publication series

NameInternational Multidisciplinary Scientific GeoConference-SGEM
PublisherSTEF92 TECHNOLOGY LTD
ISSN (Print)1314-2704

Conference

Conference14th International Multidisciplinary Scientific Geoconference (SGEM)
CountryBulgaria
CityAlbena
Period17/06/1426/06/14

Keywords

  • Severe Plastic Deformation
  • High Pressure Torsion
  • Shape Memory Alloys
  • Structure
  • Transformation Temperature
  • Martensite
  • Cu-Al-Ni shape memory alloy
  • grain size
  • SEVERE PLASTIC-DEFORMATION

Cite this

Gurau, G., Gurau, C., Bujoreanu, L-G., & Braz Fernandes, F. M. (2014). HIGH SPEED HIGH PRESSURE TORSION EFFECTS ON A DIFFICULT DEFORMABLE SHAPE MEMORY ALLOY. In GEOCONFERENCE ON NANO, BIO AND GREEN - TECHNOLOGIES FOR A SUSTAINABLE FUTURE, VOL I (SGEM 2014) (pp. 93-99). (International Multidisciplinary Scientific GeoConference-SGEM). STEF92 TECHNOLOGY LTD.