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## Thermal stability analysis of titanium specified hydrostatic extrusion

### Sylwia Obarska

#### Abstract

The aim of this study was investigation the thermal stability of the Grade 2 nanocrystalline titanium and the high-purity titanium after hydrostatic extrusion as well. Modulated Differential Scanning Calorimetry (MDSC) was used to study transformations which take place in material during heating. In addition, annealing in the temperature of 250 oC was applied to compare results with the previous ones. Microhardness measurements HV0,2 allowed to reveal mechanical properties of the annealed materials. It was observed that calorimetric curves of Grade 2 titanium and high-purity titanium formed during the MDSC measurements differ from each other. Analysis of the Grade 2 titanium plot revealed an additional pick in the temperature area of 250 oC which may be caused by the diffusion processes of the impurity atoms. It is assumed that thermal stability of a material correlates strictly with its mechanical properties, specifically drop of mechanical properties more than 10%, compared to the state after SPD, entails loss of thermal stability. Taking that into consideration, intensive grain growth of high-purity and Grade 2 titanium occurs at 340oC and 400oC respectively what is proved by rapid increase of a heat flow on a calorimetric curve. In addition, it was found that conventional annealing in the temperature of 250 oC affected the samples differently. Half an hour of annealing was sufficient to cause the hardness drop of the high-purity titanium while in Grade 2 titanium increase of the hardness value was observed. Conducting the research into thermal stability of titanium allowed to determine temperature of thermal stability loss of nanocrystalline titanium. Additional low-temperature annealing processes in the temperature of 250 oC allowed to verify the literature data and confirmed the hardness increase of 20-30HV of the nanocrystalline Ti Grade 2 specimens. That effect wasn’t observed in the high-purity titanium specimens whereas the increase of annealing time caused the hardness drop.
Record ID
WUT707ff2369e5e4377bf077b6f464d85d7
Diploma type
Master of Science
Author
Sylwia Obarska (FMSE/DMD) Sylwia Obarska,, Division of Materials Design (FMSE/DMD)Faculty of Materials Science and Engineering (FMSE)
Title in Polish
Analiza stabilności cieplnej tytanu poddanego wyciskaniu hydrostatycznemu
Supervisor
Halina Garbacz (FMSE/DMD) Halina Garbacz,, Division of Materials Design (FMSE/DMD)Faculty of Materials Science and Engineering (FMSE)
Certifying unit
Faculty of Materials Science and Engineering (FMSE)
Affiliation unit
Division of Materials Design (FMSE/DMD)
Study subject / specialization
, Nanomateriały i Nanotechnologie
Language
(pl) Polish
Status
Finished
Defense Date
12-11-2012
Issue date (year)
2012
Internal identifier
IM-D.001663
Reviewers
Jarosław Mizera (FMSE/DMD) Jarosław Mizera,, Division of Materials Design (FMSE/DMD)Faculty of Materials Science and Engineering (FMSE) Katarzyna Konopka (FMSE/DSMP) Katarzyna Konopka,, Division of Ceramic Materials and Polymers (FMSE/DSMP)Faculty of Materials Science and Engineering (FMSE)
Abstract in Polish
urn:pw-repo:WUT707ff2369e5e4377bf077b6f464d85d7