Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Thermodynamic investigation of Co-Cr alloys, III: Thermo-analytical measurements using DSC and DTA techniques
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
2006 (English)In: INTERNATIONAL JOURNAL OF MATERIALS RESEARCH, ISSN 1862-5282, Vol. 97, no 11, 1533-1538 p.Article in journal (Refereed) Published
Abstract [en]

Several Co-Cr alloys have been investigated by Differential Scanning Calorimetry (DSC) as well as by Differential Thermal Analysis (DTA) in the temperature range 2981823 K. The compositional range investigated was from 0 to 87 wt.% Cr with special attention given to alloys with low Cr contents, i.e. 0 to 10 wt.% Cr. From the DSC measurements molar heat capacity values, phase transformation temperatures, enthalpies of transformation and Curie transition temperatures were derived. From the DTA measurements, the melting temperatures and melting enthalpies were evaluated. The trends obtained were compared with the results for pure Co as well as the proposed phase diagram reported in literature.

Place, publisher, year, edition, pages
2006. Vol. 97, no 11, 1533-1538 p.
Keyword [en]
differential scanning calorimetry, differential thermal analysis, Co-Cr, experimental thermodynamics
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-6402ISI: 000242436700008Scopus ID: 2-s2.0-33751401404OAI: oai:DiVA.org:kth-6402DiVA: diva2:11101
Note
Uppdaterad från submitted till published: 20100930. QC 20100930Available from: 2005-09-14 Created: 2005-09-14 Last updated: 2010-09-30Bibliographically approved
In thesis
1. Thermodynamic Study of Co-Cr and C-Co-Cr Systems
Open this publication in new window or tab >>Thermodynamic Study of Co-Cr and C-Co-Cr Systems
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

An experimental investigation of the binary system Co-Cr and the ternary system C-Co-Cr has been carried out in the present thesis. The experimental strategy adopted for the binary system was to measure the thermodynamic activities of Cr, the molar heat capacity as function of time, the phase transformation temperatures with corresponding enthalpies, the Curie transition temperature as well as melting temperatures with corresponding enthalpies. In the ternary system the strategy was to determine the solubility of Co in the Cr7C3 phase as well as the C and Cr contents in the Co rich (fcc) binder phase. The experimental results were compared with atomistic simulations of the solubility of Co in the Cr7C3 phase.

Solid state galvanic cell measurements were conducted with both ZrO2-7.5 mol % CaO and CaF2 as the solid electrolyte. In view of possible errors in the measurements with ZrO2-7.5 mol % CaO, as a result of electronic contributions to the conduction of the solid electrolyte, new measurements were conducted with CaF2 as the solid electrolyte. The results indicated that the measured EMF values showed trends which were contrary to the thermodynamic behaviour expected from phase diagram considerations. It was concluded that further detailed experimentation was necessary in order to throw more light on the thermodynamic behaviour of the Co-Cr system.

Two different series of DSC measurements were conducted, i.e. one in an atmosphere of pure hydrogen and another in pure argon. In the first investigation, conducted in an atmosphere of pure hydrogen in the temperature interval 318-1660 K, evidence was obtained for the existence of a phase transformation around 900 K in the compositional range 20.7-67.1 wt.% Cr. No indications of such a phase transformation had earlier been seen. In the second investigation, conducted in an atmosphere of pure argon in the temperature interval 298-1823 K, special attention was given to alloys in the Co rich corner of the phase diagram, i.e. 0-10 wt.% Cr. This investigation verified earlier findings of a phase transformations around 900 K in the compositional range 20.7-67.4 wt.% Cr. The magnetic transition temperatures for alloys low in Cr content were also obtained. With the use of the DTA technique the melting temperatures with corresponding enthalpy values for alloys in the compositional range 0.9-7.7 wt.% Cr were obtained.

The three-phase triangle fcc+Cr7C3+graphite was investigated at 1373 K, 1423 K and 1473 K. The obtained results showed that the solubility of cobalt in the Cr7C3 phase was significantly higher than previously predicted by thermodynamic calculations.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 110 p.
Keyword
Cobalt, chromium, carbon, experimental thermodynamics, , solid state galvanic cell technique, differential scanning examination
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-418 (URN)91-7178-125-0 (ISBN)
Public defence
2005-09-23, K2, teknikringen28, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100930Available from: 2005-09-14 Created: 2005-09-14 Last updated: 2010-09-30Bibliographically approved

Open Access in DiVA

No full text

Scopus

Search in DiVA

By author/editor
Sterneland, Therese
By organisation
Materials Science and Engineering
Metallurgy and Metallic Materials

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 65 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf