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
Study of Mn activities in Mn-Ni-C alloys by EMF measurements
KTH, Superseded Departments, Materials Science and Engineering.
KTH, Superseded Departments, Materials Science and Engineering.
KTH, Superseded Departments, Materials Science and Engineering.
2003 (English)In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 11, no 11-12, 1229-1235 p.Article in journal (Refereed) Published
Abstract [en]

 The activities of manganese in Mn-Ni-C alloys have been studied by solid-state galvanic cell technique with CaF2 as the solid electrolyte. The measurements of electromotive force (EMF) have been carried out in the temperature range 920-1240 K. The main phase compositions of the alloys have been analyzed by X-ray diffraction (XRD). It was established that the substitution of Mn by Ni in the (MnNi)(23)C-6 carbide was limited, that the lattice parameter decreased slightly with increase in the Ni content and that a solid solution is formed between Mn and Ni. It was also found that the activity of manganese decreases with increase in the nickel content when the ratio of C/(Mn+C) is less than 8.3 wt.%, and that the negative effect of Ni on the activity of Mn in Mn-Ni-C ternary system decreases as the carbon content increases. However, when the ratio of C/(Mn+C) is equal to 8.3 wt.% or more, the activity of manganese is independent of the nickel content.

Place, publisher, year, edition, pages
2003. Vol. 11, no 11-12, 1229-1235 p.
Keyword [en]
A. Ternary alloy systems, B. Thermodynamic and thermochemical properties
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-5209DOI: 10.1016/S0966-9795(03)00163-8ISI: 000186687100020OAI: oai:DiVA.org:kth-5209DiVA: diva2:8026
Note
QC 20100930Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Thermodynamic investigations of transition metal systems containing coabon and nitrogen
Open this publication in new window or tab >>Thermodynamic investigations of transition metal systems containing coabon and nitrogen
2004 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

In view of the important applications of carbides and carbo-nitrides of transition metals in the heat-resistant and hard materials industries, the thermodynamic activities of Cr and Mn in the Cr-C, Fe-Cr-C, Mn-Ni-C and Mn-Ni-C-N systems have been studied in the present work by the use of the galvanic cell technique. CaF2single crystals were used as the solid electrolyte. The phase relationships in selected regions of the systems in question were investigated by the use of the equilibration technique. The phase compositions and microstructures of the alloys were analysed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).

In the Cr-C system, the Gibbs energy of formation of Cr3C2 were obtained from ElectroMotive Force (EMF) measurements conducted in the temperature range 950-1150 K. The values of the enthalpy of formation of Cr3C2 were evaluated by the third-law method. The ground-state energy of the hypothetic end-member compound CrC3, in the bcc structure at 0 K, was calculated by use of the Ab-initio method. Based on the obtained results the Cr-C system was reassessed by use of the CALPHAD approach.

In the Fe-Cr-C system, 16 different alloys were quenched at 1223 K and their equilibrium phases identified by XRD. The experimental results show that the substitution of Cr by Fe in the (Cr,Fe)7C3 carbide changes the lattice parameters of the phase. A slight decrease of the lattice parameters with an increase in the Fe content was established. The lattice parameters of the γ-phase in the Fe-Cr solid solution did also show a decrease with an increase of the Fe content. The activities of chromium in Fe-Cr-C alloys were investigated in the temperature range 940-1155 K. The activity of chromium decreases with an increase in the Fe content when the ratio of C/(Cr+C) was constant. It was also established that the activity of chromium decreases with an increase of the carbon content when the iron content was constant. The experimental results obtained were compared with the data calculated by use of the Thermo-Calc software.

In the Mn-Ni-C system the phase relationships were investigated at 1073 K as well as at 1223 K. The experimental results obtained showed that the site fraction of Ni in the metallic sublattice of the carbides M23C6, M7C3 and M5C2 (M=Mn and Ni) was quite low (approximately 2~3 percent). The activities of manganese in Mn-Ni-C alloys were investigated in the temperature range 940-1165 K. The three-phase region γ/M7C3/graphite was partly constructed at 1073 K.

In the Mn-Ni-C-N system, nitrogen was introduced into Mn-Ni-C alloys by equilibrating with N2 gas. It was established that the solubility of nitrogen in the investigated alloys was effected by the carbon content, and that a (Mn,Ni)4(N,C) compound was formed in the nitrided alloys. EMF measurements were performed on Mn-Ni-C-N alloys in the temperature interval 940-1127 K. The addition of nitrogen to Mn-Ni-C alloys was found to decrease the activity of manganese. The negative effect of nitrogen on the activity of manganese was found to decrease as the carbon content increased.

Keywords: Thermodynamic activity; Galvanic cell technique; Transition metal carbides; Transition metal nitrides; Phase equilibrium; Thermodynamics; Differential thermal analysis; Scanning electron microscopy; Transmission electron microscopy; Ab-initio calculations; CALPHAD approach;

Place, publisher, year, edition, pages
Materialvetenskap, 2004
Keyword
Materials science, thermodynamic activity, galvanic cell technique, transition metal carbides, transition metal nitrides, phase equilibrium, Materialvetenskap
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-24 (URN)91-7283-832-9 (ISBN)
Public defence
2004-10-08, Salongen, KTHB, Qsquars backe 31, Stockholm, 10:00
Opponent
Supervisors
Available from: 2004-10-08 Created: 2004-10-08 Last updated: 2012-03-21Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Teng, LidongAune, RagnhildSeetharaman, Seshadri
By organisation
Materials Science and Engineering
In the same journal
Intermetallics (Barking)
Materials Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 53 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