THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe

Solid iron can be observed at environmental conditions and also as metallic component of quasicrystalline alloys. Its behavior in aqueous solution is analyzed from some particular thermochemical relationships. The model utilizes free Gibbs energy to obtain pH and ñå parameters which are related to i...

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Autores principales:	NASCIMENTO,LUCIANO, GOSTINHO,LOURDES CRISTINA L, CAVALCANTI,BERNARDETE F
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2013
Materias:	Iron thermochemical model Standard free energy Solid iron species
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072013000100023
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spelling	oai:scielo:S0717-970720130001000232014-09-09THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFeNASCIMENTO,LUCIANOGOSTINHO,LOURDES CRISTINA LCAVALCANTI,BERNARDETE F Iron thermochemical model Standard free energy Solid iron species Solid iron can be observed at environmental conditions and also as metallic component of quasicrystalline alloys. Its behavior in aqueous solution is analyzed from some particular thermochemical relationships. The model utilizes free Gibbs energy to obtain pH and ñå parameters which are related to iron redox reactions. The solid iron system, defined as Fe : Fe2+ - Fe3+ - Fe2O3 (hematite) - Fe3O4 (magnetite), was modelled by considering a low molar concentration and environmental temperature. In order to obtain pε values, equations relating Gibbs standard free energy and equilibrium constants were applied. A stability diagram such as pe x pH was chosen to depict these thermochemical relationships. Thus, straight line dpε/dpH slopes were obtained for each process step of the solid iron system. In systems relating solid iron to iron species Fe2+ and Fe3+ the slopes are equal to zero; i.e. horizontal line shows the iron species dominance in some specific pH (hydronium ions) range. The negative values obtained show the pH dependence of the iron species investigated. In natural water environment, it is possible to distinguish hematite formation from magnetite formation. However in quasicrystalline AlCuFe alloys the last iron species formed is hematite which ion pairs to copper. Due to the strong hydronium ions (pH) dependence, it is necessary to measure it both in environmental conditions and quasicrystalline phase's formation. Considering that the temperature adopted was 25°C, the results are valid only for this temperature.info:eu-repo/semantics/openAccessSociedad Chilena de QuímicaJournal of the Chilean Chemical Society v.58 n.1 20132013-03-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072013000100023en10.4067/S0717-97072013000100023
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Iron thermochemical model Standard free energy Solid iron species
spellingShingle	Iron thermochemical model Standard free energy Solid iron species NASCIMENTO,LUCIANO GOSTINHO,LOURDES CRISTINA L CAVALCANTI,BERNARDETE F THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe
description	Solid iron can be observed at environmental conditions and also as metallic component of quasicrystalline alloys. Its behavior in aqueous solution is analyzed from some particular thermochemical relationships. The model utilizes free Gibbs energy to obtain pH and ñå parameters which are related to iron redox reactions. The solid iron system, defined as Fe : Fe2+ - Fe3+ - Fe2O3 (hematite) - Fe3O4 (magnetite), was modelled by considering a low molar concentration and environmental temperature. In order to obtain pε values, equations relating Gibbs standard free energy and equilibrium constants were applied. A stability diagram such as pe x pH was chosen to depict these thermochemical relationships. Thus, straight line dpε/dpH slopes were obtained for each process step of the solid iron system. In systems relating solid iron to iron species Fe2+ and Fe3+ the slopes are equal to zero; i.e. horizontal line shows the iron species dominance in some specific pH (hydronium ions) range. The negative values obtained show the pH dependence of the iron species investigated. In natural water environment, it is possible to distinguish hematite formation from magnetite formation. However in quasicrystalline AlCuFe alloys the last iron species formed is hematite which ion pairs to copper. Due to the strong hydronium ions (pH) dependence, it is necessary to measure it both in environmental conditions and quasicrystalline phase's formation. Considering that the temperature adopted was 25°C, the results are valid only for this temperature.
author	NASCIMENTO,LUCIANO GOSTINHO,LOURDES CRISTINA L CAVALCANTI,BERNARDETE F
author_facet	NASCIMENTO,LUCIANO GOSTINHO,LOURDES CRISTINA L CAVALCANTI,BERNARDETE F
author_sort	NASCIMENTO,LUCIANO
title	THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe
title_short	THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe
title_full	THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe
title_fullStr	THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe
title_full_unstemmed	THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe
title_sort	thermodynamic study of iron in alloys of quasicrystalline alcufe
publisher	Sociedad Chilena de Química
publishDate	2013
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072013000100023
work_keys_str_mv	AT nascimentoluciano thermodynamicstudyofironinalloysofquasicrystallinealcufe AT gostinholourdescristinal thermodynamicstudyofironinalloysofquasicrystallinealcufe AT cavalcantibernardetef thermodynamicstudyofironinalloysofquasicrystallinealcufe
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THERMODYNAMIC STUDY OF IRON IN ALLOYS OF QUASICRYSTALLINE AlCuFe

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