ساخت و مشخصه يابي نانو كامپوزيت NiFe﴿3Al-Al2O3 ﴾ به روش آلياژ سازي مكانيكي و بررسي مكانيزم تشكيل آن

چكيده انگليسي :

Characterization and Formation Mechanism of Ni Fe 3Al Al2O3 Nanocomposite by Mechanical Alloying Zahra Adabavazeh Email address z adabavazeh@yahoo com Date of Submission April 9 2011 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisior s Name and Email address Fattollah Karimzadeh karimzadeh f@cc iut ac ir Mohammad Hossein Enayati ena78@cc iut ac irAbstractAccording researches the nickel aluminides exhibits advantageous properties including high meltingtemperature high tensile strength and yield point low density high hardness good thermal stability and highcreep resistance good corrosion and oxidation resistance at elevated temperatures These materials areparticularly ideal as high temperature structural materials The major barriers for the use of them as structuralmaterials are their low toughness and ductility at ambient temperature Recently much attention has beengiven to the investigation of ternary systems and ternary nanocomposites by mechanical alloying It leads tothe improvement of low ductility and toughness at ambient temperature The aim of this research was tosynthesis and characterization Ni Fe 3Al Al2O3 nanocomposite by mechanical alloying MA andevaluating its formation mechanism In first step Ni Fe 3Al intermetallic compound by mechanical alloying MA of Ni Fe and Al elemental powder mixtures with composition Ni50Fe25Al25 was successfullysynthesized The powders of Fe Al NiO or Fe2O3 Al Ni were mixed in the appropriate proportion to give Ni Fe 3Al Al2O3 nanocomposites The structural evolutions during mechanical alloying were studied byemploying X ray diffractometry XRD scanning electron microscopy SEM differential thermal analysis DTA transmission electron microscopy TEM and microhardness measurements The results showed that by mechanical alloying of elemental powder mixtures with composition Ni75Al25 and Ni50Fe25Al25 the Ni3Aland Ni Fe 3Al intermetallic compounds were synthesized with disordered L12 structures Heat treatment ofthese compounds at 700 for 0 5h and 800 900 and 1000 for 0 5h led to the formation of ordered Ni3Aland Ni Fe 3Al intermetallic compounds respectively Thermodynamic analysis of Ni Fe Al ternary systemindicated that the Ni Fe 3Al intermetallic compound is more stable compound These results are in goodagreement with experimental results The Ni Fe 3Al Al2O3 nanocomposite can be synthesized bymechanochemical reaction during ball milling of a stoichiometric starting powder mixture due to thereduction of Fe2O3 by Al and the reduction of NiO by Al Mechanical alloying of Ni Fe2O3 Al powdermixtures resulted in forming the Ni Fe 3Al 20 vol Al2O3 nanocomposite Thermal analysis wasconducted to test the thermal stability of the products Heat treatment of these compounds was conducted at900 for 1h led to the formation of ordered Ni Fe 3Al intermetallic compound and crystalline Al2O3 Thermodynamic parameter Tad is used to predict the modality of mechanochemical reactions during millingprocess The effects of different amount of Al2O3 on formation mechanism were investigated The Ni Fe 3Al 30 vol Al2O3 nanocomposite can be synthesized by reaction Fe Al NiO with a combustion mode Kinetic analysis showed that the synthesis of Ni Fe 3Al Al2O3 nanocomposites with using the model freemethods were respectively conducted with 101 and 309 kJ mol activation energies TEM results approve theformation of a nanostructured material Keywords Ni Fe 3Al Al2O3 nanocomposites Nanostructured materials Mechanical alloying Thermodynamicanalysis Reaction kinetic

ادب آوازه، زهرا

ساخت و مشخصه يابي نانو كامپوزيت NiFe﴿3Al-Al2O3 ﴾ به روش آلياژ سازي مكانيكي و بررسي مكانيزم تشكيل آن

مواد نانو ساختار , آناليز ترموديناميكي , سينتيك