6561

6126

كارشناسي ارشد

مهندسي مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مواد

1390

دوازده، 68ص.: مصور، جدول، عكس، نمودار

ص.ع. به فارسي و انگليسي

مرتضي شمعانيان،فخرالدين اشرفي زاده

محمد حسين عنايتي

15/1/90

مسعود پنجه پور، علي شفيعي

1396/10/10

كتابنامه

مواد

مهندسي مواد

ID6126

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Production and Characterization of CoTi TiC Nanocomposite by Mechanical Alloying Amirhossein Molladavoudi a molladavoudi@ma iut ac ir July 23 2011 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor s Dr Morteza Shamanian Assoc Prof E Mail shamanian@cc iut ac irSupervisor s Dr Fakhreddin Ashrafizadeh Prof E Mail ashrafif@cc iut ac irAbstractIntermetallic compounds have been the focus of significant research and development efforts during the last15 years The promise of very strong tough structural materials at elevated temperatures has tantalizedresearchers for several decades The technological attraction comes mainly from new aerospace needs forhigh temperature structural materials with properties that cannot be met by ceramics or by conventionalsuperalloys Intermetallic CoTi has received a great deal of attention as candidate materials for high temperature applications because of its low density high specific strength good oxidation and corrosionresistance at elevated temperatures Several techniques such as self propagating high temperature synthesis SHS reactive hot press andmechanical alloying MA have also been developed to produce a wide array of intermetallic matrixomposites Among these methods MA technique is well known for synthesis of compounds andnanocomposites using the mechanochemical reactions MA is a technique to roduce powders with uniquemicrostructures such as nanoscale structures and morphous phases Its attraction is that it has a near net shape product which can greatly reduce the shaping process Therefore Mechanical alloying method wasused in this research to study the formation and properties of CoTi nanocomposite reinforced by TiCparticles Ball milling process was performed in two stages first producing the nano structured CoTiintermetallic and second formation of TiC reinforcement in CoTi matrix followed by in situ production ofCoTi TiC nanocomposite Mechanical alloying of pure cobalt titanium and carbon powders withstoichiometric ratio and Ball to Powder Weight Ratio of 10 1 and 5 1 was carried out using a high energyball mill with speed of 300 rpm in various time intervals Heat treatment process was carried out in vacuumfurnace at 900 C for 30 and 60 min Transition and scanning electron microscopes and X ray diffractiontechnique were employed to examine the microstructural evolution In addition crystallite size and latticedistortion changes in the powder mixtures were investigated using the sigma plot software and Williamson Hall method at different stages The results showed that an increase in Ball to Powder Weight Ratio from 5 1to 10 1 lead to a decrease in production time of CoTi from 20 to 8 hours a decrease in grain size and aconsiderable increase in internal strain and hardness in the final specimens The CoTi phase obtained had aparticle size of about 10 m crystallite size of 14 nm and lattice distortion of 0 5 The CoTi TiCnanocomposite represented a particle size of about 15 m crystallite size of 15 nm and lattice distortion of1 5 In all specimens increase in ball milling time was associated with an increase in hardness and latticedistortion and a decrease in crystallite size of powder mixtures The hardness of CoTi was varied from 470 to390 HV whereas the hardness of CoTi TiC composite was in the range from 900 to 760 HV Keywords TiCo TiCo TiC Intermetallic Mechanical alloying Nanocomposite Milling Nanostructure

مرتضي شمعانيان،فخرالدين اشرفي زاده

محمد حسين عنايتي

مسعود پنجه پور، علي شفيعي