7194

6700

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1391

پانزده، 123ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

فتح ا... كريم زاده، محمد حسين عنايتي

10/8/91

محمدعلي گلعذار، مهدي صالحي

1396/09/20

كتابنامه

مواد

مهندسي مواد

ID6700

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

125 Fabrication of Al Al2O3 Nanocomposite with Mechanical Milling and Hot Pressing and Evaluation of their Dissimilar Joint Prepared by Friction Welding Vahab Rastar v rastar@ma iut ac ir Date of submission 4 22 2012 Department of Material Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor F Karimzadeh karimzadeh f@cc iut ac ir M H Enayati ena78@cc iut ac ir Abstract Aluminum matrix composites reinforced by ceramic particles are one of the promising materials for engineering applications Joining of aluminum matrix composite components can be done by various methods based on fusion welding and solid state welding Friction welding FW as a solid state welding process has some advantages over fusion welding such as smaller heat input lower residual torsion and thermal stresses and lack of undesirable microstructure from solidification In this research aluminum matrix composite powders containing 5 10 and 15 wt of Al2O3 nano particles were produced by mechanical milling Then bulk specimens 42 12 12 mm were produced by hot pressing of mechanically milled powder Finally the bulk samples were welded to 2014 Al alloy with constant welding parameters The results showed that after 5 hours of ball milling an Al Al2O3 nanocomposite structure with an Al grain size of 75 nm was achieved This structure remained unchanged after hot pressing The increasing Al2O3 content increased the hardness value of bulk samples but reduced their density and bending strength It was revealed that the fracture of bulk nanocomposites occurred by interparticle brittle fracture mechanism Microstructural observations of dissimilar welds of Al Al2O3 nanocomposites and 2014 Al alloy showed a fully plasticized region Zpl in joint boundary and a partly deformed region Zpd in the region far from joint line in both side of the weld Plastic deformation mechanical mixing and high temperature near weld line led to a uniform structure Zpl region for nanocomposite side with no traces of interparticle boundaries and lamellar structure resulting from milling process Increasing the amount of Al2O3 particles in nanocomposite increased the heat produced during welding processes The amount of axial up set shortening and the width of Zpl region in case of sample with 5wt Al2O3 was maximum owing to high plastic deformation In all cases hardness of weld zone in nanocomposite and 2014 Al alloy side were reduced in comparison with base metal but it should be note that hardness value of joint boundary in 2014 Al alloy side was not the minimum value While the bending strength of nanocomposite significantly reduced by increasing the reinforcement content fracture in all cases were found to occur by brittle mechanism with cleavage morphology and that the crack was developed in the nanocomposite side The results of friction welding of nanocomposite containing 5wt Al2O3 demonstrated that the axial up set and the width of Zpl region were increased by increasing the frictional forging pressure and also increasing the rotation speed Also TEM study of Zpl region in these system showed the uniform distribution of Al2O3 nano particles but Al nanocrystalline structure did not remain in nano sized scale in these zone probably because of formation of recrystallized grains Keywords Nanocomposite Friction Welding Al2O3 Nano Particles 2014 Al Alloy Mechanical Milling Hot Pressing Dissimilar Welding

فتح ا... كريم زاده، محمد حسين عنايتي

محمدعلي گلعذار، مهدي صالحي