بررسي ساختار و خواص مكانيكي كامپوزيت لايه اي آلومينيوم-تيتانيوم توليد شده توسط فرايند نورد تجمعي

چكيده انگليسي :

Evaluation of Structure and Mechanical Properties of Multi LayeredAl Ti Composite Produced by Accumulative Roll Bonding ARB Process Arian Eghbali a eghbalimiandoab@ma iut ac ir Department of Materials Engineering Isfahan University of Technology 84156 83111 Isfahan IranDegree M Sc Language FarsiDr Mohammad Reza Toroghinejad Assoc Prof Supervisor E mail toroghi@cc iut ac irDr Hossein Edris Assoc Prof Supervisor E mail h edris@cc iut ac irDr Fakhreddin Ashrafizadeh Prof Advisor E mail Ashrafif@cc iut ac irAbstractTechniques of severe plastic deformation have been of continual interest in the production of novelmetallic microstructures Among these techniques accumulative roll bonding has been extensivelyused to produce multi layered composites ARB process can be used as an innovative andappropriate way of multi layer composite production for the sake of its simplicity and cheaperprimary commodity Multi layered Al Ti composites were produced by accumulative roll bonding ARB process using Al 1100 and commercial Ti sheets Sheets were cut into 5cm 10 cm in sizeand degreased with acetone and wire brushed Al sheets 500 m thick and Ti sheets 600 m thichwere used in this study After degreasing with acetone and scratch brushing by circular steel brush the brushed sheets were stacked in the manner of two aluminum layers clad alternatively to onetitanium layer Roll bonding was conducted under the condition that the reduction in thickness percycle was 50 This 1 8 mm multilayer sample was rolled down to 0 8 mm thick The roll bondedsheet was cut into two sheets of initial dimensions The sample was scratch brushed stacked andthen rolled again This procedure was repeated for up to eight cycles In this process it wasobserved that Ti layers necked and fractured as accumulative roll bonding passes increased multilayered Al Ti composite with homogeneously distributed fragmented Ti layers in aluminummatrix was produced After eight ARB passes Structure and mechanical properties of these multi layer composites were evaluated at different passes of ARB process During ARB it was observedthat the strength and micro hardness of produced composites increased as the strain increased withthe number of ARB passes The maximum tensile strength reached 360 MPa at the eighth cycle Microhardness of Al and Ti layers experienced a sharp rise after eight cycles of ARB from 28VHN and 187 VHN to 71 VHN and 315 VHN Fracture surface of the samples after the tensiletest were examined using scanning electron microscopy SEM Observation revealed evidence ofa mixture of mechanisms cleavage and ductile failure The crystallite size of Al and Ti werecalculated using MAUD software that based on Riet Veld method transmission electronmicroscopy micrograph showed that the Al grain size reached to 300 nanometer after 8 cycles ofARB It was observed that the layer thickness of diffused atoms between Al and Ti were increasedby increasing the number of ARB cycles X ray diffraction patterns of the rolled samples show thatthere is no new crystalline phase Heat treatment at different temperatures of 550 C 600 C and700 C was applied to the as rolled laminates XRD and EDS analysis were used to define the newphases which have been produced in the heat treated samples This inermetallic was Al3Ti Effectof applied strain on the atomic diffusion was evaluated using x ray diffraction pattern of thecomposite samples which have been prodused after 4 6 and 8 ARB cycles and heat treated for 10minutes in 600 C The results show that diffusion rate of aoms and nucleation rate of Al3Ti wereincreased with increasing the applied strain Keywords Severe plastic deformation Accumulative roll bonding Multi layered Al Ticomposites Mechanical properties intermetallic

اقبالي مياندوآب، آرين

بررسي ساختار و خواص مكانيكي كامپوزيت لايه اي آلومينيوم-تيتانيوم توليد شده توسط فرايند نورد تجمعي

تغيير شكل پلاستيكي شديد , تركيب بي فلزي