11729

10761

كارشناسي ارشد

ريخته گري

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1395

سيزده،[62]ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

حسين ادريس، علي دوست محمدي

محمدرضا طرقي نژاد، احمد رضاييان

1395/08/16

كتابنامه

مهندسي مواد

ID10761

61Investigation of mechanical and corrosion behavior of NiTiMo shapememory alloy fabricated by casting Seyyed Mohammad Mohsen Abdar Esfahani M Abdar@ma iut ac ir July 31 2016 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr H Edris Assoc Prof E Mail h edris@cc iut ac irAbstractExamination of mechanical as well as corrosion properties in Flouride solution of NiTiMoshape memory alloy was the aim of present study The NiTiMo was prepared with vacuumarc melting in cupreous crucible To insure homogeneity of alloy the alloy was remeltedfor six times The as cast alloy was annealed at 950 C for 1 hour followed by quenching inliquid nitrogen The microstructure was studied by X ray diffraction analysis optical andelectron microscopes Tensile and three point bending tests were employed to examinatetensile and shape memory properties The corrosion resistance of NiTiMo alloy wasinvestigated by Electrochemical Impedance Spectroscopy as well as Tafel polarization test The recoverable strain of NiTiMo alloy after anealling and quenching was 7 79 percentachieved The NiTiMo alloy was immersed in flouride solution for 8 16 and 72 hourfollowed by tensile testing The results showed that with the increase of immersing time beginning stress of detwinning increased and the fracture stress decreased The decrease oftensile strength is due to absorption of Hydrogen and embrittlement effect of hydrogen Fracture surface of the non immersed specimens was incorporated cleavage facets Fracture of large intermetallic precipitates within the microstructure was found to be thesource of the cleave cracks For immersed specimens both of internal and surface openedcracks was observed Surface opened cracks was initiated from interaction of the surface ofalloy and Flouride solution and extended to internal regions With the increase ofimmersing time the number of surface cracks as well as as the length of surface cracks perunit length of the specimens was increased It was observed that the region behind thecontact surface of the alloy and fluoride solution up to a distinct depth showed completelybrittle fracture behavior It could be due to the high concentration of hydrogen atoms Theresults showed that presence of Mo in NiTi alloy caused form the passive film on NiTiMoalloy and increase of corrosion resistance Keywords shape memory alloys Ni Ti Mo corrosion Hydrogen embrittlement

حسين ادريس، علي دوست محمدي

محمدرضا طرقي نژاد، احمد رضاييان