9536

709 دكتري

دكتري

مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1393

دوازده،189ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

مرتضي شمعانيان اصفهاني، محمود منير واقفي

Jerzi A. Szpunar

18/11/93

فخرالدين اشرفي زاده، ابراهيم حشمت دهكردي، حسين احمدوند

مهندسي مواد

ID709 دكتري

ssessment of high energy beams micro welds in ultra thin FeCo V foilsA to optimize magnetic and mechanical properties Hossein Mostaan H Mostaan@ma iut ac ir December 31 2014 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranSupervisors Morteza Shamanian shamanian@cc iut ac ir Sayed Mahmoud Monir Vaghefi vagh mah@cc iut ac irAdvisor Jerzy A SzpunarAbstractIn this research microstructural evolutions and grain boundary character distributionduring high energy beam welding processes of ultra thin FeCo V foils were studied Also mechanical and magnetic properties evolutions during high energy beam welding werestudied using tensile test and vibrating sample magnetometry VSM respectively It wasfound that the fractions of low angle boundaries increase in the fusion zones of bothelect on and lase beam welded foils he esults showed that the f actions of low boundaries especially twin boundary 3 in the fusion zones of the welded foils arehigher than those of base metal Since the strain rates produced during high energy beamwelding is very high duo to the extremely high cooling rate grain deformation by slipmechanism is limited and therefore deformation by grain twinning is dominant VSManalysis showed that the welded foils experience a significant decrease in their magneticproperties i e remanence coercive force and energy product The results demonstratedthat all of the welded specimens fractured in the fusion zones Keywords FeCo V alloys Ultra thin magnetic foils micro welding Mechanicalproperties Magnetic properties 1 IntroductionFeCo alloys in the composition range 35 50 cobalt have the highest known roomtemperature saturation magnetization 1 These alloys are characterized by low coercivity high permeability high tensile strength high Curie temperature TC and are oftechnological interest for power generation and power conversion applications 2 Thebinary alloys however are rarely used commercially due to their extreme brittleness It hasbeen shown that an increase in ductility is given by a small addition of vanadium 3 Thisfact along with the high temperature stability of magnetic characteristics makes the FeCo V alloys virtually suitable for producing active parts of rotors of synchronous hysteresismotors SHMs and magnetic bearing 4 During heating of these alloys various phasetransformations occur which severely affect the magnetic and mechanical properties of thealloy These transformations are order disorder allotropic transformation and finallyp ecipitation of vanadium ich 2 phase Co3V 5 To function as a rotor for high speedengines and obtain the maximum efficiency permanent magnets should have high

مرتضي شمعانيان اصفهاني، محمود منير واقفي

Jerzi A. Szpunar

فخرالدين اشرفي زاده، ابراهيم حشمت دهكردي، حسين احمدوند