Dissertation > Excellent graduate degree dissertation topics show

Magnetic Mechanism of the Fe-Nd-Al Amorphous Alloys

Author: HaoYanZuo
Tutor: BaiQin
School: Shanghai University
Course: Materials Science
Keywords: Fe-Nd-Al amorphous alloys hard magnetic property exchangecoupling interaction pinning effects
CLC: TG139.8
Type: Master's thesis
Year: 2013
Downloads: 3
Quote: 0
Read: Download Dissertation

Abstract


The development and production of rare earth permanent magnets start earlier inour country which are rich in rare earth resources, and the total output of our countryis leading in the world. In1996, the preparation of the Nd-Fe-Al bulk amorphousalloys successfully opened up a new field for the application of rare earth based bulkamorphous alloys in the hard magnetic materials due to its hard magnetic propertiesat room temperature and good glass forming ability. The development of this alloyhas important economic benefits to convert China’s rare earth resources advantagesinto industrial advantages. However, the hard magnetic mechanism of the Nd-Fe-Albulk amorphous alloys is still unclear to date.In this dissertation, vibrating sample magnetometer (VSM), differential scanningcalorimeter (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM),focused ion beam (FIB) and high resolution transmission electron microscopy(HRTEM) have been employed. The magnetic property, phase composition andmicrostructure of the Fe53Nd37Al10and Nd60Fe30Al10alloys with different coolingrates were investigated at different temperatures. The hard magnetic mechanism ofthe Fe-Nd-Al amorphous alloy is discussed in the reference with the typicalmagnetic model, and the results are summarized as follows:(1) All the samples of the Nd60Fe30Al10alloy show hard magnetic properties. Thecoercivity of the Nd60Fe30Al10alloy with thickness of1mm is highest. Thecoercivity of the ribbons is lower and decreases gradually with the increasingcooling rate. There are small steps in the hysteresis loops of the ribbons with5m/sand20m/s wheel speed.(2) The Fe53Nd37Al10alloy with thickness of1mm almost has soft magneticproperty at room temperature, with a small step in the hysteresis loop. There is noexchange coupling interaction in the as cast alloy. The5m/s-ribbon of theFe53Nd37Al10alloy shows the highest coercivity, with a step in the hysteresis loop.The exchange coupling interaction exists verified by the M Hcurve with twopositive peaks. The M Hcurve of the20m/s-ribbon has only one smallpositive peak. All the Fe53Nd37Al10ribbons show hard magnetic properties, and theircoercivity decrease gradually with the increasing cooling rate.(3) The coercivity of the1mm-thick Fe53Nd37Al10alloy almost remain constantwhile that of the ribbons increase obviously at low temperatures. All theFe53Nd37Al10ribbons exhibit exchange coupling interaction at low temperature, andthe peak value in the M Hcurve decreases with the increasing cooling rate.The5m/s-ribbon of the Fe53Nd37Al10alloy partially matches the pinning model, andthe step of the hysteresis loop is larger at lower temperature. Both the20m/s-and60m/s-ribbon of the Fe53Nd37Al10alloy match the pinning model, and their hysteresisloops show steps at low temperature. The ZFC and FC curves bifurcate at a certain low temperature, and the applied field essentially equals the sample’s coercivity atextremum temperature of the ZFC curve.(4) There are many lath-shaped Nd2Fe17crystals with different size embedding inthe amorphous matrix of the1mm-thick Fe53Nd37Al10alloy. A few of Nd crystalphases are apt to appear between two adjacent Nd2Fe17crystals. In the5m/s-ribbon,there are plenty of Nd2Fe17phases with5μm in size and clusters of5nm in diameterin the amorphous matrix. A lot of clusters of5nm in diameter are found in the20m/s-ribbon, while a few clusters of2nm in diameter exsit in the60m/s-ribbon.

Related Dissertations

  1. Study on the Effects of Element Substitution, Electronic Nematic Order and Domain Wall Pinning in Perovskite Manganites,O482.5
  2. Synthesis and Properties of Re-Fe Based Bulk Metallic Alloys,TG139.8
  3. Magnetic Property and Crystallinzation Behavior for Ferromagnetic Bulk Amorphous Alloys,TG139.8
  4. Cobalt and nickel and germanium - silicon thin film solid-phase reaction and Schottky contact characteristics,TN304
  5. Research on Magnetic Properties and Microstructure of Fe-Nd-Al Bulk Amorphous Alloys,TG139.8
  6. Investigations of Structure and Glass Forming Abilty of Amorphous Alloys,TG139.8
  7. Study on PMT Preparation, Structure and Performance of NiCoMnIn Alloy Foam,TG139.6
  8. Low-Frequency Magnetic Pulsing Effect as Well as EET Study of Amorphous Alloy Fe43Co43Hf7B6Cu1,TG139.8
  9. Effect of Thermal Deformation on the Structure and Magnetic Properties of Ni45Co5Mn36.7In13.3,TG139.6
  10. Fabrication and Characterization of Al-based Metallic Glass Thin Films,TG139.8
  11. The Effect of Heterogeneous Microstructure on the Room Temperature Mechanical Properties in Bulk Metallic Glass,TG139.8
  12. Research on the Constitutive Model of Zr-Based Metallic Glass and Extrusion Process of Micro Gears,TG139.8
  13. Study on Hydrogen Storage Properties and Preparation of Mg-Ti-Based Alloys,TG139.7
  14. Study on Hydrogen Storage and Electrochemical Performance of Re-Mg-Ni Based Compounds,TG139.7
  15. Hydrogen Storage and Electrochemical Properties of La-Mg-Ni Based Alloys,TG139.7
  16. Rare earth oxides and pore material modification NaAlH 4 Hydrogen absorption properties put,TG139.7
  17. An Investigation on the Structural and Electrochemical Properties of La15-x Ndx Fe14 Ni64 Mn5 B2 （x=0-6） Hydrogen Storage Alloys,TG139.7
  18. Investigation on the Phase Structure and Hydrogen Storage Characteristics of Ball-milled Mgx Ni100-x （x=70、60、50） Composite Hydrogen Storage Material,TG139.7
  19. Investigation on the Structure and the Kinetic Properties of Mg2 Ni-type Hydrogen Storage Alloys,TG139.7
  20. Microstructure and Martensitic Transformation of Ga-Mn-Ni-Co Alloys,TG139.6
  21. Structure and Shape Memory Effect of Ni-Mn-Ga-Gd High Temperature Shape Memory Alloys,TG139.6

CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > The alloy learn with a variety of properties of alloys > Other special nature of the alloy > Amorphous alloy
© 2012 www.DissertationTopic.Net  Mobile