Dissertation > Excellent graduate degree dissertation topics show

Crystallization Behavior of Zr-based Bulk Amorphous Alloys

Author: WangBo
Tutor: HeShunRong
School: Hefei University of Technology
Course: Materials Processing Engineering
Keywords: Zr-based bulk amorphous ally crystallization kinetics thermal stability crystallization type phase transformation
CLC: TG139.8
Type: Master's thesis
Year: 2009
Downloads: 144
Quote: 1
Read: Download Dissertation

Abstract


In this thesis, crystallization behavior of Zr60Al15Ni25, Zr55Al10Ni5Cu30,Zr65Al10Ni10Cu15 and Zr52.5Al10Ni10Cu15Be12.5 amorphous alloys have been systematically investigated by XRD and DSC.In this first part of the thesis, a historic progress of bulk amorphous alloys has been critically overviewed, and narrate the excellent properties and production methods of amorphous alloy shortly, lastly introduce crystallization approach, crystallization types, crystallization thermodynamics and crystallization kinetics particularly.Different scanning calorimeter （DSC） was used to investigate non-crystallization kinetics of Zr60Al15Ni25,Zr55Al10Ni5Cu30 and Zr65Al10Ni10Cu15 amorphous alloys, the results show that glass formation ability and crystallization of amorphous alloys also relate to heating rate, and it had a dynamic effect. Kissinger equation and Ozawa equation were used to calculate the activation crystallization energy（Eg,Ex and Ep）, resulting in a small deviation between them, and Eg of the alloys are higher than Ex and Ep. In isothermal condition, JMA equation was used to calculate the activation energy （Ec） of amorphous alloy, the results show that addition of Cu can improve the thermal stability of the Zr-based alloy, and addition of 15at% Cu is more availability than addition of 30at% Cu. In addition, the values of Avrami exponent which also obtained by JMA equation show that the crystallization of Zr60Al15Ni25 is polymorphic crystals with a decreasing nucleation rate for the former and controlled by the interface, and crystallization of Zr55Al10Ni5Cu30 and Zr65Al10Ni10Cu15 are similar, with a decreasing nucleation rate for the former and controlled by the volume diffusion. Different scanning calorimeter （DSC） was used to investigate crystallization kinetics of Zr52.5Al10Ni10Cu15Be12.5 amorphous alloy, which can in contrast with crystallization of Zr65Al10Ni10Cu15. The result shows that the thermal stability of Zr52.5Al10Ni10Cu15Be12.5 alloy is higher than Zr65Al10Ni10Cu15, and the addition of Be element can improve the thermal stability of the Zr-based alloy, which also can be made firm by anneal experiment.X-ray diffraction was used to investigate crystallization of Zr65Al10Ni10Cu15 and Zr52.5Al10Ni10Cu15Be12.5 alloy. The results show that Zr65Al10Ni10Cu15 amorphous alloy was annealed at different conditions, metastable phase Zr2Ni and other Zr-Al,Zr-Cu compounds were precipitated in the amorphous matrix first, and the crystallized phases Zr2Cu,Zr2Al3 and other compounds were produced later; Zr52.5Al10Ni10Cu15Be12.5 amorphous alloy was annealed at different conditions, ZrCu,ZrBe2,Zr2Al3 main crystallized phases were precipitated in the amorphous matrix. With the addition of Be element, the Zr-Ni metastable compound is inhibited precipitating. Integrated them with results of crystallization kinetics, it indicates that the crystallization of Zr65Al10Ni10Cu15 and Zr52.5Al10Ni10Cu15Be12.5 is also with a decreasing nucleation rate for the former and controlled by the volume diffusion, but crystallization types is different, and Zr65Al10Ni10Cu15 is the initial crystallization process, and the crystallization of Zr52.5Al10Ni10Cu15Be12.5 alloy is eutectic type. The addition of Beryllium influences nucleation and growth of crystallization of amorphous alloy, and lead to the transition of crystallization type.

Related Dissertations

  1. Thermal Stability of Complexes of Chitosan Quaternary Ammonium Salt and Metal Ion,O634
  2. Study on the Synthesis and Properties of Poly(1,4-Cyclohexyledimethylene Terephthalate) (PCT),TQ323.4
  3. Syntheses, Structures and Properties of Metal-organic Frameworks Based on Dicarboxylate Ligands,O621.13
  4. Imidazolium ionic liquids Thermal Analysis,O626.23
  5. Study on Influence of Preferred Orientation on Mechanical and Recoverable Properties of TN479 Shape Memory Alloy Sheet,TG139.6
  6. Study on Microstructure and Properties of Deformation Processed Cu-Fe in Situ Composites,TB331
  7. Synthese, Structureand Characterization of Transition Metalcomplexes with Heterocyclic Carboxylic Ligands,O621.13
  8. Production and Purification of a Thermostable Cyclodextrin Glycosyltransferase with a High Starch Hydrolytic Activity from Bacillus Licheniformis SK13.002 and Its Application for β-Cyclodextrin Production,TQ28
  9. Surface Integrity in Hard Milling H13 Steel,TG54
  10. Syntheses, Structures and Properties of Coordination Compounds Based on Symmetrical Imidazole Dicarboxylic Acid and Asymmetric Nitrogen Heterocyclic Flexible Ligands,O621.13
  11. Synthesis、 Structures and Characters of Transition Metal Coordination Polymers of Bis (Methylbenzimidazole) Flexible Ligand,O621.13
  12. Through site-directed mutagenesis of methyl parathion hydrolase improve the thermal stability of MPH,X592
  13. Poly(aryl-Ether-Ketone) with Norbornene Ring: Synthesis and Properties,O631.3
  14. Simulation Study on Active Comprehensive Compensation of Traction Substation,TM922.4
  15. The Study on Structure and Properties Relationship of Fe-based Imidazolium Ionic Liquids as Desulfurizing Agents,X701.3
  16. The Influence and Reacitive Crystallization Kinetics of Nesquehonite,TQ132.2
  17. Study of the Preparation and Photo-Activity of Novel Polycyclic Aromatic Ferrocenium Salts,O627.81
  18. Reinforced polyethylene terephthalate composites , structure and properties of,TB332
  19. Study on Solid State Reaction of Metal/SiGe and Its Contact Characteristics,TN304
  20. Synthesis and Application of the chloro- methoxy fatty acid methyl esters,TQ414.8
  21. Investigation on Structure and Properties of New Hot Work Die Steel,TG142.1

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