Dissertation > Excellent graduate degree dissertation topics show

Fabrication and Synthesization of Bulk Ultrafine-Grained/Nanostructured Light Metals

Author: BianLiPing
Tutor: LiangWei
School: Taiyuan University of Technology
Course: Materials Processing Engineering
Keywords: ultrafine grained microstructure nanocrystalline bulk nanostructured materials severe plastic deformation equal channel angular pressing
CLC: TB383
Type: Master's thesis
Year: 2004
Downloads: 201
Quote: 1
Read: Download Dissertation

Abstract


Nanostructured metallic materials attract great attention from scientific research field due to their peculiar microstructures and physical, mechanical and chemical properties and the great potential for practical applications. In this paper, nanostructured Mg-5w%Al-10.3w%Ti alloy has been fabricated by mechanical alloying and ultrafme-grained bulk pure Al and Al-3%Cu alloy by equal channel angular pressing(ECAP).Nanostructured Mg-5w%Al-10.3w%Ti alloy was prepared by mechanical alloying with the powder mixture of Mg. Al, Ti and process control agent of polyethylene-glycol (H(OCH2CH2)nOH). Compared to conventional powder metallurgy, the mechanical property of the sample synthesized by mechanical alloying shows peculiar strain-softening. TEM analysis shows that the average grain size of the alloy is 20-30nm. Besides, several grains about 90nm and many nanotubes about 3~7nm in diameter are observed.ECAP experiments were conducted on pure Al and Al-3%Cu alloy. The microstructural evolution during ECAP and the influence factors, mechanichal property and the stability of the microstructure of pure Al and Al-3%Cu were investigated. The pure Al was refined from 1.0mm to 0.48μm by ECAP. The refinement saturated after EGA Pressing for 8 passes, corresponding to a maximum hardness value. It was found that such a refined microstructure is stable even after annealing at 150℃ for 1 h. The conventional compression test showed that the as-ECA Pressed sample exhibits a much higher yield strength and a higher strain hardening rate than the unECA Pressed sample. Decreasingtemperature of EGA pressing in pure Al promotes the refinement. Equiaxed grains with high angle grain boundaries are obtained just for 4 passes by EGA Pressing at the lower temperature, in contrast to 8 passes at room temperature. Al-3%Cu alloys as-solid-solutioned and as-aged are subjected to EGA Pressing. The results of TEM analysis and hardness test showed that quantities of coherent particles precipitated in the single-phase solid solution after ECAP for 6 passes, however, its refinement effect is not as significant as that of two-phase alloy after equal passes, in which a large number of incoherent precipitates promote the refinement of ECAP and the strain hardening rate.

Related Dissertations

  1. Electroless Ni-Pon the Bulk Nanocrystalline Ingot Iron,TQ153.1
  2. Preparation and Characterization of Doped BiFeO3 Nanocrystals,TB383.1
  3. Hydrogenated nanocrystalline silicon photovoltaic materials in hydrogen bonding defects in material structure and the impact of,TB383.1
  4. Porous electrode material of vanadium pentoxide Synthesis, Characterization and Properties,O614.511
  5. Polymorphous polyphosphazene micro Nanomaterials and functional applications to explore,TB383.1
  6. Preparation of phase separation of the amorphous silicon oxide and nanocrystalline silicon mosaic silica,TN304.1
  7. The tissue homogenization the synthesis reaction AgSnO_2 material process materials stress state,O482.1
  8. Pressure Extrusion Formation and Soft Magnetic Properties Study of Composite Magnetic Powder Cores,TF124.39
  9. Structure and Magnetic Properties of FeCuNb (Ti) SiB,TG139.8
  10. DNA template to guide the preparation of noble metal nanoparticles and applied research,TB383.1
  11. Study on the Nanocrystalline MgAl2O4 Spinel Powder Prepared by Microwave-assisted Low-temperature Combustion Synthesis Technology,TB383.1
  12. Synthesis and Photovoltaic Properties Research of Triphenyl Amine Dyes,TM914.4
  13. Modification and Photoelectrochemical Research Based on Nanocrystalline TiO2 Photoanode,TM914.4
  14. Research on Amorphous and Nanocrystalline Soft Magnetic Dynamic Measurement System Based on Virtual Instrument,TM271.2
  15. Research and Development of the Inductance Measuring Meters of Amorphous and Nanocrystalline Soft Magnetic Materials,TM271.2
  16. Corrosion Behavior of Bulk Nanocrystalline 304 Stainless Steel,TG172
  17. Manufacturing, Crystallization and Soft Magnetic Properties of Fe-based Amorphous and Nanocrystal Alloys,TG139.8
  18. Study on the Microstructures and Mechanical Properties of Mg-Zn-Si Alloys Processed by ECAP,TG379
  19. Microstructure and Mechnaical Property of High-Mg2Si Al-Mg-Si Alloys by Severe Plastic Deformation,TG146.21
  20. Study on Microstructures and Properties of Mg-Al-Nd Alloys after Equal Channel Angular Pressing,TG379
  21. Effects of Stress Amplitude and Temperature on Fatigue and Damage Behaviour of Ultrafine-Grained Copper,TG146.11

CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
© 2012 www.DissertationTopic.Net  Mobile