Title page for etd-0514113-133259


[Back to Results | New Search]

URN etd-0514113-133259
Author Guan-Lin You
Author's Email Address No Public.
Statistics This thesis had been viewed 5358 times. Download 315 times.
Department Materials and Optoelectronic Science
Year 2012
Semester 2
Degree Ph.D.
Type of Document
Language English
Title In situ synthesis of nanoparticles reinforced Al-based composites from Al-SiO2, Al-CuO and Al-Mg-CuO systems by friction stir processing
Date of Defense 2013-05-31
Page Count 113
Keyword
  • Al-SiO2
  • Aluminum based composite
  • Al-Mg-CuO
  • Al-CuO
  • Friction stir process
  • In situ composite
  • Abstract Aluminum matrix composites reinforced with nanometer-sized particles were produced from powder mixture of Al and oxides by using friction stir processing (FSP). This approach combined the hot working nature of FSP and exothermic reactions between Al and oxides. In this study, composites synthesized from Al-SiO2, Al-CuO and Al-Mg-CuO were investigated, and the microstructure and mechanical properties of the composites were characterized.
    In the Al-SiO2 composites, Al2O3 particles were produced in situ by oxide-aluminum displacement reactions. The Al2O3 particles were formed at the Al/SiO2 interface, and dispersed in the aluminum matrix by the stirring action of the rotating tool during FSP. Microstructural examinations revealed the Al2O3 particles present mainly in the form of clusters of nano-sized (approximately 20 nm) particles, which were identified as α-Al2O3. Because of the fine dispersion of nano-sized particles in an ultrafine-grained aluminum matrix, the composites exhibit superior tensile strength and ductility. Quantitative phase analysis indicated that the extent of the Al-SiO2 reaction increased in conjunction with an increasing tool rotation rate and a decreasing tool traverse speed in FSP.
    In the Al-CuO composite, the in situ formed reinforcements include nanometer-sized Al2O3 and Al2Cu particles. These Al2O3 nano-particles were identified as amorphous in the as-FSPed condition. The average Al grain size in the FSPed composite was approximately 1 μm. The composite exhibited enhanced strength. The major contributions to the high strength of the composite are the ultrafine grained structure of aluminum matrix and the fine dispersion of nanometer-size reinforcing particles inside aluminum grains.
    Aluminum based in situ composite was synthesized from powder mixture of Al/Mg/CuO by using friction stir processing (FSP). Microstructure characterization indicates that in situ formed MgO and Al2Cu nano-particles are uniformly distrubuted in submicron-grained aluminum matrix. Because of the large amount of nanometer-size reinforcements in a submicron-grained matrix, the composite exhibits superior Young’s modulus and strength. The reaction mechanism responsible for the in situ formation of MgO and Al2Cu particles in FSP is discussed. This work has demonstrated the beneficial effect of utilizing the Mg/metal-oxide displacement reaction in the synthesis of aluminum based in situ composite.
    Advisory Committee
  • New-Jin Ho - chair
  • Chung-Yi Yu - co-chair
  • Liu-wen Chang - co-chair
  • Ker-Chang Hsieh - co-chair
  • Shuei-Yuan Chen - co-chair
  • Po-We Kao - advisor
  • Files
  • etd-0514113-133259.pdf
  • Indicate in-campus at 3 year and off-campus access at 3 year.
    Date of Submission 2013-06-14

    [Back to Results | New Search]


    Browse | Search All Available ETDs

    If you have more questions or technical problems, please contact eThesys