Production and characterization of alumminum-rare earth based bulk amorphous/nanocrystalline composite

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2016

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Kutsal, Mustafacan

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The structure, production and consolidation of binary Al-RE (RE=Sm, Tb) and multicomponent Al-RE-TM (TM= Fe, Ni, Cu) metallic glasses were studied mainly in two parts. In the first part, solid-state amorphous structures of melt-spun and magnetron sputtered thin films of Al90Tb10 were investigated with high energy X-ray diffraction (HEXRD) constrained reverse Monte Carlo (RMC) simulations. The experimental findings and calculated models had shown that amorphous alloys having the same composition comprises the same atomic arrangement in short-range order (SRO) scale, yet have distinctly differing structures in medium-range (MRO) scale. In the second part of the study, amorphization of Al-RE and Al-RE-TM based alloys with mechanical milling and alloying were studied. It was found that binary and quaternary compositions of Al-RE systems had strong resistance against vitrification through mechanical milling. However, partial amorphization in Al-RE-TM and Al-RE-TM1-TM2 systems were achieved with mechanical alloying. Characterization of mechanically alloyed Al85Sm7Fe5Ni3 powders had revealed the structure is not fully disordered but comprise an amorphous/nanocrystalline structure, consisting of amorphous phase, fcc-Al nanocrystals and unknown intermetallic phase with spherical morphology. Consolidation of mechanically alloyed Al85Sm7Fe5Ni3 powders were studied with pressing and sintering, and warm pressing. The effect of ex-situ composite formation with the mechanically alloyed powders mixed with pure Al powders on mechanical properties of the bulk structures were also investigated. Mechanical characterization of the bulk amorphous/nanocrystalline and ex-situ composite consolidates were performed, together with their post-mortem failure analyses.

Subject Keywords

Nanocrystals., Aluminum alloys., Rare earth metals., Metallic composites., Amorphous substances.

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http://etd.lib.metu.edu.tr/upload/12620094/index.pdf
https://hdl.handle.net/11511/25745

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

M. Kutsal, “Production and characterization of alumminum-rare earth based bulk amorphous/nanocrystalline composite,” M.S. - Master of Science, Middle East Technical University, 2016.