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1

Correlation of Hardness and Silicon Morphology for Al-Si-Sb Alloy

Uzun O., Yilmaz F., Emeksiz C., Ergen S., Kolemen U.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

467--472

EN

In this study, we have focused on the role of silicon morphology on the hardness of eutectic Al–12 wt.% Si–0.5 wt.% Sb alloy solidified at different cooling rates. The alloys were produced by using induction melting, arc-remelting and melt-spinning techniques. The cooling rates of the alloys were determined as 0.5, 60 and ~105°C.s-1 for induction-melted, arc-remelted and meltspun alloy. The experimental results show that as the cooling rate increased the coarse silicon phase was substantially refined and its morphology altered from sharp need-like to round shape. Two exothermic peaks, attributed to precipitation and coarsening of silicon from supersaturated α-Al, were observed in the DSC curve of MS alloy. Vicker’s hardness of melt-spun alloy was found two times higher than those of IMed and ARed alloys. The lowest hardness of induction-melted alloy was ascribed to the lamellar morphology of silicon, yielding decohesive rupture. This result was confirmed by finite element analyzing.

2

Characterization of Cu and Ni Nano-Fluids Synthesized by Pulsed Wire Evaporation Method

Kim H.-S., Yilmaz F., Dharmaiah P., Lee D.-J, Lee T.-H., Hong S.-J.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

999--1004

EN

In the present work, Cu and Ni nanofluids were synthesized using the pulsed wire evaporation (PWE) method in the different aqueous medias, namely (ethanol and ethylene glycol), and the effects of the aqueous media on the dispersion state, stability, and particle size of nanoparticles were studied. The size and morphology of synthesized nano-particles were investigated by transmission electron microscopy (TEM). Also, the dispersion stability of the nanofluids was evaluated by turbiscan analysis. The TEM results showed that the nano-particles were spherical in shape, and the average particle size was below 100 nm. The average particle size of the Cu nano-particles was smaller than that of Ni, which was attributed to a difference in the specific sublimation energy of the elements. Moreover, ethylene glycol (EG) exhibited higher suspension stability than ethanol. Finally, the dispersion stability of Cu@EG displayed the highest value due to lower particle size and greater viscosity.

3

Mechanical Properties and Melt Quality Relationship of Sr-modified Al-12Si Alloy

Uludağ M., Uyaner M., Yilmaz F., Dişpinar D.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4

134--140

EN

The formation of oxide film on the surface of aluminium melts, i.e. bifilms, are known to be detrimental when they are incorporated into the cast part. These defects causes premature fractures under stress, or aid porosity formation. In this work, Al-12 Si alloy was used to cast a step mould under two conditions: as-received and degassed. In addition, 10 ppi filters were used in the mould in order to prevent bifilm intrusion into the cast part. Reduced pressure test samples were collected for bifilm index measurements. Samples were machined into standard bars for tensile testing. It was found that there was a good agreement with the bifilm index and mechanical properties.