Yazar "Karakulak, Erdem" seçeneğine göre listele

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    Al/nbb2 in-situ kompozit üretimi ve özelliklerinin incelenmesi
    (2021) Demırtaş, Hüseyin; Karakulak, Erdem; Nadendla, Hari Babu
    Bu çalışmada in-situ yöntemi ile Al matriste NbB2 partikül takviyeli kompozitler üretilmiştir. Farklı\roranlarda partikül takviyesinin ve üretim süresinin kompozitler üzerindeki etkileri incelenmiştir. Oluşan\rpartiküller, boyutları ve dağılımları incelenmiş, tane boyutu ve sertliğe etkisi belirlenmiştir. Yapılan\rçalışmalar neticesinde partikül oluşumunda karıştırma süresinin kullanılan alaşım oranı gibi önemli\rolduğu belirlenmiş ve en iyi değerler 1,5 saat karıştırma sonucu oluşan %3,75 NbB2 ilaveli kompozitte\relde edilmiştir. Bu kompozitte tane boyutu 112 ?m seviyelerine inmiştir ve sertlik 306,4 MPa olmuştur.
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    Heat Treatment Conditions for High-Performance High-Pressure Die-Cast Al-Si-Cu-Mg Alloy
    (Wiley-V C H Verlag Gmbh, 2024) Demirtas, Hueseyin; Karakulak, Erdem; Babu, Nadendla Hari
    Random porosity in high-pressure die castings of aluminum alloys poses additional challenges in the form of blistering during follow-on heat treatment process. To avoid blisters, the current industrial practice is to lower solution temperature, but this compromises the strength. Herein, kinetics of eutectic Si spheroidization and coarsening during various solution treatment conditions and maximizing the dissolution of much needed Al2Cu and Al5Cu2Mg8Si6 phases, followed by formation of their precipitates in the aging stage with higher particle number densities, are studied and then higher tensile strength of 435 MPa in most commonly used high-pressure die-cast Al-Si-Cu-Mg alloy without causing blisters is demonstrated. Results on optimization of heat treatment of a high-pressure die-cast Al-Si-Cu-Mg alloy are presented. During solution treatment, dissolution of the intermetallic phases and disintegration/spheroidization of Si particles occur simultaneously. The optimized treatment results in higher strength compared to the published literature for similar alloys without causing any blisters which is a common problem faced in industry.image (c) 2023 WILEY-VCH GmbH
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    Production and characterization of in-situ Al-NbB2 composites
    (Elsevier, 2023) Demirtas, Huseyin; Karakulak, Erdem; Nadendla, Hari Babu
    We report here a melt processing route for the production of Al-NbB2 and Al-Cu-NbB2 in-situ composites in which fine NbB2 particles are uniformly distributed in Al matrix. During solidification, in-situ formed NbB2 phase in liquid Al contributed for enhanced heterogeneous nucleation, which caused a dramatic refinement of primary Al grain size, uniformly distributed second phases and enhanced wear characteristics.
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    Understanding the effect of Ni content on microstructure and mechanical properties of A384 HPDC alloy
    (Elsevier Science Sa, 2022) Demirtas, Huseyin; Karakulak, Erdem; Babu, Nadendla Hari
    Investigations have been carried out to understand the correlation between Ni content and properties of HPDC cast A384 aluminium alloy in as-cast and heat-treated conditions. Depending on Ni content in the alloy, different Ni-bearing intermetallics were formed. Suitable heat treatment conditions were selected after a series of experiments to obtain optimal mechanical properties. Most of the Ni containing inter-metallics found to be stable at solutionizing temperatures which have a dramatic effect on the mechanical properties of alloys after natural and artificial aging. The results showed that, after heat treatment, to achieve higher strength values lower Ni additions are favourable. (c) 2021 Published by Elsevier B.V.