Yazar "Motallebzadeh, Amir" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    Characterization of a copper matrix composite reinforced with nano/submicron-sized boron fabricated via spark plasma sintering
    (Elsevier ltd, 2024) Şahin, Rabia Tuğçe; Atak, Ömer Faruk; Burçak, Arda Baran; Jahangiri, Hadi; Motallebzadeh, Amir; Aydemir, Umut; Mohagheghi, Samira
    The addition of various reinforcing phases can improve the mechanical properties of copper. This study investigates the enhancement of the mechanical properties of copper by adding boron, focusing on overcoming the challenges associated with the homogeneous distribution of submicron/nanoscale secondary phases in metal matrix composites. Employing a combination of mechanical alloying and spark plasma sintering, a copper-boron composite containing 3 wt% boron was prepared. Scanning electron microscopy equipped with an electron backscatter diffraction detector and energy-dispersive X-ray spectroscopy was utilized to characterize the structure of the sintered samples and mechanically alloyed powder. A two-phase structure containing nano/submicron-sized boron distributed uniformly in the copper matrix was formed in the sintered sample. Instrumented micro-indentation tests were performed to characterize the mechanical behavior of the samples. The sintered composite sample exhibits significantly higher hardness than the sintered copper. The enhanced mechanical performance of the composite is primarily attributed to grain boundary strengthening and microstructural refinement, where nano/submicron-sized boron particles prevent grain growth and refine the microstructure, enhancing hardness and strength. Additionally, dispersion strengthening from hard boron particles and the presence of a high density of twin boundaries within the copper matrix increase resistance to dislocation motion and deformation, and further improving the material's mechanical properties. On the other hand, the composite sample exhibits increased electrical resistivity due to the boron's role as electron scattering centers. Overall, this study provides a valuable strategy for the design and optimization of advanced copper-based composites with tailored mechanical and electrical properties.
  • Küçük Resim
    Öğe
    Microstructure development and mechanical performance of Al2CrFeMnTi light-weight high entropy alloy
    (Elsevier Ltd, 2021) Jahangiri, Hadi; Mohagheghi, Samira; Asghari-Alamdari, Armin; Yilmaz, Rifat; Gürcan Bayrak, Kübra; Yu, Feng; Ghadbeigi, Hassan; Ayas, Erhan; Motallebzadeh, Amir
    Light-weight high entropy alloys (LWHEAs) are considered equiatomic or near-equiatomic alloys consisting of at least five elements. Low-density elements, like Al and Ti, are the key constituents in designing these alloys so that features such as reduced overall density and improved mechanical properties are achieved. A new LWHEAs (Al2CrFeMnTi) is designed, where mechanical alloying followed by subsequent casting is carried out for a successful synthesis. As a result, chemically homogenous samples are fabricated that possess a multiphase microstructure of BCC solid solution, C14 Laves phase, and L21 precipitates in the as-cast state. Although the presence of intermetallic phases results in high hardness characterized by nanoindentation tests, the produced alloy demonstrates some level of ductility before failure. This behavior could be linked to the minimal strain hardening of the BCC phase. Additionally, the formation of ultra-fine L21 precipitates within the BCC phase is contributed to the high strength and the modified strain observed in the alloy.