Malzeme Bilimi ve Mühendisliği Bölümü

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Citation - Scopus: 1
Fragmentation and Coulomb explosion of multicharged small boron clusters
(2012) Tas, M.; Akman, N.; Özdoǧan, C.; Boustani, I.; 40569
We extensively study the fragmentation and Coulomb explosion of multiply charged small boron clusters B n (n=2-13), where n is the cluster size. Our calculations are based on ab initio quantum-chemistry methods. Highly charged unstable clusters dissociate spontaneously into several neutral or charged fragments, and large amounts of energy are produced, depending on the charge of the parent cluster. We argue that this mechanism makes boron clusters a clean, safe, and cheap energetic material. © 2012 American Physical Society.
Microstructure and Mechanical Properties of CoCrFeNi(TiAl) High Entropy Alloys
(2020) Kalay, İlkay; Kalay, Ilkay; 101579; Mekatronik Mühendisliği
The structure and mechanical properties of CoCrFeNi and CoCrFeNiTi0.5Al0.5 (in molar ratio) high entropy alloys were investigated using X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM), hardness and compression tests.With the addition of Ti and Al, the crystal structure of CoCrFeNi changed from FCC to amixture of FCC and double BCC structures. The lattice parameter of FCC increasesupon addition of Al and Ti. The microstructure analysis shows the morphologicaltransition of dendrites from non-equiaxed to equiaxed during the suction casting ofCoCrFeNiTi0.5Al 0.5 alloy. The Vickers microhardness testing of CoCr-FeNi alloy revealssignificant increase in hardness with the addition of Al and Ti. The hardness values areimproved in as-suction cast CoCrFeNi and CoCrFeNiTi0.5Al 0.5 alloys compared to their ascast alloys due to strengthening. The CoCrFeNiTi0.5Al 0.5 alloy yields at 1997 MPa and failsat 2344 MPa. The fracture mechanism of CoCrFeNiTi0.5Al 0.5 alloy reveals a cleavage mode.
Citation - WoS: 203
Citation - Scopus: 212
Stability of edge states and edge magnetism in graphene nanoribbons
(Amer Physical Soc, 2011) Kunstmann, Jens; Özdoğan, Cem; Ozdogan, Cem; Quandt, Alexander; Fehske, Holger; Ortak Dersler Bölümü
We critically discuss the stability of edge states and edge magnetism in zigzag edge graphene nanoribbons (ZGNRs). We point out that magnetic edge states might not exist in real systems and show that there are at least three very natural mechanisms-edge reconstruction, edge passivation, and edge closure-which dramatically reduce the effect of edge states in ZGNRs or even totally eliminate them. Even if systems with magnetic edge states could be made, the intrinsic magnetism would not be stable at room temperature. Charge doping and the presence of edge defects further destabilize the intrinsic magnetism of such systems.

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