Makine Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1944

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Nbmovta Refractory High-Entropy Alloy Incorporated Wni Matrix Composite as a Future Plasma-Facing Material: Evaluation of Mechanical Properties and Helium Ion Irradiation Behavior
(Elsevier Sci Ltd, 2025) Boztemur, Burcak; Filiz, Kaan; Karaguney, Zahide; Gokaydin, Eyupcan; Bozkurt, Yasin; Ozbasmaci, Ceren; Ovecoglu, M. Lutfi
Refractory high-entropy alloys (RHEAs) have gained attention in the last decades with their high mechanical strength, self-healing mechanism, and high irradiation resistance. These materials are evaluated to have a high potential as plasma-facing materials for fusion reactors. In this study, helium ion irradiation and mechanical behaviors of the RHEA-reinforced WNi matrix composites were investigated based on this perspective. Equimolar molybdenum, niobium, tantalum and vanadium powders were mechanically alloyed for 6 h to produce NbMoVTa RHEA with a single BCC phase. Then, different amounts (10, 20, 30, and 40 wt%) of RHEA were added into the W1Ni (containing 99 wt% W and 1 wt% Ni) matrix by planetary ball milling for 72 h. Consolidation was conducted by spark plasma sintering technique (1410 degrees C, 1 min). X-ray diffraction, scanning electron microscopy coupled with energy dispersion spectroscopy, and Archimedes' density analyses were performed on the composites. Moreover, wear and hardness properties of the composites were examined, and the lowest specific wear rate (0.59 mm3/N.m x 10- 5) and the highest hardness value (10.10 GPa) were found for the W1Ni-40RHEA composite. Helium irradiation was exposed to the composites to observe their irradiation resistance. It was observed that the lowest increment and the least deformation were obtained with the SPS'ed W1Ni-40RHEA composite. With the analysis of He+ irradiation, it was determined that the effect of radiation on mechanical properties is irrelevant. Also, it was observed that the addition of RHEA into the W matrix can create a high potential for using plasma-facing material. Moreover, it decreased the problems of tungsten against He+ irradiation.
Room-Temperature Synthesis of Refractory Borides: a Case Study on Mechanochemistry and Characterization of Mo-Borides and W-Borides
(Elsevier Sci Ltd, 2025) Süzer, İlayda; Akbari, Amir; Kaya, Faruk; Mertdinç Ülküseven, Sıddıka; Derin, Bora; Öveçoğlu, M. Lütfi; Ağaoğulları, Duygu
Mo-boride and W-boride powders were produced from native boron oxide, magnesium, and related metal oxide starting materials by mechanochemical synthesis (MCS) followed by an purification treatment. The reaction formation mechanisms and the products were predicted with the FactSageTM thermochemical simulation program. Different conditions were tested to determine the optimum synthesis parameters. MCS was conducted at stoichiometric ratios and different milling durations, using excess reactant amounts over the determined optimum time. After MCS, unwanted phases were removed by HCl acid leaching. Detailed phase analyses of the final powders were obtained by X-ray diffractometer (XRD), whereas detailed microstructure characterization was conducted by scanning electron microscope/energy dispersion spectrometer (SEM/EDS), transmission electron microscope (TEM) and particle size analyzer. Among the utilized parameters, the ideal composition chosen for Mo boride synthesis was 6 h milled and leached MoO3-100 wt% B2O3-50 wt% Mg (1.41 mu m), including alpha-MoB, beta-MoB, MoB2, Mo2B, Mo2B5, and Mo phases. For the synthesis of W boride, the proper composition was found as WO3-100 wt% B2O3-50 wt% Mg (0.37 mu m) containing W2B5, WB, beta-WB, WB4, W2B, and W phases after milling for 20 h and leaching. Besides, as a result of the oxidation resistance measurements at 700 and 800 degrees C, phases belonging to MoO2 and WO2 were found along with boride phases.

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Browsing Makine Mühendisliği Bölümü Koleksiyonu by Department "Mühendislik Fakültesi, Makine Mühendisliği"