Istanbul TechnicalUniversity, Metallurgical And Materials Engineering, PhD
RESEARCH, TEACHING, or OTHER INTERESTS
General Materials Science, Ceramics and Composites, Metals and Alloys, Materials Science
16
Scopus Publications
223
Scholar Citations
10
Scholar h-index
10
Scholar i10-index
Scopus Publications
Growth and characterization of carbon nanotubes on FeSi substrates via chemical vapor deposition: influence of synthesis parameters and magnetic properties D. Kavrar-Ürk, D. Ovalı-Döndaş, E. Okumuş, H. Ağırcan, M. Y. Seyidov, H. Cebeci, M. L. Öveçoğlu Journal of Materials Science Materials in Electronics, 2026 FeSi powders were investigated as a dual-function substrate–catalyst for carbon nanotube (CNT) synthesis via chemical vapor deposition (CVD), offering an alternative to conventional transition metal catalysts deposited on inert oxide supports. Unlike Fe, Co, or Ni nanoparticles on SiO 2 or Al 2 O 3 , which require separate deposition steps and often suffer from aggregation, FeSi provides an in-situ source of catalytically active Fe atoms within a thermally stable silicide matrix. Multi-walled CNTs were synthesized at 800 ºC using ethylene (C 2 H 4 ) at flow rates of 400–1000 sccm. SEM and TEM analyses revealed CNT diameters ranging from 33.55 to 48.55 nm, with the number of walls estimated at 34 ± 6. Raman spectroscopy showed $${I}_{\\text{G}}/{I}_{\\text{D}}$$ I G / I D ratios of 1.11–1.29, indicating good graphitic quality with low defect density. Magnetic measurements at 10 K and 300 K confirmed superparamagnetic behavior with zero coercivity, attributed to nanoscale Fe-containing particles encapsulated within the CNT structure. The saturation magnetization decreased from ~ 20 emu/g (pristine FeSi) to ~ 9–15 emu/g (CNT-FeSi composites) due to carbon mass dilution. This work demonstrates that FeSi powders can serve as an effective substrate–catalyst system for CNT growth, eliminating the need for external catalyst deposition while providing in-situ generated superparamagnetic properties.
Powder Metallurgical Processing of Al–5 wt% Cu Matrix Composites Reinforced with MoSi2 and WSi2 Particulates Sıddıka Mertdinç‐Ülküseven, Didem Ovalı‐Döndaş, İlayda Süzer, Mert Altıntaş, Murat Can Karaca, Bahadır Özal, Duygu Ağaoğulları, Mustafa Lütfi Öveçoğlu Advanced Engineering Materials, 2025 Herein, investigations on the microstructural, physical, and mechanical properties of molybdenum disilicide (MoSi2)‐ and tungsten disilicide (WSi2)‐reinforced aluminum (Al)–copper (Cu) matrix composites are reported. Powder metallurgy methods such as mechanochemical synthesis (MCS), mechanical alloying (MA), cold pressing, and pressureless sintering are combined to produce composites. First of all, MoSi2 and WSi2 nanoparticles are synthesized by MCS and selective acid leaching, yielding reinforcement materials for Al–Cu matrix. Powder blends consisting of 95 wt% Al and 5 wt% Cu are mixed with metal disilicides at different weight percentages (1, 2, and 5 wt%). MA for 4 h is conducted on these overall blends using a high‐energy ball mill. Microstructural and thermal properties of the as‐blended and mechanically alloyed powders are determined, and then they are compacted under 450 MPa and sintered at 550 °C for 2 h. Mechanical characterization of the composites reveals an increase in hardness and wear resistance with an increasing amount of reinforcement content. Among bulk samples, 5 wt% WSi2‐reinforced composites have the highest microhardness (165 ± 15 HV) and lowest wear rate (1.69 × 106 μm3 Nm−1) values. However, under the compression forces, the highest toughness and strength are obtained from 2 wt%‐reinforced composites.
Co-synthesis of zirconium boride/silicide/oxide composite powders by magnesiothermic reduction Didem OVALI DÖNDAŞ Journal of Boron, 2022 This study uses a magnesiothermic reduction method to investigate the co-synthesis of zirconium boride, silicides, and oxide powder composites using ZrO2, B2O3, Si, and Mg initial powders. The synthesis of high-temperature ceramic powders is examined through milling durations, reduction temperatures, and excess magnesium addition. Thermochemical analysis of probable reaction products was conducted by the Factsage software. According to the results, the thermochemical predictions and resultant powder phases showed good coherency. High-energy milling has a significant effect on the formation of the zirconium boride phase after annealing. However, extended milling time and higher annealing temperature have no significant effects on the composition of the constituted composite powders according to the X-ray diffraction results. An annealing temperature of 600 ºC was enough to obtain ZrB2-based ceramic composite powders. In the final powder phases, the excess magnesium addition to the stoichiometric displays an important feature. After the milling, annealing, and leaching procedure, the stoichiometric powder composition comprises ZrB2, ZrSi, ZrSi2, ZrO2, and MgSiO2, and excess Mg added powders have the ZrB2, ZrSi, ZrSi2, ZrO2 phases in their structure. Scanning electron microscopy analysis was utilized to observe the morphologies of the powders throughout each step of the synthesis procedure and revealed the finely structured morphology of synthesized powders.
Effects of oxide particles on the microstructural and mechanical properties of W-Ni-WB composites Didem Ovalı, Özge Balcı, Duygu Ağaoğulları, M. Lütfi Öveçoğlu Particulate Science and Technology, 2020 This study reports the effect of La2O3 addition on the microstructural and some mechanical properties of the W-Ni-WB composites. Composites having the compositions of W – 1 wt% Ni – 2 wt% WB and W – 1 wt% Ni – 2 wt% WB – x wt% La2O3 (x = 0.5 and 1) were fabricated by mechanical alloying (MA) and activated sintering methods. Phase and microstructural characterizations of the mechanical alloyed powders and sintered samples were carried out using X-ray diffractometer, scanning electron microscope (SEM), particle size analyzer and electron probe microanalyzer. Archimedes density and microhardness measurements, and sliding wear tests were also conducted on the sintered samples. The results showed that 1 wt% addition of La2O3 particles yields the lowest average particle size (290 nm) with a homogeneous particle size distribution of the composite powders. The sinterability and wear resistance of the composites, and the distribution of the particles throughout the sintered microstructure were also improved by adding oxide dispersoids into the W-Ni-WB composites. MA’d and sintered W – 1 wt% Ni – 2 wt% WB, – 1 wt% La2O3 composite had the relative density, average microhardness, and wear volume loss values of 96.97%, 6.02 GPa, and 115.8 µm3, respectively.
HCREEP behaviour of PP/CNT nanocomposites: An experimental study validated with creep model Eccm 2016 Proceeding of the 17th European Conference on Composite Materials, 2016
Growth and characterization of carbon nanotubes on FeSi substrates via chemical vapor deposition: influence of synthesis parameters and magnetic properties D Kavrar-Ürk, D Ovalı-Döndaş, E Okumuş, H Ağırcan, MY Seyidov, ... Journal of Materials Science: Materials in Electronics 37 (10), 775 , 2026 2026.0
Room-temperature mechanochemical synthesis of SiC-based ceramic powders D OVALI-DÖNDAŞ Ceramics International , 2025 2025.0 Citations: 1
Powder Metallurgical Processing of Al–5 wt% Cu Matrix Composites Reinforced with MoSi2 and WSi2 Particulates S Mertdinç‐Ülküseven, D Ovalı‐Döndaş, İ Süzer, M Altıntaş, ... Advanced Engineering Materials, 2400622 , 2024 2024.0 Citations: 2
Co-synthesis of zirconium boride/silicide/oxide composite powders by magnesiothermic reduction D Ovalı-Döndaş Journal of Boron 7 (4), 552-559 , 2022 2022.0 Citations: 1
Spark plasma sintering of molybdenum silicides synthesized from oxide precursors D Ovalı, M Tarraste, M Kaba, D Ağaoğulları, L Kollo, KG Prashanth, ... Ceramics International 47 (10), 13827-13836 , 2021 2021.0 Citations: 11
Effects of oxide particles on the microstructural and mechanical properties of W-Ni-WB composites D Ovalı, Ö Balcı, D Ağaoğulları, ML Öveçoğlu Particulate Science and Technology 38 (3), 347-353 , 2020 2020.0 Citations: 5
Polyamide 12/Antimony Trioxide/Sepiolite or Boron Composites: Mechanical Properties and Flame Retardancy A ÖZTÜRK, F SARIBAL, Ş DUMAN, M AKKOYUN, ŞEN İ̇brahim, ... Çukurova Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi 35 (4), 1083-1090 , 2020 2020.0 Citations: 4
Characterization of mechanically alloyed and pressureless sintered Al-7 wt% Si-2 wt% LaB6-2 wt%(MoSi2, WSi2) hybrid composites E Tekoğlu, Y Yürektürk, D Ağaoğulları, D Ovalı, S Mertdinç, ML Öveçoğlu Advanced Powder Technology 30 (11), 2626-2635 , 2019 2019.0 Citations: 15
Room-temperature synthesis of tungsten silicide powders using various initial systems D Ovalı, D Ağaoğulları, ML Öveçoğlu International Journal of Refractory Metals and Hard Materials 82, 58-68 , 2019 2019.0 Citations: 13
Effects of the matrix crystallinity, dispersed phase, and processing type on the morphological, thermal, and mechanical properties of polylactide‐based binary blends with poly … M Nofar, H Oguz, D Ovalı Journal of Applied Polymer Science 136 (23), 47636 , 2019 2019.0 Citations: 44
Mechanochemical synthesis and characterisation of niobium silicide nanoparticles D Ovalı, D Ağaoğulları, ML Öveçoğlu Ceramics International 45 (8), 10654-10663 , 2019 2019.0 Citations: 10
Development of PLA-PBAT and PLA-PBSA bio-blends: Effects of processing type and PLA crystallinity on morphology and mechanical properties MN H Oguz, C Dogan, D Kara, ZT Ozen, D Ovali AIP Conference Proceedings 2055 (1), 030003 , 2019 2019.0 Citations: 25
TiB2 ve La2O3 Partikül Takviyelerinin Mekanik Alaşımlama ve Aktifleştirilmiş Sinterleme ile Üretilen Volfram Matrisli Kompozitler Üzerindeki Etkisinin İncelenmesi D Ağaoğulları, Ö Balcı, H Gökçe, D Ovalı, ML Öveçoğlu Akademik Platform Mühendislik ve Fen Bilimleri Dergisi 7 (1), 95-105 , 2019 2019.0 Citations: 1
Characterization of SiO2-encapsulated WSi2/W5Si3 nanoparticles synthesized by a mechanochemical route D Ovalı, D Ağaoğulları, ML Öveçoğlu Ceramics International 44 (8), 9442-9453 , 2018 2018.0 Citations: 19
Effect of tungsten disilicide addition on tungsten boride based composites produced by milling-assisted pressureless sintering D Ovalı, D Ağaoğulları, H Gökçe, ML Öveçoğlu Journal of Boron 3 (1), 42-50 , 2018 2018.0 Citations: 2
Effects of excess reactant amounts on the mechanochemically synthesized molybdenum silicides from MoO3, SiO2 and Mg blends D Ovalı, D Ağaoğulları, ML Öveçoğlu International Journal of Refractory Metals and Hard Materials 65, 19-24 , 2017 2017.0 Citations: 11
Investigation of Mechanochemical Synthesized Tungsten Silicides from WO 3 , SiO 2 and Mg Blends D Ovalı, ML Ovecoglu Solid state phenomena 257, 47-51 , 2017 2017.0 Citations: 5
In situ synthesis of NbB2–NbC composite powders by milling-assisted carbothermal reduction of oxide raw materials Ö Balcı, D Ağaoğulları, D Ovalı, ML Öveçoğlu, I Duman Advanced Powder Technology 26 (4), 1200-1209 , 2015 2015.0 Citations: 43
Photocatalytic Efficiency of ZnO/TiO 2 Composite Plates in Degradation of RR180 Dye Solutions M Konyar, D Ovali, HC Yatmaz, C Duran, K Öztürk Advances in Science and Technology 65, 244-250 , 2011 2011.0 Citations: 11
Exploring Fesi as a Substrate: Catalyst for Tailored Carbon Nanotube Synthesis and Their Magnetic Behaviors D Kavrar Ürk, D Ovalı-Döndaş, E Okumuş, H Ağırcan, MY Seyidov, ... Elsevier BV , 0
MOST CITED SCHOLAR PUBLICATIONS
Effects of the matrix crystallinity, dispersed phase, and processing type on the morphological, thermal, and mechanical properties of polylactide‐based binary blends with poly … M Nofar, H Oguz, D Ovalı Journal of Applied Polymer Science 136 (23), 47636 , 2019 2019.0 Citations: 44
In situ synthesis of NbB2–NbC composite powders by milling-assisted carbothermal reduction of oxide raw materials Ö Balcı, D Ağaoğulları, D Ovalı, ML Öveçoğlu, I Duman Advanced Powder Technology 26 (4), 1200-1209 , 2015 2015.0 Citations: 43
Development of PLA-PBAT and PLA-PBSA bio-blends: Effects of processing type and PLA crystallinity on morphology and mechanical properties MN H Oguz, C Dogan, D Kara, ZT Ozen, D Ovali AIP Conference Proceedings 2055 (1), 030003 , 2019 2019.0 Citations: 25
Characterization of SiO2-encapsulated WSi2/W5Si3 nanoparticles synthesized by a mechanochemical route D Ovalı, D Ağaoğulları, ML Öveçoğlu Ceramics International 44 (8), 9442-9453 , 2018 2018.0 Citations: 19
Characterization of mechanically alloyed and pressureless sintered Al-7 wt% Si-2 wt% LaB6-2 wt%(MoSi2, WSi2) hybrid composites E Tekoğlu, Y Yürektürk, D Ağaoğulları, D Ovalı, S Mertdinç, ML Öveçoğlu Advanced Powder Technology 30 (11), 2626-2635 , 2019 2019.0 Citations: 15
Room-temperature synthesis of tungsten silicide powders using various initial systems D Ovalı, D Ağaoğulları, ML Öveçoğlu International Journal of Refractory Metals and Hard Materials 82, 58-68 , 2019 2019.0 Citations: 13
Spark plasma sintering of molybdenum silicides synthesized from oxide precursors D Ovalı, M Tarraste, M Kaba, D Ağaoğulları, L Kollo, KG Prashanth, ... Ceramics International 47 (10), 13827-13836 , 2021 2021.0 Citations: 11
Effects of excess reactant amounts on the mechanochemically synthesized molybdenum silicides from MoO3, SiO2 and Mg blends D Ovalı, D Ağaoğulları, ML Öveçoğlu International Journal of Refractory Metals and Hard Materials 65, 19-24 , 2017 2017.0 Citations: 11
Photocatalytic Efficiency of ZnO/TiO 2 Composite Plates in Degradation of RR180 Dye Solutions M Konyar, D Ovali, HC Yatmaz, C Duran, K Öztürk Advances in Science and Technology 65, 244-250 , 2011 2011.0 Citations: 11
Mechanochemical synthesis and characterisation of niobium silicide nanoparticles D Ovalı, D Ağaoğulları, ML Öveçoğlu Ceramics International 45 (8), 10654-10663 , 2019 2019.0 Citations: 10
Effects of oxide particles on the microstructural and mechanical properties of W-Ni-WB composites D Ovalı, Ö Balcı, D Ağaoğulları, ML Öveçoğlu Particulate Science and Technology 38 (3), 347-353 , 2020 2020.0 Citations: 5
Investigation of Mechanochemical Synthesized Tungsten Silicides from WO 3 , SiO 2 and Mg Blends D Ovalı, ML Ovecoglu Solid state phenomena 257, 47-51 , 2017 2017.0 Citations: 5
Polyamide 12/Antimony Trioxide/Sepiolite or Boron Composites: Mechanical Properties and Flame Retardancy A ÖZTÜRK, F SARIBAL, Ş DUMAN, M AKKOYUN, ŞEN İ̇brahim, ... Çukurova Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi 35 (4), 1083-1090 , 2020 2020.0 Citations: 4
Powder Metallurgical Processing of Al–5 wt% Cu Matrix Composites Reinforced with MoSi2 and WSi2 Particulates S Mertdinç‐Ülküseven, D Ovalı‐Döndaş, İ Süzer, M Altıntaş, ... Advanced Engineering Materials, 2400622 , 2024 2024.0 Citations: 2
Effect of tungsten disilicide addition on tungsten boride based composites produced by milling-assisted pressureless sintering D Ovalı, D Ağaoğulları, H Gökçe, ML Öveçoğlu Journal of Boron 3 (1), 42-50 , 2018 2018.0 Citations: 2
Room-temperature mechanochemical synthesis of SiC-based ceramic powders D OVALI-DÖNDAŞ Ceramics International , 2025 2025.0 Citations: 1
Co-synthesis of zirconium boride/silicide/oxide composite powders by magnesiothermic reduction D Ovalı-Döndaş Journal of Boron 7 (4), 552-559 , 2022 2022.0 Citations: 1
TiB2 ve La2O3 Partikül Takviyelerinin Mekanik Alaşımlama ve Aktifleştirilmiş Sinterleme ile Üretilen Volfram Matrisli Kompozitler Üzerindeki Etkisinin İncelenmesi D Ağaoğulları, Ö Balcı, H Gökçe, D Ovalı, ML Öveçoğlu Akademik Platform Mühendislik ve Fen Bilimleri Dergisi 7 (1), 95-105 , 2019 2019.0 Citations: 1
Growth and characterization of carbon nanotubes on FeSi substrates via chemical vapor deposition: influence of synthesis parameters and magnetic properties D Kavrar-Ürk, D Ovalı-Döndaş, E Okumuş, H Ağırcan, MY Seyidov, ... Journal of Materials Science: Materials in Electronics 37 (10), 775 , 2026 2026.0
Exploring Fesi as a Substrate: Catalyst for Tailored Carbon Nanotube Synthesis and Their Magnetic Behaviors D Kavrar Ürk, D Ovalı-Döndaş, E Okumuş, H Ağırcan, MY Seyidov, ... Elsevier BV , 0
