Çelik, Ertuğrul

This study investigates the effect of boron addition on the microstructural, mechanical, and corrosion properties of NiCrBSi alloy fabricated by the spark plasma sintering (SPS) method. Boron was added at levels of 1.5, 3, and 4.5 wt.%, and sintering was conducted at 950 °C for 5 min. Microstructural characterization was carried out using SEM–EDS and XRD analyses, hardness was measured by the Vickers method, and densities were determined according to Archimedes’ principle. The transverse rupture strength (TRS) was obtained by three-point bending tests, while wear performance was evaluated in a reciprocating wear mode. Corrosion behavior was examined through potentiodynamic polarization in a 0.1 M HCl solution. Increasing boron content promoted the formation of nickel and chromium boride phases, enhancing hardness (up to 675 HV0.5) and wear resistance but reducing TRS values due to brittle intermetallic formation. Furthermore, corrosion protection efficiency improved, reaching about 65.9% at 4.5 wt.% B addition.

İncele

Karaduman, Oktay; Boyrazli, Mustafa; Canbay, Canan Aksu; Özkul, İskender; Çelik, Emrah; Başbağ, Güneş

For the first time, CuAlVMg high-temperature shape memory alloy (HTSMA) with unprecedented alloy composition and with extended solubility of vanadium element was fabricated as-cast ingot by arc melting method, then homogenization of the alloy in high β-phase temperature region and quenching in iced-brine water were performed, respectively. The characteristic forward martensite to austenite martensitic transformation (MT) temperatures were detected at around 390 °C, which put the novel alloy in the category of HTSMAs. The thermal response of the alloy at high-temperatures was observed by DTA test as coherent with usual Cu-based HTSMAs. The residual sub-eutectoid precipitations emerging at around 500 °C hindered the direct martensitic transformation. The martensite structure of the alloy was revealed by XRD, SEM and optical microscopy tests.

İncele

Simsek, Tuncay; Kurtulus, Altug; Avar, Baris; Güler, Seval Hale; Dag, İlker Emin; Chattopadhyay, Arun K.

This study focuses on synthesizing and characterizing mechanically alloyed refractory high entropy alloys (RHEA) containing TiMoNb, Cr, W, and Cr + W. Analytical techniques including XRD, SEM, EDX, DTA, and TGA were employed to explore the influence of Cr and W on the alloys' structure, morphology, and thermal stability towards oxidation. XRD analysis confirmed the formation of a single-phase bcc solid solution in TiMoNbCr, TiMoNbW, and TiMoNbCrW alloys. Crystallite size decreased as milling progressed, yielding average sizes of approximately 7.2 nm, 7.4 nm, and 9.7 nm, with lattice strains of 1.143%, 1.148%, and 1.15%, respectively. Both experimental and calculated values of lattice parameters converged to around 3.1685 ± 0.002 and 3.1791 ± 0.010 Å for all three alloys. The synergy of Cr and W in TiMoNb was observed for the first time, impacting dislocation density, hardness, and oxidation stability. TiMoNbCrW exhibited reduced dislocation density and the highest hardness (502 HV). TGA indicated enhanced oxidation resistance up to 400 °C for TiMoNbCrW compared to the most vulnerable TiMoNbCr alloy.

AtıfScopus2·OpenAlex2

İncele

Say, Yakup; Kanca, Muhammed Sait; Kök, Mediha

NiTinol alloy has recently been in high demand in biomaterials applications due to its excellent superelasticity and shape memory properties. This demand has increased the studies on improving the negative properties of the NiTinol alloy, even if it is less. In this study, it was aimed to coat the nickel element in the NiTi alloy with biocompatible elements in order to prevent it from secreting its toxic effect after its implantation into the body. In accordance with this purpose, NiTi shape memory alloys were coated with silver and copper element by using thermal evaporation system, and the surface morphology of the alloys after coating was investigated by SEM–EDX (Scanning Electron microscope), and AFM (Atomic force Microscope). After the measurements, it was observed that the coating was successful and homogeneously distributed on the entire surface of the alloy. In addition, an important and positive result was that, the roughness value of the NiTi alloy was decreased with the coating. The change in the crystal structure of the uncoated and coated NiTi alloy was evaluated using an X-ray device, and it was observed that the silver and copper element peaks were formed along with the B2 phase, which is the main phase of the NiTi alloy. In order to examine the effect of coating on the biocompatibility of NiTi alloy, electrochemical test was performed by rapid measurement method in simulated body fluid and corrosion behavior was investigated. According to these experiments, it was concluded that silver plating is more successful in term of biocompatibility than copper coating.

AtıfScopus4·WoS3·OpenAlex4

İncele

Cihangir, Salih

Copper is the forefront of the fundamental metals used in various industries. It is utilized as bulk or electrodeposited on PCBs or interconnects. However, poor corrosion resistance and hardness reduce copper performance and limit its applicability in the fields that require mechanical strength, such as probing applications. Facile electrochemical deposition of Cu(Ag) films was examined in a deep eutectic solvent known for its green nature. SEM–EDS technique was applied for morphostructural and crsytal plane analysis. XRD analysis revealed Cu3.96Ag0.04 phase, and 2% Ag was identified in the Cu(Ag) film in EDS. Four-prope point resistivity analysis was performed via galvano-impedance spectroscopy. Obtained resistivity value of 5 µm thick Cu(Ag) coating was lower than the compliance limit of International Technology Roadmap for Semiconductors. Corrosion analysis was carried out via electrochemical impedance spectroscopy technique, and Cu(Ag) films demonstrated better resistance. Hardness tests also revealed that Cu(Ag) was approximately two times harder than Cu. Graphical Abstract: [Figure not available: see fulltext.]

AtıfScopus6·WoS6·OpenAlex6

İncele