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β-titanium shape memory alloys are used as shape memory-based biomedical applications and superelastic materials because they are made up of non-toxic components. Also, their behaviors are more semilar with that of human bone and dental biological tissues, such as biocompatibility, superior corrosion resistance, low density, and low modulus of elasticity. In the current study, the effect of Ta additive on the physical properties of Ti-Nb alloy has been investigated. Ti-Nb-Ta alloy samples were produced such that the Tantalum (Ta) element was substituted instead of Niobium (Nb), and the induction arc melting was used to melting the mixed powders. To investigate the crystal structure, microstructure, and phase transformation temperatures of all samples, the X-Ray Diffraction (XRD), Scanning Electron Microscopic (SEM), and Diffraction Scanning Calorimetry (DSC) measurements have been used. Both β-rich and α peaks were observed in the XRD and SEM measurements. Also, the DSC results revealed that the Ti-Nb-Ta alloys have only austenite transformation temperatures and their phase austenite phase transformation were decreased by the effect of Ta additive, additionally, the enthalpy change in〖 E〗_3 sample ( Ti_75.5 Nb_22.5 Ta_2 (%at)) has the highest value, while E_4 sample ( Ti_75.5 Nb_21.5 Ta_3 (%at)) has the lowest respective value.

Quantum mechanical methods were used to investigate the corrosion inhibitor activities of tetraline and naphthalene compounds. In this study, some parameters were estimated, including, the energy of the highest occupied molecular orbital (EHOMO), the energy of the lowest occupied molecular orbital (ELUMO), the energy bandgap (ΔE = ELUMO - EHOMO), and the dipole moment (μ). The aforementioned parameters give information about the corrosion efficiency of organic compounds. Furthermore, the density functional theory (DFT) was handled to determine the geometry of the molecules and electronic characteristics of the compounds. B3LYP/6-31G (d, p) was utilized to determine physical parameters such as hardness (ɳ), softness (σ), and electronegativity (χ). We also evaluated quantum chemistry characteristics including the fraction of electrons transported (ΔN) between the iron surface and our title compounds. This study also discusses which parameters have a significant linear relationship with inhibitory performance. The findings suggest that the behavior of organic-based corrosion inhibitors is correlated with the effectiveness of good corrosion inhibitors and the quantum chemical parameters measured from this process. As a result, the behavior of corrosion inhibitors can be determined without the need for an experiment.

Thermal conductivity is an important parameter for semiconductor materials used in the nanoscale applications. In this study, the lattice thermal conductivity (LTC) of magnetite thin films was simulated by Modified Callaway Model. To fit the experimental data, some quantities, such as mean bond length, the lattice constant, and volume per atom were calculated. Also, the model is based on some other quantities, such as gruneisen parameter, electron concentration, and surface roughness that were found through fitting theoretical with experimental LTC. As a result, this model could work comparably well in all sizes, and the relationship between the fitting parameters and the thickness of the magnetite films was estimated.

NiTi-based shape memory alloys (SMAs) have many applications, especially for implantation, however since they are not a passive material so it is important to investigate them from different biocompatible perspectives. In this study, we introduced the important physical characteristics of NiTi alloys, then we explained different biocompatible terminologies, including carcinogenic, genotoxic, cytotoxicity, mutagenic, allergic, and corrosivity. We collected some important previous works that investigated the biocompatibility of NiTi-based SMAs and the different techniques used for improving the alloy and diminishing the hazard due to Ni-leakages.

Phenylalanine (Phe) is one of the amino acids that cannot be produced in the body and must be ingested through diet. Tyrosine (Tyr) is also a non-essential amino acid and can be produced by Phe hydroxylation in the liver when the dietary intake of Tyr is low. Structure analysis is very important to know the correct synthesis and the reactivity of the molecule. In this study, the characterization of Phe and Tyr molecules were investigated using quantum chemical calculations. The molecular geometry for both molecules was determined using density functional theory (B3LYP) by handling the 6-311++G(d,p) basis set. The method of TD-DFT which is based on the B3LYP/6-31++G(d,p) level, was utilized in ethanol solvent to find the electronic absorption spectra. In addition, frontier molecular orbitals, electrostatic potential and molecular charge distributions analysis were carried out by B3LYP/6-311++G(d,p) theory. The energy differences between HOMO and LUMO for Phe were obtained as 0.19851 eV, which have a good argument with the reactivity compared with tyrosine, and energy band gap was 0.20501 eV

Characterization of shape memory alloys (SMAs) is important to determine and improve specific properties for a variety of applications. In this study, an arc-melting device was used to create a high Cu content NiTiCu SMA, which was then aged at 1073, 1123, 1173, and 1223 K. Vickers microhardness, differential scanning calorimetry, optical microscope, and scanning electron microscopy-energy dispersion X-ray spectroscopy (SEM–EDS) instruments were used to investigate the mechanical, thermal, and microstructural properties of the aged alloys. The alloys showed a single step (B2 ↔ B19) phase transformation for the measured range of temperatures. The activation energy decreases as the aging temperature increases up to 1173 K. The crystallite size for the alloys aged at 1073 was around 320 nm, while it increased to about 450 and 550 nm for the alloys aged at 1173 and 1223 K, respectively. It was found that the heat-treated alloys have a larger crystallite sizes compared to equiatomic NiTi SMAs and an as-casted NiTiCu SMA produced in the same condition. Also, the hardness of B19 (matrix) was less than that of the Ti2(Ni, Cu) precipitated phase.

Heusler shape memory alloys are important for many applications due to their typical magnetic and shape memory behaviors. In this study, a Ni50Mn36Sn12Co2 (at.%) alloy was manufactured by arc-melting technique, then the ingot cooled to ambient temperature in the natural atmosphere. Three different temperatures, including 500 °C (773 K), 700 °C (973 K), and 900 °C (1173 K), was selected for aging the samples cut from the main ingot. The impact of aging on the crystalline; microstructure; caloric; and magnetic properties of the alloys were investigated through x-ray diffraction (XRD); scanning electron microscope; differential scanning calorimetric (DSC), differential thermal analysis, and thermal gravimetric (TG); and physical property measuring system was investigated, respectively. The aging in different temperatures led to the shift DSC curve, such that the martensitic phase transformation temperatures of the sample aged at 773 K increased, however, the transformation at 973 and 1173 K decreased compared to the as-casted alloy. The different phase transformation behavior showed that the alloy aged at 773 K has the maximum elastic energy, enthalpy and entropy change compared to the reset of samples, on the other hand, its crystallite sized obtained from XRD analysis comparably diminished. Besides, the TG analysis revealed that the mass gain almost occurs at a temperature above 773 K, therefore the magnetization of the alloys aged at 973 and 1173 K decreased due to a thin oxide layer formed on the surface of the alloys.

The electrical conductivity is an important behavior of shape memory alloys. It is known that such alloys exhibit different electrical characteristics during phase transformation. In this study, Ni((50-x))Mn39Sn(11)Ta(x) (x = 0, 1, 3) was produced by the arc-melting method under atmosphere control. The phase transformation temperature of these samples was determined by DSC (differential scanning calorimetry) and ER (electrical resistivity) methods. It was found that NiMnSn SMA is a high-temperature shape memory alloy, and the addition of Ta significantly decreased phase transformation temperature of NiMnSn-based SMAs. Besides, it was observed that these alloys exhibited higher resistivity in the martensite phase compared to the austenite phase. The XRD and SEM-EDX were utilized to investigate crystal structure and microstructure of the alloys. Orthorhombic martensite (10 M and 4O) phase picks were found in XRD analysis. In the SEM analysis, on the other hand, grain boundaries, martensite plates, and porous were observed in the samples.

Shape memory polymers have attracted extensive attention attributable to their characteristics and abundant applications. In this study, shape memory behavior and characterizations of poly(e-caprolactone) (PCL) blended with poly(vinyl chloride) (PVC) and poly(methylmethacrylate) (PMMA) in different proportions were investigated. Some characteristics of the blended polymers, such as attenuated total reflection (ATR) infrared (IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), SEM, and optical microscopy (OM) were accomplished. Both melting temperature (Tm) and glass transition temperature (Tg) were affected by blending polymers. The Tm was decreased from 57 °C to 51 and 49 °C by adding 30% and 50% of PVC to PCL, respectively; moreover, adding 50% PMMA to PCL reduced the Tm of PCL to 55 °C. The TGA results revealed that the temperatures at which the mass of blended polymers begins to lose sharply depend on the ratio of the constituents. It is found that the PCL has a crystalline structure, while PVC and PMMA have an amorphous structure. Shape recovery was not detected in the PCL:PMMA (1:1) since the PMMA polymer did not dissolve in PCL, and therefore, it prevented the homogeneity of the blend. Besides, a shape memory recovering test was performed for PCL:PVC (7:3), whereby the blend showed an excellent strain recovery.

Coating shape-memory alloys (SMAs) with a ceramic layer is an important way by which metallurgists change some physical properties and improve biocompatibilities of (SMAs) for some medical purposes. The oxidation behaviors of five NiTiCo samples with different compositions were investigated and their influence on the thermal characteristics of phase transformation temperatures was studied. The kinetic oxidation as a function of time was determined by using the results of measurements via a combined method of the thermal gravimetrical (TG) and differential thermal (DT) analysis (TG/DTA), at 1323 K for one hour. The SEM-EDX results showed that an oxidation layer covered the surface of the alloys with ceramic compounds consisting of titanium and oxygen. The phase transformation temperatures were increased with respect to non-oxidized NiTiCo alloys. Likewise, the enthalpy change during the heating process was affected by the oxidation process.

The physical characteristics of a shape memory alloy can be controlled by different production techniques and the rate of constituents’ contribution. In this study, CuAlNiHf shape memory alloys, with three different amounts of Hf, were produced by the induction melting method. Many measurements such as differential scanning calorimetry (DSC), scanning electron microscope, energy dispersive X-ray, and the stress–strain test were carried out. The DSC measurement showed that the austenite transformation temperatures were decreased by doping more amount of hafnium into the alloy. All specimens showed a wide temperature hysteresis, which decreased by increasing Hf content. Also, the elastic modulus was raised by increasing the Hf amount. Although $${\gamma }_{1}^{{\prime}}$$ and $${\beta }_{1}^{{\prime}}$$ are the dominant phases in the CuAlNiHf with low Hf composition, substituting Cu with Hf enhanced the amount $${\beta }_{1}^{{\prime}}$$ -phase compared to $${\gamma }_{1}^{{\prime}}$$ -phase.

Thermal and morphological analysis of shape memory alloys is one of the important branches of research to obtain new characteristics. In this study, low amounts of tantalum were added into CuAlNi alloy. The alloy was produced with the induction melting method. The phase transformation of the alloys was characterized by DSC and electrical resistivity for an equal range of temperatures. The alloys showed high-temperature phase transformations. Although the alpha phase existed in all cases, its peak intensity in the XRD result was significantly decreased by adding Ta. The matrixes showed fine martensite plates with beta(1)', and there were also coarse martensite plates with gamma '. Crystallite sizes and Vickers microhardness of the alloys were decreased with increasing tantalum additive. The Cu84Al12Ni3Ta wt% alloy recorded maximum elastic energy and Gibbs free energy.

In this study, the thermal stability and phase transformation of Ni50-xTi50Snx (x = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 at%) SMAs have been investigated. Some thermal, mechanical, and microstructural characteristics were measured using DSC, Vickers microhardness, XRD, and SEM–EDX devices. Calculations, such as grain size and entropy change, were also performed based on the DSC results. It is found that by increasing the amount of Sn in NiTiSn alloy, fragmentation has occurred in the alloy, which may be due to the high concentration of Sn and Ti in the grooves. Furthermore, the microhardness and grain size are in harmony, i.e., the microhardness of the alloys was influenced by the grain size. Additionally, martensite and austenite peaks were shifted to the lower temperature by increasing the cycling process, while the rate of shifting increased generally by adding more Sn element into the alloy.

The new adsorbent was prepared by mixing cellulose with dicyclohexyl-18- crown-6 via microwave irradiation method and it was used to remove lead ions from aqueous solution. In contrast to the traditional way (in which grafted polymers are produced by using chemical-free radical producers), this method is rapid, reproducible, and gives a high-quality product. Different physicochemical techniques such as FTIR, SEM, and XRD and TGA were used for the characterization of the produced adsorbent. Based on the ANOVA statistical value, the adsorption of Pb

NiTi shape memory alloys (SMAs), as smart materials, are broadly used in medical implants and appliances despite the presence of toxic Ni. In this study, NiTiNb alloys were produced using the substitution of biocompatible Nb instead of Ni. The arc-melting method was utilized to make five SMA samples comprising Ni(29−x)Ti50Nb(21+x) (x = 0, 1, 2, 3, and 4); then, the phase transformation temperatures, microstructures, crystal structures, and chemical compositions were investigated by DSC, optical microscopy, XRD, and EDX measurements, respectively. The DSC results showed that the samples had a wide hysteresis with the B19′↔B2 phase transformation and martensite start temperatures below room temperature, which makes them suitable for superelastic implants. The presence of dissolved Nb in the matrix of the alloys was the main reason for the widening of temperature hysteresis. When the XRD and SEM results were examined, the β-rich, B2, B19′, and Ti2Ni phases were observed in all samples. Additionally, the main constituent in the dendritic microstructures was Nb.

Improving shape memory alloys in term of microstructural analysis is important for some related applications. In this study, three different NiTiHf shape memory alloys were produced from high pure elements and by utilizing arc-melting device. The morphologies of different precipitations and microstructures were analyzed by optical microscope, mapping, and EDX compositional analysis. The DSC measurements showed that the phase transformation temperatures is increased by adding more hafnium instead of nickel content in NiTiHf alloy, however, the enthalpy change for both endo/exothermic process were decreased. Also, XRD analysis has been carried out for all alloys to find different phases, and to obtain grain size as a function of different composition of Ni and Hf elements. The oxidation shows that titanium dioxide (TiO2) is spread out over the surface, but the microstructures are completely different for each case, e.g. needle-like shapes (nanorods) has extended over the surface of Alloy A with 3 at% Hf, but plate-like Ti-rich microstructures is dominated on the surface of Alloy B that has twice as more Hf as Alloy A; on the other hand, Alloy C with 9 at% Hf has some precipitates with TiO phase.

Changing physical property of NiTi shape memory alloy by adding new element and heat treatment technique has become interesting in the last decades. In this study, equiatomic NiTi alloy was doped by 1 and 5 atomic percentages of vanadium element. For each case, heat treatment was accomplished for 873, 973, 1073, and 1173 K, and its effect on phase transformation temperatures was analyzed by differential scanning calorimetry. Crystal structure and chemical compound found in XRD pattern showed the different situation for each case, e.g., TiO2 appeared in heat-treated samples, whereby the intensity of peaks varied by changing the temperature of heat treatment. In NiTi–5V alloy, each enthalpy, entropy, Gibbs free energy, and elastic energy were decreased by increasing heat treatment temperature, while grain size of the alloy extended with respect to non-heat-treated sample. Electrical resistivity of the alloys was measured as a function of temperature, which was increased by increasing vanadium composition and heat treatment temperature.

In this study, CuAl13−xTax (% mass x = 1; 1.5; 2; 2.5) shape-memory alloys were produced through arc-melting method. Phase transformation temperatures were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis. Microstructures were examined with the aid of optical microscopy, scanning electron microscopy–energy-dispersive X-ray (SEM–EDX) and X-ray diffraction (XRD). The ratios of electron per atom (e/a) for CuAl13−xTa1, CuAl13−xTa1.5, CuAl13−xTa2 and CuAl13−xTa2.5 were calculated as 1.52, 1.51, 1.50 and 1.49, respectively. DSC results showed that CuAlTa alloys belong to high-temperature shape-memory alloys. Also, it was identified that these alloys demonstrate $$2{\text{H}}(\upgamma_{1}^{\prime } ) \to {\text{DO}}_{3} (\upbeta_{1} ) \to 18{\text{R}}(\upbeta_{1}^{\prime } )$$ phase transformation. It was observed that both phase transformation temperature and oxidation sensitivity of the samples decreased with the increase in the amount of Ta. In the XRD analysis of CuAlTa HTSMA alloys, some phases were observed, including $$\upgamma^{\prime } ,\;\upbeta^{\prime }$$ Cu9Al4, CuAl and Ta2Al3. These phases were supported by SEM–EDX results. The micro-hardness values of the alloys were increased by increasing Ta content.

In the present work, Ni32-x-Ti-Ta18+x (x = 0, 2, 3, 4, 5, 6, 7, 8) shape memory alloys, produced by arc-melting method. Then, differential scanning calorimetry (DSC), optical microscopy (OM), x-ray diffraction (XRD), and Vickers micro-hardness measurements were carried out to investigate thermodynamic parameters, microstructure, crystal structure, and mechanical properties of the alloys, respectively. The DSC results showed that, as the amount of Ta increased, the phase transformation temperatures of the specimens significantly changed. In addition, increasing of Ta composition raised the mass density and electron participation of NiTi alloy, and thus, the vibrational term of entropy overcomes the electron participation; consequently, the total entropy declined in the alloys. It is found that OM images possess a dendritic microstructure, where by increasing the amount of Ta, the dendrites length increase while random orientations decrease. Moreover, XRD patterns exhibited the existence of each austenite phase (B2), martensite phase (B19ʹ), and β-Ta riched phase in all samples.

Like alloys in metallurgy, polymers are blended to obtain new characteristics, which is important to extend their application area. In this study, three different compositions of azide-functionalized poly(vinyl chloride)-PVC-N3 and poly(e-caprolactone)-PCL were blended. Physical properties, such as mechanical and thermal behavior of the blends, were investigated through the tensile test, DSC, and TGA. Also, a blended polymer with equal participation of each constituent was trained to determine the shape memory behavior of the sample. The results showed that PVC-N3 and PCL were completely miscible; therefore, all physical properties are somewhere between the pure polymers. The blend with only 50% PCL, as an example, still kept its shape memory behavior; additionally, the blended polymers partially achieved crystalline behavior by adding PCL to the PVC-N3. The tensile test also showed that the modulus of toughness and other mechanical behavior depends on the compositional ratio of the polymers. Consequently, the miscibility of the PCL and PVC-N3 enhances the physical properties of both polymers as a function of composition.

Polyvinyl chloride (PVC) is one of the popular materials that extensively used in different areas, so scientists are trying to investigate its characteristics in different formats, such as blends and composites, to improve its properties. Due to the distinctive nano particles’ properties, polymer-based nanocomposites can offer new characteristics to pure polymers and can widen their applications in different areas. In this study, we added different compositions of silicon carbide (SiC) to PVC to investigate its molecular, thermal, and microstructural properties. Attenuated total reflection- infrared (ATR-IR), thermogravimetry (TG), differential scanning calorimetry (DSC), and optical microscopy (OM) were utilized to study molecular bond structure, thermal degradation, caloric properties, and surface morphology of the pure PVC and its composites. The first derivative of TG results showed that the temperature of the maximum thermal degradation of the PVC increased with increasing SiC nanoparticle ratio. Also, it is found that the PVC/12 mol% SiC started thermal degradation at comparably low temperature, however, the amount of residue of the composites is more than the pure PVC. Additionally, SiC nanoparticles caused the melting temperature of the composites to slightly shifts to a lower temperature compared to the PVC. It was observed that silicon carbide diminished the smoothness of the surface by increasing its fraction in the composite.

The developed NiTi-based shape memory alloys are the most widely used materials in commercial applications due to shape memory effect and superelasticity. In this study, it is aimed to investigate the thermal, microstructural, and corrosion behavior of NiTiNb SMA by alloying with different composition of vanadium. The alloys with nominal composition Ni27Ti50Nb23-xVx (x = 1, 2, 5) were manufactured by the arc-melting device under an argon gas atmosphere. The DSC measurements showed that the alloys are low-temperature shape memory alloys and the changes in the composition have not made a significant effect on the phase transformation temperatures. According to thermodynamics parameters, such as enthalpy and entropy changes, it is found that the alloy with 2 (at.%) of vanadium has more stability compared with the other SMAs. The microstructural analysis reveals that the Ni27Ti50Nb21V2 (at.%) alloy has a different dendritic microstructure, whereby, the mapping shows that the dendritic of the alloy almost consists of Nb, while the other alloys Ti are the host element in the dendritic microstructure. It is realized that the manufactured alloys have less biocompatibility since they have shown a high corrosion rate compared to equiatomic NiTi SMAs.

The heat treatment techniques are significant methods for improving metals and alloys. Particularly, it is important to control transformation temperature and improve mechanical and physical properties of materials. There are two important parameters that can be controlled, which are temperature and time of aging. In this study, a quaternary Cu-79-Al-12-Ni-4-Nb-5 (wt%) alloy was produced using arc melting under an atmosphere control. The alloy was aged isothermally at 1073 K for 1, 2, 3, 6, 12, and 24 h. The map of constituents showed that neither Cu contributed in Nb-rich phases nor Nb dissolved in the matrix. The martensitic phase transformation for as-casted and aged specimens was carried out using a DSC device. The phase transformation was generally shifted to the higher temperature by increasing the time of aging, but the alloy lost its shape memory feature when it was aged for 24 h. XRD and optical microscopy were utilized to investigate characterizations of the alloy. Additionally, the aging introduced multiphases in the alloys and the intensity of XRD peaks was increased by increasing the time of aging up to 3 h.

A quaternary Cu80Al13Ni3Hf4 (wt%) shape memory alloy has been produced from high pure metallic powder through arc-melting method. Then homogenization been performed at 1173 K for 24 h and followed by a rapid cooling to salt-iced water. As a technique, one hour heat treatment at 773 K, 873 K, 973 K, 1073 K, and 1173 K, has been done to investigate some physical and structural properties. Some relevant measurements by using DSC, XRD, EDX-SEM, and Vickers hardness devices has been accomplished. While both DSC and XRD results showed that in room temperature all specimens were in austenite phase, but increasing the temperature of heat treatment make changes in the amount of precipitations presented in SEM micro-images, and hence led to a decrease in microhardness values. The sample with 1173 K heat treatment was the more stable phase compared to the other specimens, because a minimum values was obtained in calculation of Gibbs free energy and entropy.

Lattice thermal conductivity (LTC) of Si bulk and nanowires (NWs) with diameter 22, 37, 50, 56, 98 and 115 nm was investigated in the temperature range 3–300 K using a modified Callaway model that contains both longitudinal and transverse modes. Using proper equations, mean bond length, lattice parameter, unit cell volume, mass density, melting temperature, longitudinal and transverse Debye temperature and group velocity for all transverse and longitudinal modes were calculated for each NW diameter mentioned. Surface roughness, Gruneisen parameter and impurity were used as adjustable parameters to fit theoretical results with experimental curves. In addition, values of electron concentration and dislocation density were determined. There are some phonon scattering mechanisms assumed, which are Umklapp and normal processes, imperfections, phonon confinement, NW boundaries, electrons scattering and dislocation. Dislocation density less than 10 $$^{{14}}$$ m $$^{{-2}}$$ for NWs and 10 $$^{{12}}$$ m $$^{{-2}}$$ for bulk has no effect on LTC. Also, electron concentration less than 10 $$^{{22}}$$ m $$^{{-3}}$$ for NWs and 10 $$^{{16}}$$ m $$^{{-3}}$$ for the bulk has no effect. On increasing dislocation density and electron concentration, LTC comparably decreases.

$$\hbox {Ni}_{ 50-x}\hbox {Ti}_{50}\hbox {Cu}_x$$ (at.%) $$x=14, 17, 20)$$ shape memory alloys were produced using the arc-melting technique. The replacing Cu element into Ti-rich NiTi alloy has been investigated through characterization techniques, including differential scanning calorimetry (DSC), X-ray diffraction (XRD), optical and SEM microscopy. Additionally, various phases and precipitations were determined using EDS measurement. The manufactured alloys showed a single-step austenite $$\leftrightarrow $$ martensite phase transformation (B2 $$\leftrightarrow $$$$\hbox {B19}^{\prime }$$ ). The DSC results showed that the samples have comparable high-temperature hysteresis in the range of about (30–50 K). The main detected XRD peaks are the monoclinic martensite phase with cubic austenite phases, which their intensities were decreased by increasing copper addition into the alloy. The microhardness results revealed that the second phase of the alloys has higher hardness compared to the matrix phase. It was concluded that NiTiCu can be used in low-temperature shape memory alloys as they illustrate transformation temperature below $$100\,^{\circ }\hbox {C}$$

Mathematical modeling has been extended to simulate some physical systems to calculate some parameters that may need a sophisticated cost or may have some obstacles to be measured directly with an experimental method. In this study, the Modified Callaway Model has been used to calculate size dependence lattice thermal conductivity (LTC), and the influence of carrier concentration for bulk Si and its nanowires (NWs) with diameters of 22, 37, 56, and 115 nm has been investigated. Calculations were performed from 3K to 1600K for all cases. The effects of carrier concentration on LTC has found to begin from (1016 cm-1) for the bulk state and that increased to (1024 cm-1) for the NW with a diameter of 22 nm. The temperature that the maximum effect of carrier concentration can occur, has found to be at (10 K) for the bulk, and that increased to (340 K) for the (22 nm) Si NW.

Non-isothermal oxidation behavior of Ni50Ti49.6V0.4 (at.%) and Ni50Ti46V4 (at.%) polycrystalline alloys was investigated through thermogravimetric analysis. Differential scanning calorimetry and scanning electron microscope were used to study the role of oxidations on the transformation temperatures and surface characteristics, respectively. It was revealed that the oxidation response of the alloys is very sensitive to the vanadium content and the oxidation temperature. The oxidation constant was linearly proportional to oxidation temperatures ranging between 850 and 1150 °C. It was found that the activation energies for oxidation decreased from 207.81 $$(\mp $$ 5.6) to 192.8 $$(\mp $$ 3.8) kJ/mol, while the vanadium content increased from 0.4 to 4%. The effects of chemical composition and temperature on the oxidation behavior were discussed. The surface of both alloys was covered by a titanium dioxide and nickel-enriched layer through the isothermal oxidation process. The grain size of the alloys was affected by the increasing oxidation temperature.

Akilli malzemeler, ileri malzemeler grubunda yeralan, bir malzeme grubudur. Bu malzeme gruplari, cevresi ile kendi kendine uyum icindedir ve bazi fiziksel (basinc, sicaklik, nem, isik, elektrik alan, manyetik alan), kimyasal (pH, CO2 vb.) veya biyolojik uyarilara verdikleri tepkilere gore siniflandirilirlar. Akilli malzemeler, sogurulan enerjiyi, karakteristik ozelliklerini degistirmek icin donustururler. Akilli malzemeler, aktuator veya sensor seklindeki ticari uygulamalari nedeniyle yuksek oranda dikkat ceker. Bu calisma, farkli turdeki akilli malzemelerin spesifik ozellikleriyle birlikte ozel bir incelemesini ve akilli malzemelerin ozelliklerini iyilestiren bazi ilgili arastirmalari gostermektedir. Ayrica, akilli malzemelerin uygulamalari, tibbi implantasyon, atiklari azaltma ve nano muhendislik sistemleri gibi farkli uygulama alanlarina gore kategorilere ayrilmaktadir

The development of NiTi-based shape memory alloys (SMAs) for some medical applications has been limited by releasing Ni element into the organic tissue. In this study, Ni[Formula: see text]Ti[Formula: see text]Sn3-wire (at.%) SMA was produced using the arc-melting technique, and the alloy was subjected to non-isothermal processes. Some characteristics of the alloys, such as oxidation behavior, corrosivity, and in vitro study in simulated body fluid and physiological solution at body temperature, were investigated. The corrosion rate of the as-casted alloy was lower than the equiatomic-NiTi alloy found in the literature. The estimated ICP-MS results showed that the release of alloying constituents into the solutions is in accordance with the standards.

It is aimed to investigate the coating of AISI316 stainless steel with NiCrBSi/WC at different ratios using TIG method. In this study, the Ni-based WC-reinforced MMC layer was manufactured by the TIG composite coating method, and then the microstructure of the coating layer was examined. Microstructure and phase components of the composite coatings were characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. A metallurgic bound was found between the coating layer and the substrate through the TIG coating process. WC was re-solidified in the matrix by dissolving with high input energy. Several phases were found, including Ni-rich ([Formula: see text]-Ni) primary dendritic phase, Ni-Ni3B, and Ni3Si eutectic structure, Cr7C3, Cr2B3, Cr3Ni2, Ni2W4C, and Ni[Formula: see text]W3 phases in dendritic structures. The presence of carbides in the structure had affected the hardness of the coating. The maximum hardness value was found to be 469.5 HV and the hardness of the coating layers was increased at least 2.5 times compared to that of the substrate material.

In this paper, Cu85Al12Cr3 and Cu83Al12Cr3Ni2 (wt. %) high temperature shape memory alloys (HTSMA) were fabricated from highly pure powder elements by using an arc melter. After production, some pieces of alloys were subjected to heat treatment at 1073K for one hour. Then, Differential Scanning Calorimeter (DSC), Optical Microscopy (OM), X-Ray Diffraction (XRD), Vickers microhardness, and Scanning Electron Microscopy (SEM) analyses were carried out to investigate thermodynamic parameters, microstructure, crystal structure, mechanic properties, and to determine precipitation types in non-heat-treated and heat-treated alloys, respectively. According to the results of DSC measurements, both alloys showed a high temperature shape memory effect; also, the phase transformation temperatures of the alloys were affected by the heat treatment. The analysis of XRD patterns showed two different predominant microstructures in both alloys, i.e. $\gamma^{\prime}_{1}$ and $\beta^{\prime}_{1}$ phases. Moreover, microstructural results showed the influence of Ni additive in decreasing the size of the grains and the number of the precipitates. In addition, micro-hardness, as a mechanic property, decreased through adding Ni to the CuAlCr alloy.