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Graeme Hansford
A conceptual design for a handheld X-ray diffraction (HHXRD) instrument is proposed. Central to the design is the application of energy-dispersive XRD (EDXRD) in a back-reflection geometry. This technique brings unique advantages which enable a handheld instrument format, most notably, insensitivity to sample morphology and to the precise sample position relative to the instrument. For fine-grained samples, including many geological specimens and the majority of common alloys, these characteristics negate sample preparation requirements...
December 1, 2018: Journal of Applied Crystallography
Nikita Yurchenko, Evgeniya Panina, Sergey Zherebtsov, Gennady Salishchev, Nikita Stepanov
Oxidation behavior of a refractory AlNbTiVZr0.25 high-entropy alloy at 600⁻900 °C was investigated. At 600⁻700 °C, two-stage oxidation kinetics was found: Nearly parabolic oxidation (n = 0.46⁻0.48) at the first stage, transitioned to breakaway oxidation (n = 0.75⁻0.72) at the second stage. At 800 °C, the oxidation kinetics was nearly linear (n = 0.92) throughout the entire duration of testing. At 900 °C, the specimen disintegrated after 50 h of testing. The specific mass gains were estimated to be 7...
December 12, 2018: Materials
Abhilash Edacherian, Ali Algahtani, Vineet Tirth
Several challenges stand in the way of the production of metal matrix composites (MMCs) such as higher processing temperatures, particulate mixing, particulate⁻matrix interface bonding issues, and the ability to process into desired geometrical shapes. Although there are many studies showing composites with single particulate reinforcements, studies on composites with multiple reinforcing agents (hybrid composites) are found to be limited. Development of a hybrid particulate composite with optimized mechanical and tribological properties is very significant to suit modern engineering applications...
December 12, 2018: Materials
Gang Song, Taotao Li, Jingwei Yu, Liming Liu
The challenge of joining immiscible Mg/Steel dissimilar metals lies in the absence of an Fe-Mg intermetallic or Fe-Mg solid solution in an Mg-Fe system, and differences in their physical and chemical properties. Promoting interfacial reaction and regulating the composition of interface layer are beneficial for the formation of an Mg/steel interface layer and to obtain an effective Mg/steel joint. This research work focusses on the bonding of immiscible Mg/steel dissimilar metals: First, an Mg/steel interface layer was designed by controlling the composition of added alloy elements and trace elements in the base metal...
December 11, 2018: Materials
Wang Jianwei, Xiao Wei, Zhang Chuan, Sun Lu, Huang Guojie, Shi Jingmin, Wang Ligen
A high-throughput method was employed to effectively obtain the cross-scale relationship of elastic copper alloys. Firstly, a Cu⁻Ni⁻Ti⁻Cu25Al⁻Cu35Sn diffusion multiple was prepared and heat-treated under a specified condition to form a series of diffusion layers with the concentration gradient at the multielement metal interface. Then, the compositions, elastic moduli, and hardness of the Cu⁻Ni⁻Al and Cu⁻Ti⁻Al ternary copper alloys were tested. Meanwhile, the solid phase sequences in the diffusion zones were predicted by the CALPHAD (CALculation of PHAse Diagram) method...
December 11, 2018: Materials
Aleksandra Radtke, Marlena Grodzicka, Michalina Ehlert, Tadeusz M Muzioł, Marek Szkodo, Michał Bartmański, Piotr Piszczek
Dispersed silver nanoparticles (AgNPs) on the surface of titanium alloy (Ti6Al4V) and titanium alloy modified by titania nanotube layer (Ti6Al4V/TNT) substrates were produced by the chemical vapor deposition method (CVD) using a novel precursor of the formula [Ag₅(O₂CC₂F₅)₅(H₂O)₃]. The structure and volatile properties of this compound were determined using single crystal X-ray diffractometry, variable temperature IR spectrophotometry (VT IR), and electron inducted mass spectrometry (EI MS). The morphology and the structure of the produced Ti6Al4V/AgNPs and Ti6Al4V/TNT/AgNPs composites were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM)...
December 9, 2018: International Journal of Molecular Sciences
Jin Zou, De-Ping Lu, Ke-Ming Liu, Qing-Feng Fu
An alternating magnetic field (AMF)/Ag multi-alloying combined process was applied to the solidification of Cu⁻14Fe alloy to study its effects on the microstructure and properties of the resulting samples. The applied AMF and Ag multi-alloying had positive effects on the refinement of the primary Fe phase and precipitation of Fe solute atoms, respectively. These results indicated that the combined AMF/Ag multi-alloying process was effective to improve the distribution of the primary Fe phase and reduce the Fe content of the Cu matrix, which increased the conductivity of the alloy...
December 9, 2018: Materials
Yin-Yu Chang, Jia-Hao Zhang, Heng-Li Huang
Titanium dioxide and vanadium oxides have been applied extensively in industrial and medical fields. The objective of this study was to develop various composite structures of titanium and vanadium oxide (Ti-V-O) coatings on pure titanium through high-temperature annealing and laser texturing oxidation, separately; additionally, surface morphologies, tribological and hydrophilic properties, and antibacterial and biocompatibility abilities of these Ti-V-O coatings were evaluated. TiV alloy thin films were deposited on pure titanium and then annealed to form Ti-V-O coatings through thermal oxidation and laser texturing oxidation...
December 8, 2018: Materials
Wanwu Ding, Taili Chen, Xiaoyan Zhao, Chen Xu, Xingchang Tang, Jisen Qiao
The effects of CeO₂ on the microstructure and synthesis mechanism of Al-Ti-C alloy were investigated by quenching experiment method, while using Al powder, Ti powder, graphite powder, and CeO₂ powder as main raw materials. The results showed that the addition of CeO₂ was favorable for promoting the formation of TiC particles in Al-Ti-C systems. With CeO₂ contents increasing, the distribution of TiC particles were more homogeneous, and the rare earth phase Ti₂Al20 Ce was formed. CeO₂ had little effect on the synthesis of Al₃Ti particles in Al-Ti-C systems, but had a significant effect on the synthesis of TiC particles...
December 10, 2018: Materials
Yongjian Zhang, Weijun Hui, Xiaoli Zhao, Cunyu Wang, Han Dong
The effects of hot stamping (HS) and tempering on the hydrogen embrittlement (HE) behavior of a low-carbon boron-alloyed steel were studied by using slow strain rate tensile (SSRT) tests on notched sheet specimens. It was found that an additional significant hydrogen desorption peak at round 65⁻80 °C appeared after hydrogen-charging, the corresponding hydrogen concentration ( C Hr ) of the HS specimen was higher than that of the directed quenched (DQ) specimen, and subsequent low-temperature tempering gave rise to a decrease of C Hr ...
December 10, 2018: Materials
Gonçalo Pina Cipriano, Lucian A Blaga, Jorge F Dos Santos, Pedro Vilaça, Sergio T Amancio-Filho
The present work investigates the correlation between energy efficiency and global mechanical performance of hybrid aluminum alloy AA2024 (polyetherimide joints), produced by force-controlled friction riveting. The combinations of parameters followed a central composite design of experiments. Joint formation was correlated with mechanical performance via a volumetric ratio (0.28⁻0.66 a.u.), with a proposed improvement yielding higher accuracy. Global mechanical performance and ultimate tensile force varied considerably across the range of parameters (1096⁻9668 N)...
December 7, 2018: Materials
Fumiki Takahashi, Masaru Kobayashi, Atsushi Kobayashi, Kanya Kobayashi, Hideki Asamura
Background: A simple, sensitive, and rapid extraction method based on high-frequency (H-F) heating was developed for drug analysis in human nails. Methods: A human nail was placed in a glass tube with an extraction solvent (methanol and 0.1% formic acid; 7:3, v / v ), and a ferromagnetic alloy (pyrofoil) was wrapped in a spiral around the glass tube. Then, the glass tube was placed in a Curie point pyrolyzer, and a H-F alternating voltage (600 kHz) was applied. The sample and extraction solvent were heated at the Curie temperature for 3 min...
December 7, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
S Chaudhuri, P A Bhobe, Arpan Bhattacharya, A K Nigam
With an aim to control the anti-site disorder between Fe and Ti atoms in the full Heusler alloy, Fe[Formula: see text]TiSn, we substitute a small percentage of Ti at Fe site to form the Fe[Formula: see text]Ti[Formula: see text]Sn ([Formula: see text]) series. Using the incident x-rays tuned to the Fe K-edge absorption energy, we record the high resolution synchrotron x-ray diffraction profiles and unambiguously show the reduction in anti-site disorder. In particular, the Fe-Ti anti-site disorder decreases up to an excess Ti content of 0...
December 13, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Bingchao Qin, Dongyang Wang, Wenke He, Yang Zhang, Haijun Wu, Stephen J Pennycook, Li-Dong Zhao
The simple binary compound SnSe has been reported as a robust thermoelectric material for energy conversion by showing strong anharmonicity and multiple electronic valence bands. Herein, we report a record high average ZT value > 1.6 at 300-793 K with maximum ZT values ranging from 0.8 at 300 K to 2.1 at 793 K in p-type SnSe crystals. This remarkable thermoelectric performance arises from the enhanced power factor and lowered lattice thermal conductivity through crystal structure modification via Te alloying...
December 13, 2018: Journal of the American Chemical Society
Yuzhen Zou, Gang Wang, Yiming Xu, Yuehong Bai
The aim of the present study was to investigate the proliferation of skeletal muscle satellite cells (MSCs) under different amounts of microwave irradiation in fractures with titanium alloy internal fixation. A total of 45 male New Zealand adult white rabbits were used to establish a femoral shaft fracture and titanium alloy internal fixation model. The rabbits were randomly divided into the control group (group A) and the experimental groups (groups B and C). For 15 days, groups B and C were exposed to microwave treatment (25 or 50 W, respectively) for 10 min per day...
December 2018: Experimental and Therapeutic Medicine
Feng Zhang, Huairuo Zhang, Sergiy Krylyuk, Cory A Milligan, Yuqi Zhu, Dmitry Y Zemlyanov, Leonid A Bendersky, Benjamin P Burton, Albert V Davydov, Joerg Appenzeller
Transition metal dichalcogenides have attracted attention as potential building blocks for various electronic applications due to their atomically thin nature and polymorphism. Here, we report an electric-field-induced structural transition from a 2H semiconducting to a distorted transient structure (2Hd ) and orthorhombic Td conducting phase in vertical 2H-MoTe2 - and Mo1-x Wx Te2 -based resistive random access memory (RRAM) devices. RRAM programming voltages are tunable by the transition metal dichalcogenide thickness and show a distinctive trend of requiring lower electric fields for Mo1-x Wx Te2 alloys versus MoTe2 compounds...
January 2019: Nature Materials
H Chouirfa, H Bouloussa, V Migonney, C Falentin-Daudré
Implanted biomaterials play a key role in the current success of orthopedic and dental procedures. Pure titanium and its alloys are the most commonly used materials for permanent implants in contact with bone. However, implant-related infections remain among the leading reasons for failure. The most critical pathogenic event in the development of infection on biomaterials is biofilm formation, which starts immediately after bacterial adhesion. In the last decade, numerous studies reported the ability of titanium surface modifications and coatings to minimize bacterial adhesion, inhibit biofilm formation and provide effective bacterial killing to protect implanted biomaterials...
January 1, 2019: Acta Biomaterialia
Ronny Grunert, Sandra Klietz, Paul A Gardner, Juan C Fernandez-Miranda, Carl H Snyderman
In minimally invasive surgeries, it can be difficult to reach desired anatomic areas with rigid instruments, especially when obstacles are present in the surgical corridor (e.g., during transnasal pituitary surgery). We developed a new kind of suction device constructed of the shape-memory alloy Nitinol (nickel titanium), which is adaptable to a patient's specific anatomy. Use of this device minimizes surgical risks by allowing physicians to use an endonasal transsphenoid approach. The suction device, which is equipped with a cannula made of the shape-memory alloy, was planned and manufactured with three different handpiece designs...
December 2018: Ear, Nose, & Throat Journal
Young-Hoo Kim, Jang-Won Park, Jun-Shik Kim
No study has compared the prevalence of fretting and corrosion at the trunnion of cobalt-chrome (Co-Cr) and zirconia ceramic heads in the same patients. The authors sought to compare the prevalence of fretting and corrosion at the trunnion after total hip arthroplasty with a 32-mm Co-Cr or a 32-mm zirconia ceramic head-on-polyethylene bearing. Isolated revision of the ace-tabular components was performed in 78 patients (156 hips) for polyethylene wear and osteolysis of the acetabulum. Seventy-eight Co-Cr head-titanium alloy stem pairs were compared with 78 zirconia ceramic head-titanium alloy stem pairs in the same patients...
December 11, 2018: Orthopedics
Georgios Giannakakis, Maria Flytzani-Stephanopoulos, E Charles H Sykes
Heterogeneous catalysts are workhorses in the industrial production of most commodity and specialty chemicals, and have widespread energy and environmental applications, with the annual market value of the catalysts themselves reaching almost $20 billion in 2018. These catalysts are complex, comprising multicomponent materials and multiple structures, making their rational design challenging, if not impossible. Furthermore, typical active metals like Pt, Pd, and Rh are expensive and can be susceptible to poisoning by CO, coking, and they are not always 100% selective...
December 12, 2018: Accounts of Chemical Research
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