Plastic behaviours during tempering by crystal plasticity analyses using fast Fourier transform

ABSTRACT

Heat treatment, such as quenching and carburising, often involves volume change caused by phenomena such as thermal expansion, phase transformation, and carbide precipitation during tempering. During the tempering process, an external force induces additional plastic deformation. The authors termed this phenomenon ‘tempering plasticity’. In this study, we performed crystal plasticity analysis using fast Fourier transform considering the volume change in carbides to assess the mechanism of tempering plasticity. As a result, tempering plastic strain occurred as the volume fraction of carbide increased, and the tempering plastic phenomenon could be reproduced based on the transformation model proposed by Greenwood–Johnson. The result supports the idea that the volume change accompanied by carbide precipitation is an important mechanism that invokes tempering plasticity.     

Manufacture of organic transistors on large‐area flexible substrate using direct imaging exposure system by wet process suitable for roll‐to‐roll production

Organic thin‐film transistors (OTFTs) can be fabricated via a wet process and have exceptionally high flexibility. Therefore, production using the roll‐to‐roll (RtoR) method is expected. We succeeded in developing a new OTFT wet fabrication process adaptable to the RtoR process. Utilizing the electroless plating method for wiring formation, all materials can be formed in a wet process and can be patterned using the photolithography process. In addition, we succeeded in fabricating OTFT on an A4‐type flexible substrate using RtoR direct imaging exposure system.     

An International Research Comparative Study of the Degree of Cooperation between disciplines within mathematics and mathematical sciences: proposal and application of new indices for identifying the specialized field of researchers

Behaviormetrika - Based on 10 years of data on academic papers from 2005 to 2014 available on the “Web of Science”, we conducted an in-depth review and analysis of...     

Pulmonary actinomycosis with "balls-in-a hole" appearance diagnosed by examination of bronchial lavage fluid

A 49-year-old man was referred to our hospital because of abnormal chest X-ray findings. Chest X-ray films showed infiltrative opacities in the right lung, and histological findings of a transbronchial biopsy specimen showed non-specific inflammation. The patient was treated with Ofloxacin for one month. After the treatment, chest X-ray films showed that the infiltrative opacities in the right upper lobe had decreased, but that opacities in the right lower lobe had increased, with an air meniscus sign. A chest computed tomography scan at the same time revealed that the remaining opacities contained multiple mass-like lesions within a cavity in the right S6, appearing as "balls in a hole". One year after the first visit, the patient visited the hospital again because of cough and sputum. A chest X-ray film showed that the size of the cavity in the right lower lobe had increased. The histological findings from a fresh transbronchial biopsy specimen revealed a non-specific inflammation again; however, black clots obtained from bronchial lavage fluid after biopsy were histologically identified as sulfur granules, a classic pathological indication of actinomycosis. This confirmed the diagnosis of pulmonary actinomycosis. The patient was treated with penicillin, and the opacities in the right lower lobe subsided.     

4032 ppi High‐resolution OLED microdisplay

A 0.5‐inch Ultra Extended Graphics Array (UXGA) organic light‐emitting diodes microdisplay has been developed with 6.3 μm pixel pitch. Not only 4032 ppi high resolution but high frame rate, low power consumption, wide viewing angle, and high luminance have been achieved. This newly developed organic light‐emitting diodes microdisplay is suitable for Near‐to‐Eye display applications, especially electronic viewfinders.     

Fabrication and flow-sensor application of flexible thermal MEMS device based on Cu on polyimide substrate

A Cu on polyimide (COP) substrate was proposed as a MEMS material, and the fabrication process for a flexible thermal MEMS sensor was developed. The COP substrate application to MEMS devices has the advantage that typical MEMS structures fabricated in a SOI wafer in the past—such as a diaphragm, a beam, a heater formed on a diaphragm—can also be easily produced in the COP substrate in the flexible fashion. These structures can be used as the sensing element in various physical sensors, such as flow, acceleration, and shear stress sensors. A flexible thermal MEMS sensor was produced by using a lift-off process and sacrificial etching of a copper layer on the COP substrate. A metal film working as a flow sensing element was formed on a thin polyimide membrane produced by the sacrificial etching. The fabricated flexible thermal MEMS sensor was used as a flow sensor, and its characteristics were evaluated. The obtained sensor output versus the flow rate curve closely matched the approximate curve derived using King’s law. The rising and falling response times obtained were 0.50 and 0.67 s, respectively.

     

An approach to the deep hydrodesulfurization of light cycle oil

Deep HDS of LCO to be <10 ppm was achieved by fractionating HDS. An LCO fraction having boiling point lower than 340 °C was easily hydrodesulfurized to be <10 ppmS under conventional HDS conditions because the hydrodesulfurization of the reactive sulfur species contained in the fraction was hardly inhibited by the aromatic compounds. In contrast, the heavier fraction was very hard to be hydrodesulfurized since its refractory sulfur species were strongly inhibited by large content of aromatic components. Dilution of the heavier fraction with common solvents showed higher reactivity over NiMo/Al₂O₃ catalyst than itself alone. Decalin, which showed the highest dilution effect, was believed to strip the strongly adsorbed aromatics off from the catalyst surface.     

Gel permeation chromatography of polyoxymethylene

Gel permeation chromatography of polyoxymethylene has been studied using N,N-dimethylformamide as the solvent. Polyoxymethylene samples used here are a copolymer of tetraoxane with 1,3-dioxolane and a commercial polyoxymethylene whose molecular weight distributions are moderately broad. Their intrinsic viscosities [η] range from 1.4 to 2.8 dl/g. Factors affecting chromatograms are discussed, and the operating conditions were determined by using the analytical scale GPC. On the basis of these operating conditions, the molecular weight fractionation of polyoxymethylene was carried out by using the preparative scale GPC. It was found that polyoxymethylene can be effectively fractionated to give seven to ten fractions each of them containing the fractionated polymer ranging in weight from 0.2 to 8 mg when 40 mg polymer sample was used for a run of the measurement. The fractionated polymers were also found to have a narrow molecular weight distribution within a single peak, and their M_w/M_n values decrease with increasing molecular weight.     

High-Temperature Formation Phases and Crystal Structure of Hot-Pressed Thermoelectric CuGaTe<Subscript>2</Subscript> with Chalcopyrite-Type Structure

Polycrystalline CuGaTe₂ with a chalcopyrite-type structure consolidated by hot-pressing is a potential candidate as a medium-temperature thermoelectric (TE) material. However, its high-temperature formation phases have rarely been reported to date. Here, we investigated the temperature-dependent formation phases and crystal structure at 300–800 K of hot-pressed CuGaTe₂. From synchrotron x-ray diffraction data and crystal structure analysis of the heating and cooling processes, it was clarified that a certain amount of impurity phases, such as Te and CuTe, precipitated from the CuGaTe₂ matrix when the temperature was increased (to 500–650 K). This is the temperature range where CuGaTe₂ has been reported to show high TE performance. After CuGaTe₂ was heated to 800 K, such impurity phases remained, even when cooled to room temperature. They also affected the tetragonal distortion and the x-coordinate of Te in the CuGaTe₂ matrix, probably due to deficiencies of Cu and Te in the matrix. Our results reveal detailed information on the formation phases of CuGaTe₂ at high temperature and thus provide insight for evaluation of its high-temperature stability and transport properties.