bluuebunny/crossref_metadata_2025 huggingface dataset:
Desdoblado de dolor: estética de la anestesia
Authors: González Fernández Francisco
Published: December 2018

A lo largo del siglo XIX el tema literario del doble experimenta un cambio notable, tanto por el ínsólito incremento del número de relatos dedicados a este personaje como por la naturaleza siniestra que adquiere entonces. Entre los múltiples factores que favorecieron la aparición de este doppelgänger destacan los avances y descubrimientos que se produjeron en esos años en el campo de la medicina, especialmente en lo concerniente al dolor y a su posible supresión. La manifestación del sufrimiento produce en el paciente una sensación de despersonalización y disociación que lo lleva a identificar su sufrimiento con un “ello”, como si fuera un antagonista, como si del dolor emergiera un doble. El descubrimiento de la anestesia hacia 1850 trajo consigo la reevaluación de la experiencia del dolor, que dejó de ser entonces considerado como inseparable de la vida. La capacidad para eliminar el sufrimiento propició su objetivación, y numerosos poetas y novelistas convirtieron la antigua y legendaria figura del doble en el receptáculo donde hicieron cristalizar sus efectos disociativos.
Análisis del discurso, literatura y ciencia
Authors: Maingueneau Dominique
Published: December 2018

Este artículo intenta presentar las características mayores del análisis del discurso literario, que se ha desarrollado desde hace una veintena de años en el interior del campo del análisis del discurso. Comienza situando el análisis del discurso literario en relación con la estilística tradicional, para subrayar que un análisis centrado sobre la noción de discurso subvierte la oposición entre texto y contexto, y por tanto entre aproximaciones internas y externas a los textos literarios. En un segundo momento, muestra que la aparición del análisis del discurso literario modifica la configuración de los estudios literarios, los cuales mantienen por naturaleza una relación ambigua con las ciencias humanas y sociales. Todo invita a distinguir dos paradigmas en el estudio de la literatura: un paradigma hermenéutico que se centra en la relación entre ciertas obras privilegiadas y sus intérpretes, y un paradigma discursivo que aprehende el discurso literario como una red de prácticas históricamente situadas.
Ciencia y paraciencia en la imagen: Alexander Tsiaras, Anatomical Travelogue/The Visual MD
Authors: González de Ávila Manuel
Published: December 2018

La creación de imágenes científicas es uno de los ámbitos más activos dentro de la cultura visual. Este artículo describe, en su primera parte, las cuatro dimensiones principales de la imagen científica (las dimensiones cognitiva, constructiva, pragmática y estética), para poner el énfasis al final de su descripción en la presente convergencia de la ciencia y del arte. En su segunda parte analiza un conocido caso de imagen paracientífica actual, donde a través de una específica combinación de dichas cuatro dimensiones comparecen ejemplarmente buen número de las obsesiones a la vez epistémicas y políticas de la contemporaneidad.
Microstructural Characteristics of Laser Metal Deposited Magnesium Alloy AZ31
Authors: Riekehr Stefan , Ventzke Volker , Konovalovna Anna , Kashaev Nikolai , Enz Josephin
Published: December 2018

Up to now, only a limited amount of metallic materials is investigated for laser additive manufacturing (LAM). However, the demand to widen the application possibilities by enlarging the range of materials for LAM is growing fast. By now, titanium and aluminium alloys are in the focus of research. In contrast, magnesium alloys are rarely used in the field of additive manufacturing, although they possess a low density in combination with a high specific strength. Currently, magnesium structures are mainly produced by casting but during the last years, the use of wrought alloys also increased. A reason for the rare use of magnesium alloys for LAM technologies might be the high flammability of magnesium powders. This difficulty can be avoided by using magnesium wire for laser metal deposition (LMD). In the present study, the microstructural characteristics of a LMD processed AZ31 magnesium alloy are investigated. For this purpose, optical microscopy and scanning electron microscopy were used. With the help of EDX and EBSD analysis, a change of the chemical composition and micro texture with structure height was identified. The relationship of microstructure and local mechanical properties was investigated with the help of Vickers micro hardness testing. Based on the obtained results it can be concluded that the microstructural characteristics of laser additive manufactured magnesium alloys differ from those of titanium and aluminium alloys. Thus, a wider application spectrum of LMD and magnesium alloys can be opened up.
Effect of Heat Processing Technique on Microstructure and Mechanical Properties of Extrusion Beta Titanium Alloy Tube Blank
Authors: Qi Yun Lian , Zeng Li Ying , Du Yu , Xin She Wei , Liu Wei , Sun Hua Mei
Published: December 2018

The effects of extrusion temperature and heat treatment on the microstructure and mechanical properties of beta-CEZ titanium alloy tube blank were studied with an emphasis on the relationship between the heat processing technique and microscopic structure. The results show that the extruded tube blank of beta-CEZ titanium alloy at alpha-beta phase has better tensile strength and plasticity match, and the ductility of the alpha-beta phase extrusion is obviously better than that of the single beta-phase extrusion, especially the reduction of area. When the extruded tube is heat treated at 830°C and 860°C solid solution, with the increase of aging temperature, the strength of tube decreases and the plasticity increases. When the aging temperature is up to 600°C, the reduction of area of the tube increases obviously. When the extruding tube is aged at 550°C and 600°C, the strength of the tube increases and the plasticity decreases with the increase of the solid solution temperature. The titanium alloy of beta-CEZ is extruded below the phase transition point after low temperature solid solution and high temperature aging treatment, which can achieve good microstructure and performance matching. The tensile strength is greater than 1250MPa, the elongation is more than 15%, and the reduction of area is more than 40%. The microstructure was a fine and uniform equiaxed structure.
Thermal Analysis for the Prediction of Grain Refinement: An Experimental Investigation on an AlSiMg Foundry Alloy
Authors: Lattanzi Lucia , Fortini Annalisa , Giovagnoli Maverick , Merlin Mattia , Pirletti Stefano , Morè Spreafico Stefano , Garagnani Gian Luca
Published: December 2018

Thermal analysis is widely used as a prediction tool for the quality of Al alloys before casting. In the present work, the effects of different grain refiners on the characteristic temperatures and on the grain size of α-Al phase were studied by thermal analysis and metallographic investigations. The response of an AlSiMg alloy towards grain refiners, added in form of rods and tabs, was investigated. In foundry practice, the fading phenomenon of grain refiners is well-known but not completely understood. For these reasons, the fading effect of each refiner at 60 minutes and 120 minutes holding times was also studied. Cooling curves and their derivatives were obtained during solidification of the alloys in a metallic crucible. Experimental data indicated the increase of the temperature associated with the nucleation of α-Al dendrites for the grain-refined alloys in comparison to the untreated ones. Simultaneously, a decrease in primary Al growth temperature, that led to the disappearance of the minimum temperature, were observed. Microstructural features revealed that an increase of 6 ÷ 7 °C of the nucleation temperature, compared to the not refined alloy, corresponds to a significant decrease in average grain size.
The DSC Investigation on Phase Transformations of Directionally Solidified (DS) and Powder Metallurgy (PM) Ni-Base Superalloys
Authors: Zheng Liang , Liu Yu Feng , Gorley Michael J. , Hong Zu Liang , Day Sarah , Tang Chiu C. , Li Zhou , Xiao Cheng Bo , Zhang Guo Qing
Published: December 2018

The phase transformations of the directionally solidified (DS) and powder metallurgy (PM) Ni-base superalloys were investigated by JMatPro, synchrotron XRD (SXRD) and differential scanning calorimetry (DSC). The minor phases, such as MC, eutectic γ′ and Ni5Hf, and γ matrix with secondary γ′ existed in as-cast microstructure of DS DZ22. However, only γ matrix was found in PM625 alloy powders. The phase change in both heating (melting) and cooling (solidification) process was investigated by DSC on DZ22 test bar and PM625 alloy powders respectively. The DSC experiment with different heating/cooling rates (5-40°C/min) was performed on DS superalloy DZ22. The results indicated that the heating/cooling rate had obvious effect on the DSC results of the phase transformation temperatures of liquidus, MC carbides, solidus, eutectic (γ+γ′) and secondary γ′. The heating and cooling DSC curves shifted to high and low temperature direction respectively, accompanied by the heating/cooling rate increased. However, the average values of specific peaks of heating and cooling curves are relatively consistent which is close to the equilibrium phase change temperatures of the alloy and makes the results comparable. Besides the average value method, the liquidus temperature of the alloy (0°C/min) can also be obtained by method of linear-fit/extrapolating from 5-40°C/min heating/cooling rates or inflection point deviate from the baseline of DSC cooling curves which could minimize the heating/cooling rate effects. The DSC experiment was carried out on PM625 superalloy powders with different particle size range (0-355μm), the results indicated that the particle size had minor effect on liquidus and solidus temperatures of DSC heating curves, the differences were less than 2°C. The change in phase transformation temperatures under different heating/cooling rate should be considered for selecting the process parameter (heat treatment, HIP or casting) for manufacturing Ni-base superalloy components.
An Innovative Industrial Process for Forging 7050 Al Alloy
Authors: Tedde Giovanni Matteo , Di Schino Andrea , Donnini Riccardo , Montanari Roberto , Richetta Maria , Santo Loredana , Testani Claudio , Varone Alessandra
Published: December 2018

The effect of an unconventional thermal treatment method aimed to improve toughness behavior in Al alloys is reported. The method involves solution heat treating and an intermediate warm working step, before final ageing thermal treatment on a AA7050 high resistance aluminum alloy. Results show the possibility to increase fracture toughness behavior without tensile and conductivity (IACS) properties loss by adopting a warm deformation process instead of the standard cold deformation. Moreover, the adoption of an intermediate warm deformation instead of standard cold deformation, allows to reduce material microstructural grain-size heterogeneity.
Characterization of Powder Metallurgy High-Entropy Alloys Prepared by Spark Plasma Sintering
Authors: Moravcikova-Gouvea Larissa , Moravcik Igor , Cizek Jan , Krajnakova Petra , Jan Vít , Dlouhy Ivo
Published: December 2018

In the present work, the High-Entropy Alloys Al0.2Co1.5CrFeNi1.5Ti, Al1.3Co1.4Cr2.0FeNi4.0Ti4.0 and Al6.0Co1.2Cr2.5FeNi3.5Ti6.0 were produced by Mechanical Alloying and subsequent Spark Plasma Sintering processes to obtain properly densified bulks. The characterization of the materials was accomplished through X-Ray Diffraction, Scanning Electron Microscopy, microhardness and nanoindentation tests to identify and analyze the acquired microstructures’ features, phases formed, morphology and size of the grains and its average hardness. The results indicate that it was possible to obtain alloys presenting high values of hardness and multi-phase microstructures. The effect of the multiple phases on the microstructures was discussed in terms of its influence on the mechanical properties. A satisfying densification level of the materials was achieved with the selected parameters.
Effect of Ti on the Microstructure and Mechanical Properties of a Hot Rolled Advanced High Strength Steel Strip
Authors: Smith Ali , Vercruysse Florian , Petrov Roumen , Verleysen Patricia , Linke Bernd
Published: December 2018

The addition of titanium is a well-known microalloying concept for hot rolled structural steels. Concerning advanced high strength steels for the automotive sector, the use of Ti microalloying (usually with Nb-V) has been an active research area. However, Ti addition has not been explored in depth. For the current contribution, a laboratory hot rolled 0.2C-2.4Mn-1.5Si steel with and without Ti addition was studied. Mechanical testing of the hot strip revealed a very high UTS (1GPa) for the Ti added steel, whilst for the unalloyed chemistry the UTS was some 300 MPa lower. Observation of the hot rolled microstructures via optical microscopy showed a significantly higher hardenability for the Ti added steel. Moreover, X-ray diffraction analysis indicated a significant amount of retained austenite in the Ti added strip, which transformed completely to martensite after the tensile test. Further analysis via TEM and chemical extraction indicated that Ti was present both as Ti (C,N) precipitates and in solution. Finally, in light of these observations, the possible mechanisms leading to the enhanced hardenability observed for the Ti added hot rolled strip steel were discussed.
Cost-Effective Production of High-Property Titanium Alloy from Powder
Authors: Singh Ajit Pal , Yang Fei , Torrens Rob , Gabbitas Brian , Bolzoni Leandro
Published: December 2018

Blended Elemental Powder Metallurgy is a very attractive method for producing titanium alloys, which can be formed near net shape and have freedom in composition selection. However applications are still limited due to affordability. In this paper, we will discuss a possible cost-effective route, combining vacuum sintering, extrusion, and heat treatment, to produce titanium alloys with similar or better mechanical properties than that of ingot metallurgy titanium alloys. The as-processed material with an oxygen content of 0.34 ± 0.005 wt.% was subjected to heat treatments such as β annealing plus ageing and α+β annealing without ageing to attain a typical lamellar/Widmanstätten/basketweave type structure with a large variation in terms of the microstructural features such as grain size, colony size, inter-lamellar spacing, thickness of grain boundary α, and size of individual lamellar. From mechanical property data attained here, it was apparent that annealing in high α-β region gave a much better combination of mechanical properties: yield strength (860-902 MPa), ultimate tensile strength (1060-1084 MPa) and ductility/plastic strain (11.5-13.6%). The hardness values of heat treated material varied between 346-376 Vickers hardness (36.8-44.5 Rockwell hardness).
Surface Defect Formation in Steel Continuous Casting
Authors: Zappulla Matthew L.S. , Thomas Brian G.
Published: December 2018

Serious defects in the continuous casting of steel, including surface cracks and depressions, are often related to thermal mechanical behavior during solidification in the mold. A finite-element model has been developed to simulate the temperature, shape, and stress of the steel shell, as it moves down the mold in a state of generalized plane strain at the casting speed. The thermal model simulates transient heat transfer in the solidifying steel and between the shell and mold wall. The thermal model is coupled with a stress model that features temperature-, composition-, and phase dependent elastic-visco-plastic constitutive behavior of the steel, accounting for liquid, δ-ferrite, and γ-austenite behavior. Depressions are predicted to form when the shell is subjected to either excessive compression or tension, but the shapes, severity, and appearance differ with conditions. Cracks appearing without depressions are suggested to form in the lower ductility trough when the shell is colder but more brittle. The local thickness of the shell and austenite layer appears to have major effects as well. The model reveals new insights into the formation mechanisms and behavior of surface depressions and longitudinal cracks in the continuous casting process.
Natural Aging Behavior of Double-Sided MIG Welded A7N01-T5 Aluminum Alloy
Authors: Li Ying , Zhang Zhi Qiang , Liu Jian , Yin Hua , He Chang Shu
Published: December 2018

A heat treatable A7N01 (Al-Zn-Mg) aluminum alloy mainly used to fabricate high-speed train body structures was double-sided welded by MIG welding. The natural aging behavior of the joint was systematically studied by local and global mechanical property testing method. Based on TEM observation and EPMA analysis, the key factors that lead to different natural aging behavior among various regions of the joint were discussed. The global tensile strength of the joints increased obviously after natural aging. All the joint samples fractured in the weld zone, which demonstrated the weld zone was the weakest zone of the joints. And the strength of the global welds were depended on the microstructure and natural aging ability of the weld zone. Moreover, the increase of the tensile property of the three local regions in the weld zone after post natural aging decreased as Middle>lower>upper. The above phenomenon was also further confirmed by microhardness measurement. The age hardening behavior is greatly influenced by the concentration of strengthening precipitates forming element Zn. The Zn content in the weld zone determined by EPMA showed that element Zn was dispersed unevenly, which is attributed to the double V-groove design used in this work and Zn vaporization in the molten pool during welding. The Zn content in the middle layer metals is higher than that of the upper and lower layers, resulting in the remarkable hardening response for the middle layer of the weld zone during natural aging process. Additionally, the solution zone containing the same Zn content as the base metal and undergoing sufficient solid solution during welding was found to possess the high hardening ability after natural aging process.
The Relationship between Mg Content and Extra-Hardening in Ultrafine Grained Al-Mg Alloy by SPD
Authors: Suzuki Yuto , Shiono Yuichi , Morishige Taiki , Takenaka Toshihide
Published: December 2018

Severe Plastic Deformation (SPD) process is one of methods for obtaining UFG-Al. It was reported in SPD-processed Al alloy that the extra-hardening due to work hardening caused by accumulated dislocation in the grains. In Al-Mg alloy, Mg decreases the stacking fault energy in this alloy, and dislocation tends to accumulate in the grains. In this study, Al-Mg alloy with various Mg contents were processed by Equal-Channel Angular Pressed (ECAP) which was one of SPD and annealed after processed ECAP. The relationship between Mg content and magnitude of extra-hardening was investigated. In ECAPed Al-3mass%Mg alloy, it was thought that extra-hardening was caused. Magnitude of extra-hardening was increased with increasing Mg content.
Microstructure Evolution and Texture Formation Behavior during High-Temperature Deformation in M1 Magnesium Alloy
Authors: Lee Kyu Jung , Lee Jeong Hoon , Kim Kwon Hoo
Published: December 2018

Uniaxial compression tests are carried out in the M1 magnesium alloy at 723K under a strain rate of 5.0x10-2s-1 up to a strain of-1.3. Microstructure observation shows that grain distribution is heterogeneous and coarsened grain is observed in all deformation conditions. Mean grain size tends to decrease with increasing strain. Dynamic recrystallization and grain growth are occurred during deformation. (0001) texture which shown at annealed state is weakened with increasing strain, and texture component changed from (0,0) to (24,0) during deformation. The recrystallized grains have no strong preferred orientation about (0001), similar to the grains of growing.
Effect of Voltage on Mg-Li-Al Alloy Anodic Oxide Film
Authors: Miyakita Naoya , Tanigaki Natsuki , Morishige Taiki , Takenaka Toshihide
Published: December 2018

Anodic oxidation of Mg-Li-Al alloys using phosphoric acid-based bath were processed to obtain the corrosion-proof surface coating. The specimen oxidized at low voltage anodically dissolved without the formation of oxidized film. Anodic oxidation film could be formed at higher voltage due to thin layer preferentially formed on tthe active surface, this layer develops to stable thick film. There were no significant differences in film thickness between LA141 and LA143 alloys.
Nucleation Effect of Ca-Oxysulfide Inclusions of Low Carbon Steel in Heat Affected Zone by Welding
Authors: Terazawa Yusuke , Ichimiya Katsuyuki , Hase Kazukuni
Published: December 2018

In order to achieve excellent toughness of heat affected zone (HAZ) of low carbon steel plates by welding, several microstructure control techniques using fine particles have been developed. In particular, Ca-oxysulfide inclusions have been used in a lot of steel plate products, because they are thermally stable even in near the fusion line of weld joint and they have grain refining effect in HAZ. In cases where heat input is large (>100kJ/cm) and microstructure of HAZ mainly consists of polygonal ferrite, it has been clarified that Ca-oxysulfide inclusions act as nucleation sites of polygonal ferrite in HAZ during the cooling process after welding. However, in cases where heat input is medium (≈50kJ/cm) and microstructure of HAZ mainly consists of bainite, nucleation effect of Ca-oxysulfide inclusions and that of mechanism have not been clarified. This study investigated the nucleation effect of Ca-oxysulfide inclusions in medium heat input welding by in-situ laser microscope observation and the lattice misfit between Fe-matrix and Ca-oxysulfide inclusions.
Preparation of TiAl Intermetallic Alloy Precursor Using Slow Reaction Synthesis Process
Authors: Shimizu Toru
Published: December 2018

Already, there are several processes to produce intermetalic alloy parts from powder , ex. metal injection molding (MIM) or additive manufacturing (AM). For these processes, pre-alloyed powder made by gas atomized powder is used because of their quality. As other way, intermetallic alloy can be produced combustion reaction process. On this process, ingredient metal powders are mixed and reacted by combustion. However, powders are fused by reaction heat, and they are difficult to keep the powder condition. There for, we are developed the process to produce intermetallic alloy precursor by slow combustion reaction. On this process, temperature of mixed powders increases slower than 0.2K/sec. while the combustion reaction, and powders are reacted without fusing. Using this process, TiAl presursor is synthesized. Relation of reacting condition and quality of the precursor is evaluated, and researched the practical usage of this precurser.
Relationship between Microstructure and Magnetic Properties of Nano-Scale Particles Formed in Cu-Ni-(FeCo) Alloys
Authors: Matai Shintaro , Sakakura Hibiki , Takeda Mahoto
Published: December 2018

Numerous studies have been conducted to develop next-generation recording technology in spintronics. Because ultrafine magneitc particles are vital components of the technology, the interplay between the microsturcture and magnetic properties has attracted attention extensively in recent years. We focused on the relationship between the microstructure and magnetic properties of Cu-Ni-X (X=Fe, Co, FeCo) alloys comprising nanogranular magnetic particles. In this work, we prepared Cu-20 at% Ni-5 at% (FeCo), Cu-20 at% Ni-5 at% Fe, Cu-20 at% Ni-5 at% Co and examined the changes of microstructure and magnetic properties associated with heat treatments and composition. To examaine microstructural evolution of the alloy specimens, we conducted transmission electron microscope observations (TEM) with the as-quenched specimens and those aged at at 773-1073 K. We also carried out magneto-thermo gravimetry (MTG) measurements, superconducting quantum interference device (SQUID) measurements, magnetoresistance (MR) measurements and first-principles calculations based on the Koster-Korringa-Rostker (KKR) method with the Coherent Potential Approximation (CPA), to investigate the magnetic properties. The present work confirmed that the microstructure significantly changed, depending on the composition and heat treatment conditions. The present work also revealed that the magnetic properties closely correlated with the microstructure of samples.
Dynamic Recrystallization during Warm Accumulative Asymmetric Roll Bonding (AARB) of the AA1050 Aluminium
Authors: Kliauga Andrea Madeira , Godoi Renan P. , Sordi Vitor Luiz , Bolmaro Raul E.
Published: December 2018

In this work asymmetric accumulative roll bonding (AARB) was applied to a AA1050 aluminum up to ten cycles at 350 and 400°C. The texture was measured by x ray diffraction and EBSD. Hardness and tensile tests characterized the strain distribution and bonding efficiency. At 350 °C the microstructural refinement was stabilized after four cycles and mean grain sizes of one micron and a saturation yield strength of 160 MPa was achieved. At 400°C grain growth took place yielding a bimodal microstructure with mean grain size of 9 microns. During repeated bonding cycles recovery and dynamic recrystallization were observed and extra shear in the interfacial region yielded a fairly well homogeneous strain distribution and weak shear texture across the sheet for both temperatures. The strongest component in both cases was the rotated cube orientation. The last bonding surface was the weakest bond but adding an extra 50% reduction step to the process increased the interfacial strength considerably.
Evolution of Young’s Modulus of Cold-Deformed Pure Aluminium in a Tension Test
Authors: Isarn Isaac , Jorba Jordi , Roca Antoni , Llorca-Isern Nuria
Published: December 2018

Young’s modulus varies with crystallographic orientation, temperature and alloying, but also with cold working and heat treatment. In this work, the evolution of Young’s modulus in polycrystalline pure aluminium (99.5%) with different cold-working levels determined at room temperature is presented. The deformation process was carried out in a universal tension machine and measurements were performed by ultrasounds. The Young’s modulus diminished from 70 to 65 GPa for 0-5% of deformation (elongation) and then increased with successive cold-working (68 GPa for 8.5% of elongation). These values were obtained 8 hours after plastic deformation was applied. This behaviour is compared with the Young’s modulus determined by extensometry in the same material. In this case, the modulus decreased from 70 to 63 GPa (3.5% of elongation) and then increased until 68 GPa for 10% of elongation. Results obtained on pure iron (Armco) deformed in the same conditions are included for comparative purposes. Values of Young’s modulus measured during the springback process after plastic deformation at different level are also included. Values obtained are between 10-15% lower than those measured 8 hours after plastic deformation.
Effects of Mo Addition on Deformation Behavior of Metastable Beta-Type Ti-Mn Single Crystals
Authors: Morioka Ryota , Cho Ken , Yasuda Hiroyuki Y.
Published: December 2018

In this study, to clarify the effects of Mo addition on deformation behavior of Ti-Mn alloys, the mechanical properties and the deformation structures of the alloys were investigated using Ti-Mn and Ti-Mn-Mo alloys polycrystals and single crystals. We found that the elongation of Ti-Mn alloys are improved from approximately 5% to 30% by Mo addition, with maintaining ultimate tensile strength of 900 MPa. The excellent strength-ductility balance of Ti-Mn-Mo alloys is caused by {332}<113> twinning, which is unique twinning for metastable β-type titanium alloys. Additionally, the deformation behavior of Ti-Mn and Ti-Mn-Mo alloys was investigated in detail by using single crystals focusing on a critical resolved shear stress (CRSS). As a result, we found for the first time that CRSS for {332}<113> twinning in Ti-Mn-Mo alloy was lower than that in Ti-Mn alloy. Moreover, in Ti-Mn-Mo alloy, CRSS for {332}<113> twinning was lower than that for {112}<111> slip. These results suggest that CRSS for {332}<113> twinning in Ti-Mn alloys is decreased by Mo addition.
Effects of Heat Treatment on Unique Layered Microstructure and Tensile Properties of TiAl Fabricated by Electron Beam Melting
Authors: Sakata Masahiro , Oh Jong Yeong , Cho Ken , Yasuda Hiroyuki Y. , Todai Mitsuharu , Nakano Takayoshi , Ikeda Ayako , Ueda Minoru , Takeyama Masao
Published: December 2018

In the present study, effects of heat treatment on microstructures and tensile properties of the cylindrical bars of Ti-48Al-2Cr-2Nb (at.%) alloy with unique layered microstructure consisting of equiaxed γ grains region (γ band) and duplex-like region fabricated by electron beam melting (EBM) were investigated. We found that it is possible to control width of the γ bands (Wγ) by heat treatments at 1100°C and 1190°C. The Wγ increases with decreasing heat treatment temperature. The bars heat-treated at 1190°C exhibit high elongation of 2.9% at room temperature (RT) with maintaining high strength. The RT elongation increases with increasing the Wγ because of increasing deformable regions. In contrast, the RT elongation of the bars decreases with increasing the Wγ when Wγ is very large. This is because the large γ band leads intergranular fracture. These results indicate that there is appropriate width for the γ band to obtain excellent tensile properties at RT.
Deformation Behavior of Fe-Al Single Crystals Containing Fe2AlTi Precipitates
Authors: Yasuda Hiroyuki Y. , Yakage Hiroyuki , Shinohara Yunima , Cho Ken
Published: December 2018

Fe-20Al-5Ti (at.%) single crystals composed of the bcc Fe-Al matrix and the Fe2AlTi precipitates with the L21 structure was examined. In the single crystals furnace-cooled (FC) from 1373 K to room temperature, coarse Fe2AlTi phase about 300 nm in diameter were precipitated in the bcc matrix. A misfit strain and a dissolution temperature of the L21 precipitates are +0.59% and 1151 K, respectively. The single crystals exhibited high yield stress above 600 MPa up to 973 K while further increase in temperature resulted in a decrease in yield stress due to the dissolution of the precipitates. In the FC crystals, 1/2<111> dislocations in the bcc matrix bypassed the coarse L21 precipitates due to their large misfit strain, resulting in high strength. In contrast, the fine L21 precipitates about 30 nm in diameter were observed in the crystals after solutionization and annealing at 873 K. The crystals with the fine L21 precipitates demonstrated high yield stress above 1100 MPa at and below 773 K. Uncoupled or paired 1/2<111> dislocations cut the fine L21 precipitates, leaving an anti-phase boundary (APB) inside the precipitates. The APB inside the precipitates was considered to be responsible for strong precipitation hardening.
Transport and Thermodynamic Properties of CeRu2Al10 Controlled by Pressure at around Critical Pressure
Authors: Kawamura Yukihiro , Sekine Chihiro , Matsubayashi Kazuyuki , Uwatoko Yoshiya , Nishioka Takashi
Published: December 2018

We present transport and thermodynamic properties of CeRu2Al10 controlled by pressure in a vicinity of a critical pressure PC ~ 4GPa, where antiferromagnetic ordering disappears. The resistivity under pressure was measured with DC four terminal method and the AC specific heat under pressure was measured by Joule heating type technique. The pressure was applied by cubic-anvil-apparatus and palm-cubic-anvil-apparatus. The results of AC specific heat indicate TN holds at high temperature up to 3.9 GPa but suddenly disappears above this pressure. We confirmed TN from thermodynamic properties. Although CeRu2Al10 is in a Kondo semiconducting ground state at 4 GPa, temperature dependences of electrical resistivity at 4.6 GPa and 5.9 GPa indicate metallic ground state in these pressures. CeRu2Al10 does not show superconductivity down to 0.7 K at 4.6 GPa and 5.9 GPa.
Hot Deformation and Dynamic Recrystallization in Titanium Aluminide
Authors: Bibhanshu Nitish , Suwas Satyam
Published: December 2018

The hot workability of gamma titanium aluminide alloy, Ti-48Al-2V-2Nb, was assessed in the cast condition through a series of compression tests conducted over a range of temperatures (1000 to 1175 °C) and at the strain rate of 10 S-1. The mechanism of dynamics recrystallization has been investigated from SEM Z-contrast images and from the Electron backscattered diffraction EBSD as well. It has been observed that volume fraction of the recrystallized grains increases with increasing the deformation temperature. The major volume fraction of the recrystallized grains was observed in the shear band which was forming at an angle 45 ̊ with respect to the compression direction. The mechanism of breaking of the laths and the region of the dynamic recrystallization were also investigated from the SEM Z-contrast image and EBSD. The dynamic recrystallization occurred in the region of the broken laths and shear bands. The breaking of the laths was because of the kinking of the lamellae. The shear band, kinked lamellae and dynamic recrystallized region where all investigated simultaneously.
Evaluation of Nanosize NbC Precipitates in HSLA Steel through Microstructural Analysis and Small Angle Neutron Scattering
Authors: Nakamichi Haruo , Yamada Katsumi , Okuda Kaneharu , Ishida Toshinori , Ohnuma Masato
Published: December 2018

Nano size precipitate morphologies are very important for considering the precipitate hardening mechanism of HSLA steels. Systematic analysis of precipitates from nano scale to bulk scale were carried out using Nb bearing hot rolled steels through transmission electron microscopy (TEM) observations and chemical analysis of precipitates by solvent extraction. A small angle neutron scattering (SANS) experiment was also performed using a Hokkaido Univ. compact neutron source to understand average precipitate size. Results show that both changes in hardness and the amount of precipitates (under 20nm in size) have the same tendency. Precipitate is recognized as NbC plates, which have coherency with the steel matrix by Baker-Nutting orientation relationships. A row of precipitates, formed on the interface between austenite and ferrite during transformation, is also apparent. The SANS profile shows that small size precipitate formation is detected even though the amount of precipitation is small. In addition, the magnetic scattering component of the SANS profile has high sensitivity to NbC precipitates compared with that of the nucleus scattering component. By comparing precipitate data from comprehensive experiments, we consider the relationship between precipitate behavior and the hardening mechanism.
Simulation of Thermal Phenomena in Reverse Strip-Rolling Process
Authors: Nam Alexander , Prüfert Uwe , Pietrzyk Marciej , Kawalla Rudolf , Prahl Ulrich
Published: December 2018

In the reverse hot strip rolling, the coiling and uncoiling of the strip leads to unstable conditions during the forming process. Both the temperature of the strip and the dwell time in the coil vary and influence the microstructure evolution passing in the coil during reverse rolling. It makes the design of this process difficult. Therefore, development of the temperature model for the reverse hot rolling including coiling and uncoiling was the main objective of the paper. The identification of the unknown parameters of the boundary conditions is proposed. Methods for their determination are discussed. The analysis is performed on example of the reverse hot rolling of the magnesium alloy AZ31. The resulting temperature model reveals good agreement with thermocouple and pyrometer measurements.
Simultaneous Prediction of Bendability and Deep Drawability Based on Orientation Distribution Function for Polycrystalline Cubic Metal Sheets
Authors: Inoue Hirofumi
Published: December 2018

Sheet metal formability is generally affected by crystallographic texture. In particular, bendability and deep drawability of metals and alloys are closely related to the recrystallization texture of the rolled sheets. It is necessary to quantitatively predict them from a viewpoint of texture control. This study proposes a method for simultaneous prediction of both the bendability and the deep drawability on the basis of the average Taylor factor as a polycrystal calculated by using an orientation distribution function. The normalized Taylor factor (Mn-value) and the r-value are used as measures of bendability and deep-drawability, respectively. The predicted results from ideal orientations demonstrated that {001} orientation had excellent bendability and poor deep drawability, whereas {111} orientation had poor bendability and excellent deep drawability. In addition, the predicted results for practical FCC and BCC metals indicated that cube texture in FCC metals was unfavorable for deep drawing and the γ-fiber texture of <111>//ND in BCC metals was unfavorable for bending.
TMP as an Effective Technique to Produce Ultra-Fine Grained Steels
Authors: Kodzhaspirov G.E. , Rudskoi Andrey
Published: December 2018

In recent years, great attention is paid to the creation of methods andthe technological processes providing ultrafine-grained state of metal materials including submicro - and nanocrystalline ones. It pertains to structural components and to the phases constituting the particular metal or alloy. The main development in terms of obtaining bulk metallic materials received in recent years, various schemes of processing of metals by plastic deformation, which allows to realize the so-called severe plastic deformation (SPD). Such approach usually propose realization of large plastic strains, providing a well-developed fragmented substructure with the creation of high angle misorientation of the boundaries between the fragments of the substructure. The second direction in receiving finely divided state is to create technologies that provide a significant refinement of phase as a result of processing. The most effective way of achieving both the above effects applied to bulk metallic materials is Thermomechanical Processing (TMP), which can be used as a standalone technology or in combination of such methods as accumulation roll bonding (ARB) or other similar SPD methods. This paper discusses various methods of thermomechanical processing, based on the use of hot, warm and cold deformation, in various combinations applied to single and multiphase steels, ensuring the achievement of ultra-fine grained structure with elements of submicro - and nanostructures.
Deformation Twinning and Change in Mechanical Properties of Cu-15at%Al in Multi-Pass Cold Rolling
Authors: Lee Sang Min , Im Yong Deok , Matsumoto Ryo , Utsunomiya Hiroshi
Published: December 2018

Recently, it was reported that Cu-Al alloys of low stacking fault energy (SFE) processed by severe plastic deformation show excellent tensile properties due to TWIP (Twinning induced Plasticity) phenomenon. In this study, Cu-15at% Al sheets were heavily processed by conventional multi-pass cold rolling up to 90% in reduction in thickness without annealing. In order to reveal the change in mechanical properties and the microstructure evolution, tensile test, hardness test, optical microscopy (OM) and electron backscattering diffraction (EBSD) analysis were performed. Deformation twinning due to low SFE is observed even in the case of low reduction in thickness. As the reduction increases, grains are refined by intersections of shear bands. It is found that the balance of strength and elongation of the processed sheets is comparable to those by severe plastic deformation followed by annealing in literature.
The Effect of Vibration Condition for Magnesium Dry Gravity Sorting by Vibrating Particulate Bed
Authors: Itoh Shingo , Tsujita Keigo , Morishige Taiki , Takenaka Toshihide
Published: December 2018

Recycling Mg alloys has been demanded as the demand of Mg alloys has been increased. It is difficult to separate Mg with Al because the properties are similar except for the density. In this study, gravity sorting by vibrating particulate bed ajusted the density to intermediate between Mg and Al was applied for Mg separation with Al. The relationship the vibrating condition and the sorting accuracy was investigated by applying different vibration acceleration and by applying the vertical and horizontal vibration. Turbulent flow was observed and the recovery rate was improved when vertical vibration with high acceleration was applied to the bed. Higher recovery rate was achieved when horizontal vibration was applied to the bed. This result suggested that the horizontal movement of particle affected the behavior of sorting materials and high recovery ratio was achieved by optimizing vibrational condition such as vibration acceleration and the direction of vibration.
Cold Spray Manufacturing for Structural Materials for High Field Magnet Production
Authors: Jay Olivier , Verdy Christophe , Trophime Christophe , Danlos Yoann , Debray François
Published: December 2018

Cold spray processing appears to be a highly promising manufacturing process for coils for high field magnet. Dense and sizable material can be obtained characterized by high mechanical properties and high electrical conductivity thanks to the chamber of deposition under helium atmosphere. A low oxygen content material is obtained and the tensile and conductivity tests highlight the significance of the thermal treatment for the manufacturing process optimization.
Fabrication of Cu-Al-Ni Shape Memory Alloy by Selective Laser Melting Process
Authors: Imai Ken , Ikeshoji Toshi Taka , Nakamura Kazuya , Nishida Motonori , Sugitani Yuji , Kyogoku Hideki
Published: December 2018

Additive manufacturing (AM) is a prominent technology in the industrial fields such as aerospace, medical, automotive and so on. Especially, selective laser melting (SLM) process is available to create three-dimensional complicated structures of various alloys such as stainless steel, titanium alloy, aluminium alloy, nickel-based superalloy and so on. And also, copper and copper alloys are used as a material for products with complicated shape, electrical components, and a heat exchanger because of having the high electrical conductivity and the high thermal conductivity. It is known that copper alloys show a good shape memory behaviour by adding Al, Ni and Zn. Especially, Cu-Al-Ni alloy shows a good shape memory properties at high temperature. However, it is difficult to fabricate high-density Cu-Al-Ni alloy by the SLM process. This is mainly because Cu-Al-Ni alloy has high elastic anisotropy and brittleness in polycrystalline state. In this research, the optimum fabrication condition of Cu-Al-Ni alloy by SLM process was investigated. The optimum laser power and scan speed were able to be found by evaluating the surface morphology, density and microstructure of the as-build specimens.The maximum density of the as-built specimen was 99.47%.
Selective Laser Melting of Inconel 718 under High Power and High Scanning Speed Conditions
Authors: Tachibana Yusuke , Ikeshoji Toshi Taka , Nakamura Kazuya , Yonehara Makiko , Kyogoku Hideki
Published: December 2018

Selective laser melting (SLM) process has advantages in building free shape and simplification of manufacturing process. Since Ni-base superalloys have lower ductility at lower temperature, it is difficult to produce the parts by means of other process like forging. Therefore, SLM process has already applied to produce Ni-base superalloy parts. However, SLM process needs a long process time comparing to casting and machining. One of the means to solve this problem is an application of the high scanning speed condition under high power laser output. In this research, the optimum fabrication condition of Inconel 718 superalloy by SLM process under high power and high scanning speed condition was investigated. As a result, the optimum fabrication condition was obtained using the process map. However, the relative density of the as-built specimen fabricated under high power and high scanning speed condition is lower than that of the as-built specimen fabricated under the condition of 300 W and 600 mm/s. This may be mainly due to the occurrence of gas-pores by key-hole like phenomenon in melt pool and the increase of spattering at high power and high scanning speed condition.
In Situ Synchrotron Analysis of Twinning Stresses in an Aged Mg-4.5Zn Alloy
Authors: Ferdowsi Mahmoud Reza Ghandehari , Wang Jun , Kada Sitarama R. , Wang Zhi Yang , Lynch Peter A. , Barnett Matthew R.
Published: December 2018

Aging increases the yield strength of aged Mg-Zn alloys. The effect of aging on the stress required for twinning is examined using in-situ transmission based synchrotron X-ray diffraction. The as extruded material was aged at variety of temperatures for different times. It is found that increasing sample diameter (thickness) results in peak broadening. The data are analysed to establish the evolution of twin volume fraction with stress. Results indicated an increase in twinning stress at 10% twin volume fraction in aged samples in comparison with non-aged condition. The investigation showed a strong relation between the macroscopic yield stress and the twinning stress (at 10% twin volume fraction).
Microstructure and Fatigue Properties of TiAl with Unique Layered Microstructure Fabricated by Electron Beam Melting
Authors: Cho Ken , Kobayashi Ryota , Fukuoka Takuma , Oh Jong Yeong , Yasuda Hiroyuki Y. , Todai Mitsuharu , Nakano Takayoshi , Ikeda Ayako , Ueda Minoru , Takeyama Masao
Published: December 2018

The effect of a unique layered microstructure consisting of duplex-like region and equiaxed γ grains (γ bands) on the fatigue properties of Ti-48Al-2Cr-2Nb alloy bars fabricated by electron beam melting (EBM) at an angle (θ) of 90° between the building direction and cylinder (loading) axis was investigated focusing on the layered microstructure and test temperature. We found the room temperature (RT) fatigue strength of the alloy bars fabricated at θ = 90° is higher than that of the bars fabricated at θ = 0°. Moreover, it is comparable to that of the cast alloys with hot isostatic pressing (HIP) treatment in low-cycle fatigue life region, even without HIP treatment. The high fatigue strength of the bars at RT is attributed to the γ band, which acts as a resistance for crack propagation directed perpendicular to the γ band. On the other hand, the fatigue strength of the bars at θ = 90° is lower than that of the bars at θ = 0° in low-cycle fatigue life region at 1023 K. This is because the γ bands dose not act as a resistance for crack propagation at 1023 K. Although the bars at θ = 90° exhibits low fatigue strength in the region at 1023 K, that value is comparable to that of HIP-treated cast alloys due to the fine grain size, which is one of the features for the alloys fabricated by the EBM.
Micro-Alloyed Steel for Forgings
Authors: Mengaroni Sabrina , Calderini Massimo , Napoli Giuseppe , Zitelli Chiara , Di Schino Andrea
Published: December 2018

To fulfill the industrial demand of forged steels with high tensile properties and microstructural requirements coupled with reduced cost, the possibility to increase the properties of C-Mn steels by means of precipitation strengthening as achieved by micro-alloying (and without the addition of expensive elements such as Mo and Cr) has been evaluated. In order to do that, the effect of V addition has been exploited by means of metallurgical modelling followed by a laboratory ingot manufacturing. Heat treatment has been designed aimed to achieve the desired target tensile properties. Results show that ASTM A694 F70 grade requirements can bel fulfilled by 0.15% V addition and a proper heat treatment in a ferrite-pearlite microstructure, representative of a forged component. Results are discussed in comparison to those of a similar steel without V addition.