bluuebunny/crossref_metadata_2025 huggingface dataset:
CItA: un Corpus di Produzioni Scritte di Apprendenti l’Italiano L1. Annotato con Errori
Authors: Barbagli A. , Lucisano P. , Dell’Orletta F. , Montemagni S. , Venturi G.
Published: November 2016

In this paper we present CItA the first corpus of written essays by Italian L1 learners in the first and second year of lower secondary school. CItA was annotated with grammatical, orthographic and lexical errors. The corpus peculiarities and its diachronic nature make it particularly suitable for computational linguistics applications and socio–pedagogical studies.
Enhancing the Accuracy of Ancient Greek WordNet by Multilingual. Distributional Semantics
Authors: Bizzoni Yuri , Del Gratta Riccardo , Boschetti Federico , Reboul Marianne
Published: November 2016

We discuss a method to enhance the accuracy of a subset of the Ancient Greek WordNet based on the Homeric lexicon and the related conceptual network, by using multilingual semantic spaces built from aligned corpora.
Deep Neural Networks for Named Entity Recognition in Italian
Authors: Bonadiman Daniele , Severyn Aliaksei , Moschitti Alessandro
Published: November 2016

In this paper, we introduce a Deep Neural Network (DNN) for engineering Named Entity Recognizers (NERs) in Italian. Our network uses a sliding window of word contexts to predict tags. It relies on a simple word-level log-likelihood as a cost function and uses a new recurrent feedback mechanism to ensure that the dependencies between the output tags are properly modeled. The evaluation on the Evalita 2009 benchmark shows that our DNN performs on par with the best NERs, outperforming the state of the art when gazetteer features are used.
Visualising Italian Language Resources: a Snapshot
Authors: Del Gratta Riccardo , Frontini Francesca , Monachini Monica , Pardelli Gabriella , Russo Irene , Bartolini Roberto , Goggi Sara , Khan Fahad , Quochi Valeria , Soria Claudia , Calzolari Nicoletta
Published: November 2016

This paper aims to provide a first snapshot of Italian Language Resources (LRs) and their uses by the community, as documented by the papers presented at two different conferences, LREC2014 and CLiC-it 2014. The data of the former were drawn from the LOD version of the LRE Map, while those of the latter come from manually analyzing the proceedings. The results are presented in the form of visual graphs and confirm the initial hypothesis that Italian LRs require concrete actions to enhance their visibility.
From a Lexical to a Semantic Distributional Hypothesis
Authors: Di Caro Luigi , Boella Guido , Ruggeri Alice , Cupi Loredana , Adebayo Kolawole John , Robaldo Livio
Published: November 2016

Distributional Semantics is based on the idea of extracting semantic information from lexical information in (multilingual) corpora using statistical algorithms. This paper presents the challenging aim of the SemBurst research project1 which applies distributional methods not only to words, but to sets of semantic information taken from existing semantic resources and associated with words in syntactic contexts. The idea is to inject semantics into vector space models to find correlations between statements (rather than between words). The proposal may have strong impact on key applications such as Word Sense Disambiguation, Textual Entailment, and others.
An Active Learning Approach to the Classification of Non-Sentential Utterances
Authors: Dragone Paolo , Lison Pierre
Published: November 2016

This paper addresses the problem of classification of non-sentential utterances (NSUs). NSUs are utterances that do not have a complete sentential form but convey a full clausal meaning given the dialogue context. We extend the approach of Fernández et al. (2007), which provide a taxonomy of NSUs and a small annotated corpus extracted from dialogue transcripts. This paper demonstrates how the combination of new linguistic features and active learning techniques can mitigate the scarcity of labelled data. The results show a significant improvement in the classification accuracy over the state-of-the-art.
Building a Corpus on a Debate on Political Reform in Twitter
Authors: Lai Mirko , Virone Daniela , Bosco Cristina , Patti Viviana
Published: November 2016

The paper describes a project for the development of a French corpus for sentiment analysis focused on the texts generated by the participants to a debate about a political reform, i.e. the bill on homosexual wedding in France. Beyond the description of the data set, the paper shows the methodologies applied in the collection and annotation of data. The collection has been driven by the detection of the hashtag mainly used by the participants to the debate, while the annotation has been based on polarity but also extended with the target semantic areas involved in the debate.
Le scritture brevi dello storytelling: analisi di case studies di successo
Authors: Pierucci Maria Laura
Published: November 2016

This paper presents an analysis of successful storytelling case studies. Their strategies and techniques of branding will be analyzed with an interdisciplinary approach, grounded on pragmatics of communication, within the conceptual framework of 'scritture brevi' as set in www.scritturebrevi.it.
Parsing Events: a New Perspective on Old Challenges
Authors: Sprugnoli Rachele , Dell’Orletta Felice , Caselli Tommaso , Montemagni Simonetta , Bosco Cristina
Published: November 2016

The paper proposes a new evaluation exercise, meant to shed light on the syntax-semantics interface for the analysis of written Italian and resulting from the combination of the EVALITA 2014 dependency parsing and event extraction tasks. It aims at investigating the cross-fertilization of tasks, generating a new resource combining dependency and event annotations, and devising metrics able to evaluate the applicative impact of the achieved results.
Reference-free and Confidence-independent Binary Quality Estimation for Automatic Speech Recognition
Authors: Zamani Hamed , de Souza José G. C. , Negri Matteo , Turchi Marco , Falavigna Daniele
Published: November 2016

We address the problem of assigning binary quality labels to automatically transcribed utterances when neither reference transcripts nor information about the decoding process are accessible. Our quality estimation models are evaluated in a large vocabulary continuous speech recognition setting (the transcription of English TED talks). In this setting, we apply different learning algorithms and strategies and measure performance in two testing conditions characterized by different distributions of “good” and “bad” instances. The positive results of our experiments pave the way towards the use of binary estimators of ASR output quality in a number of application scenarios.
Scenario of Quality Potato Production in Rajasthan
Authors: Jain Lokesh Kumar
Published: November 2016

Potato (Solanum tuberosum L.) is one of the most important non-traditional tuber crops of Rajasthan. The potato tuber is a modified stem developed underground on a specialized structure called stolen. It contributes to food and nutritional security and provide cheap source of vegetable. It is used either alone or intermingled with other vegetables. It is also consumed as many fried salted food items. Potato is a highly nutritious, easily digestible, wholesome food. In Rajasthan, where varied climatic conditions promoting cultivation of almost every crops and vegetables, the economic conditions of growers, lack of storage facilities and lack of improved technologies for the state remain as bottleneck for its cultivation. In this chapter I tried to elaborate the constraints and possible suggestion for increasing cultivation of potato which is fairly to highly responsive to inputs supplied and gave cash returns in short periods.
Agro-Geoinformatics, Potato Cultivation, and Climate Change
Authors: Dutta Upasana
Published: November 2016

The agriculture sector is reeling under the pressures of population, land and water scarcity, diseases, disasters and the most challenging of them all, climate change. Although climate change is yet to be charged with affecting agriculture, but in recent years trends of change have been witnessed in various crop production, with a hint of climate's role in it. With the advent of technology, these trends have become easier to analyse and in certain cases predict too. Information Technology (ICT) tools like Geoinformatics are playing a profound role in the agriculture sector and is helping to understand and assess the various factors affecting the growth of crops along with finding out the alternative suitability parameters for better production and distribution. The main aim of this chapter on agro-geoinformatics is to look into this linkage between technology usage and better potato production during adverse conditions.
The 3D Imaging and Metrology of Microstructural Elements in Innovative Materials for Clean Energy Systems and Aeronautics
Authors: Kruk Adam , Czyrska-Filemonowicz Aleksandra
Published: November 2016

The aim of this study was presentation the results of new tomographic techniques application to characterize structural elements in nickel-based superalloys for disc and blades using in aircraft engines and gas turbines in energy systems. Visualization of phases presented in as-service high chromium creep resistant steel for modern power plant applications was also performed using STEM-EDX and FIB-SEM electron tomography. Electron tomography (STEM-EDX) and FIB-SEM tomography were used for 3D imaging and metrology of the precipitates. Transmission electron microscopy and TEM-EDX spectroscopy were used to reveal details of the superalloys and steel microstructures and phases’ chemical compositions. The study showed that electron tomography techniques permit to obtain complementary information about microstructural features (precipitates size, shape and their 3D distribution) in the reconstructed volume with comparison to conventional particle analysis methods, e.g. quantitative TEM and SEM metallography.
Effect of Prior Austenite Grain Size on Yielding Behavior of the Low-C Martensitic Stainless Steel
Authors: Kubota Kazumasa , Ueda Masahito , Nakagawa Hideki
Published: November 2016

The effect of the prior austenite grain size on the yielding behavior of as-quenched low-C martensitic stainless steel was investigated. Martensite (Fe-16%Cr-7%Ni-1.2%Mo-1.8%Cu-0.01%C alloy) samples with different prior austenite grain sizes were prepared by heat treatment for various times at 1273K. The microstructures of the martensite were observed by optical microscopy, scanning electron microscopy, electron backscatter diffraction, and X-ray diffractometry. Tensile tests were undertaken at various test speeds. Also, a relaxation test was performed before the tensile tests to determine the behavior of mobile dislocations. A lower elastic limit was observed at lower test speeds and a larger prior austenite grain size. Moreover, a lower tensile strength was observed at a larger prior austenite grain size.
Osteoconductivity of Protein Adsorbed Titanium Implants Using Hydrothermal Treatment
Authors: Kuroda Kensuke , Okido Masazumi
Published: November 2016

Protein adsorption is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the osteoconductivity of protein adsorbed Ti surface is not completely clear. In this study, we produced the protein adsorbed Ti implants using hydro-processing. The hydrothermal treatment in the distilled water gave the super-hydrophilic Ti surface and they had much protein adsorbability. Fibronectin or albumin was picked up as a protein, which was cell adhesive protein and not cell adhesive, respectively. And also, the content of the adsorbed protein was evaluated by FT-IR (ATR) analysis. The water contact angle influenced the amount of the adsorption of the protein and the osteoconductivity of the samples were evaluated by in vivo testing.
Effect of Prior Strain on Damping Capacity and Mechanical Property during Heat Treatment
Authors: Kwak Juho , Kang Chang Yong , Kwon Han Sang , Kim Kwon Hoo
Published: November 2016

In previous study, it was investigated damping capacity on various deformation and heat treatment conditions in order to study damping capacity that was influenced by grain size and dislocation motion in detail. Magnesium alloy AZ31 was rolled at 673K with different rolling reduction, respectively. Specimens were machined out parallel to the rolled direction and annealed on various temperature and time. Then, damping capacity, microstructure and hardness was measured at room temperature. Factors affected on damping capacity are grain size, crystal orientation, dislocation motion, and so on. It was found that damping capacity has been affected by grain size and crystal orientation. Grain size and hardness is not examined obvious difference after annealing. In large prior strain, however, low damping capacity is appeared and damping capacity increases with increasing of heat treatment temperature. The reason is that resolved shear stress factor is influenced by damping capacity.
Welding of Automotive Aluminum Alloys by Laser Wobbling Processing
Authors: Barbieri Giuseppe , Cognini Francesco , Moncada Massimo , Rinaldi Antonio , Lapi Gabriele
Published: November 2016

The scope of this paper is to examine the improvement from laser welding by an innovative beam wobbling head towards the welding of tailored blanks parts, widely used in automotive to develop different stiffness aluminum components. For this purpose, butt joints and overlapping joints were produced from sheets made out of two industrial grades, i.e. AA-6082 T6 and AA-5754 H111 of different thickness. The technique was evaluated both with and without the use of a filler wire (AA-5556). The qualification of the welding process encompassed Non Destructive Testing (NDT) and mechanical testing. The results indicate that butt joints tend to fail within the base material (BM) of sheet with smaller thickness. On the contrary, the shear tests on lap joints highlighted a rupture mode occurring in the heat affected zone (HAZ) of the thin sheet. Remarkably, the wobbling process generally allows avoiding porosity when combined with an optimized set of welding parameters. Yet, a residual porosity was always detected in lap joints, varying with the size of the fused zone.
Mechanical Behavior of a Metal Matrix Nanocomposite Synthesized by High-Pressure Torsion via Diffusion Bonding
Authors: Lee Han Joo , Han Jae Kyung , Ahn Byung Min , Kawasaki Megumi , Langdon Terence G.
Published: November 2016

High-pressure torsion (HPT) is one of the major severe plastic deformation (SPD) procedures where disk metals generally achieve exceptional grain refinement at ambient temperatures. HPT has been applied for the consolidation of metallic powders and bonding of machining chips whereas very limited reports examined the application of HPT for the fabrication of nanocomposites. An investigation was initiated to evaluate the potential for the formation of a metal matrix nanocomposite (MMNC) by processing two commercial metal disks of Al-1050 and ZK60 magnesium alloy through HPT at room temperature. Evolutions in microstructure and mechanical properties including hardness and plasticity were examined in the processed disks with increasing numbers of HPT turns up to 5. This study demonstrates the promising possibility for using HPT to fabricate a wide range of hybrid MMNCs from simple metals.
Development of High-Temperature Shape Memory Alloys above 673 K
Authors: Yamabe-Mitarai Yoko
Published: November 2016

TiPd was investigated as a candidate of high-temperature shape memory alloys. To improve shape recovery, solid-solution hardening by addition of alloying element has been performed. The effect of alloying on martensite transformation temperature, shape memory effect, and yield strength of martensite and austenite phases were investigated. Zr and Hf were found to be effective element to improve shape memory effect. The most important factor to improve shape memory effect of TiPd is temperature to form Ti2Pd3 precipitates rather than strengthening.
The Study of the Microstructure of the Metal after Rolling Thick Workpieces of Nonferrous Metals and Alloys in Relief and Smooth Rolls
Authors: Lezhnev Sergey , Naizabekov Abdrakhman B. , Panin Evgeniy , Mazur Igor
Published: November 2016

One of the ways to improve the quality of steel production by rolling is the creation of additional streams of the metal flow, i.e. intensification of shear deformation not only in longitudinal but also in transverse direction. From the review of scientific-technical and patent literature it is known that to improve the quality of products when rolling usually use a system of alternating projections and depressions, which is created on the surface of the wide faces of slab or on work rolls. In this case, along with deformation in altitudinal and longitudinal directions, the conditions for deformation of the metal in the transverse direction, which has a positive effect on reducing the anisotropy of properties. Knowing the advantages of rolling with additional shear deformations, we have developed energy-saving technology of plate billets rolling of non-ferrous metals and alloys, allowing to obtain a uniform fine-grained structure throughout the volume of the workpiece, and designed two new constructions of the pair of work rolls with embossed surface as an annular groove, forming a trapezoidal protrusions and depressions alternating each other along the entire length of the barrel (the first pair to unequal treatment of the ledge to the depression and the second pair with equal respect to the ledge to the depression) to implement this technology in practice. In this paper were described results of investigations of microstructure evolution of copper alloys by rolling on the proposed technology in the relief rolls and according to the current technology in smooth rolls.
Morphology Evolution of Grain Boundary Carbides in Highly Twinned Inconel Alloy 600
Authors: Li Hui , Ma Jiao Rong , Liu Xin Rong , Xia Shuang , Liu Wen Qing , Zhou Bang Xin
Published: November 2016

The effects of grain boundary characters on the morphology evolution of grain boundary carbides in Inconel Alloy 600 with high proportional low Σ coincidence site lattice (CSL) boundaries aged at 715 oC for 1-100 h were investigated by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). During the aging process, the carbides precipitated at coherent twin (Σ3) boundaries are very few and finest within all the aging time. Bar like carbides precipitated near both sides of the incoherent twin (Σ3) boundaries, and bigger carbides than that of coherent Σ3 boundaries had been found on the incoherent Σ3 boundaries. Bar like carbides precipitated near only one side of Σ9 boundaries, and much bigger carbides than that of Σ3 boundaries have been found on the Σ9 boundaries. The morphology of carbides precipitated at Σ27 and random grain boundaries are similar, and is bigger than that of precipitated at other grain boundaries. The carbides precipitated at grain boundaries with all types grow bigger with the aging time prolonging, but their growth rates are different.
Deep Ultraviolet Photodetector Based on Sulphur-Doped Cubic Boron Nitride Thin Film
Authors: Li Yu Bo , Zhong Jian Wei , Zhou Li Ming , Sun Chao Lun , Wang Xiao , Yang Hang Sheng , Milne William
Published: November 2016

Cubic boron nitride (c-BN) is a wide bandgap III-V compound semiconductor potentially useful for solar-blind photodetectors. This paper describes work on the use of Sulphur doping to adjust the bandgap of c-BN films prepared by plasma-enhanced chemical vapor deposition (PECVD). An S-doped c-BN film based metal-semiconductor-metal (MSM) solar-blind ultraviolet (SBUV) photodetector was successfully fabricated and its electro-optical properties were characterized. The photocurrent shows peak responsivity at 254nm with sharp cutoff wavelengths at 220 and 300 nm, respectively, which is appropriate for use in solar-blind detection. The maximum response reached 1.55×10-7 A/W/cm2 with a rejection ratio of more than three orders of magnitude. The high solar-blind region UV response could be attributed to the successful substitution of boron by Sulphur and the suppression of B vacancies. The experimental results show the same peak in response at around 254nm as is found in the theoretical analysis.
Influence of Cu Doping on Martensitic and Magnetic Transitions in Ni-Mn-Sn Alloys
Authors: Li Zong Bin , Yang Bo , Zhang Yu Dong , Esling Claude , Zhao Xiang , Zuo Liang
Published: November 2016

In this work, the fourth element Cu was introduced to substitute Ni in polycrystalline Ni-Mn-Sn alloys. It was shown that Cu doping did not change the crystal structure of the martensite in Ni50-xCuxMn39Sn11 (x=0, 1, ......,7) alloys, but resulted in the decrease of martensitic transformation temperatures. Due to the higher atomic radius of Cu with respect to that of Ni, the lattice volume of martensite unit cell increases with the gradual substitution of Ni by Cu. For the alloys with the Cu content of 0-4%, the martensitic transformation is from weak magnetic (paramagnetic) austenite to weak magnetic (paramagnetic) martensite. When the Cu content is higher than 4%, the paramagnetic to ferromagnetic transition of austenite was introduced. The temperature interval between magnetic transition and structural transformation was enlarged with the increase of Cu content. Due to the relatively smaller magnetization difference between austenite and martensite, the field induced inverse martensitic transformation behavior is not significant in the present Cu-doped alloys.
Quasi-Static and Dynamic Properties of Ti-3.5Al-2.5V-1.5Fe-0.25O Titanium Alloy Plates
Authors: Liu Rui , Hui Song Xiao , Ye Wen Jun , Chen Rong , Yu Yang , Song Xiao Yun , Fu Yan Yan
Published: November 2016

This paper aimed to study the quasi-static and dynamic properties of a titanium alloy plate with nominal composition Ti-3.5Al-2.5V-1.5Fe-0.25O (ATI 425TM titanium alloy with lower limit of Al element) in thickness of 8 mm. The quasi-static tensile properties were investigated by MTSTM testing system at strain rate of 10-3 s-1, while dynamic compression properties by Split Hopkinson Pressure Bar system at strain rate of 3000±200 s-1. The results show that the quasi-static prperties of the Ti-3.5Al-2.5V-1.5Fe-0.25O plate are comparable to the commercial Ti-6Al-4V plate in 8mm-thick. The Ti-3.5Al-2.5V-1.5Fe-0.25O plate exhibats good dynamic strength. The average dynamic flow stress is 100MPa higher than that of Ti-6Al-4V plate. However, the maximum strain during homogeneous plastic deformation of Ti-3.5Al-2.5V-1.5Fe-0.25O plate is only 50~60% of that of Ti-6Al-4V plate.
Investigations on Hot Tearing Susceptibility and its Mechanism of Mg-Zn-Y Alloys
Authors: Liu Zheng , Liu Li , Zhang Si Bo , Wang Zhi , Mao Ping Li , Wang Yue
Published: November 2016

Hot tearing sensitivity of MgZn2.5YxZr0.5(x=0.5,1,2,4,6) alloys were predicted by using thermodynamic calculations based on Clyne-Davies’ model, and verified experimentally by using a "T"-type hot tearing permanent-mold equipment. The hot tearing mechanism with different Y content of MgZn2.5YxZr0.5 alloys was investigated. The results demonstrated that the predicted values are consistent with that of measured values. The hot tearing susceptibility of the alloys from high to low are: MgZn2.5Y2Zr0.5 > MgZn2.5Y0.5Zr0.5 > MgZn2.5Y4Zr0.5 > MgZn2.5Y1Zr0.5 > MgZn2.5Y6Zr0.5. Among the studied alloys, the hot tearing sensitive of the alloys of MgZn2.5Y1Zr0.5 and MgZn2.5Y6Zr0.5 is less than that of the commercial alloy AZ91.
Macrosegregation of Alloying Elements in Hot Top of Large Size High Strength Steel Ingot
Authors: Loucif Abdelhalim , Shahriari Davood , Zhang Chunping , Jahazi Mohammad , Lapierre-Boire Louis Philippe , Tremblay Rami
Published: November 2016

The chemical heterogeneities of alloying elements were evaluated in the hot top plus the top of a 40-ton ingot of as-cast high strength low alloy steel. The chemical compositions of small samples, taken from a slice cut along the longitudinal axis of the ingot, were obtained using mass spectroscopy. The chemical results were used to construct the chemical heterogeneity maps of C, Mn, Ni, Cr and Mo in the entire slice. The analyses of the different maps indicate the existence of positive segregation for all segregated elements except Ni where no segregation was observed. The most important macrosegregation was revealed in the centerline of the ingot. Carbon presents the highest degree of segregation whereas Mo presents the lowest one. In term of homogeneity degrees, Mn, Ni, Cr and Mo present better homogeneity than C whether in the top of the ingot or in the hot top.
Preparation and Squeeze Casting of Nano-SiCP/A356 Composite Assisted with Ultrasonic Vibration Process
Authors: Lü Shu Lin , Xiao Pan , Wu Shu Sen , Fang Xiao Gang
Published: November 2016

Metal matrix nanocomposites (MMNCs) have excited great interest in recent years, due to their very good properties. In this work, an efficient process by combining high-energy ball milling (HBM) with ultrasonic vibration (UV) was employed to prepare MMNCs. The composite granules containing nanoSiCP were produced by milling the nanoSiC and Al powders, and then were remelted in the matrix melt and treated by UV to prepare MMNCs. The MMNCs were finally formed by squeeze casting. The results indicate that globular nanoSiCP/Al compound granules with diameters between 1.5-2mm are obtained by dry HBM, and the nanoSiC particles are uniformly distributed in the granules. After remelting, nanoSiC particles in compound granules release in the matrix melt and are uniformly dispersed by UV within 2min. In MMNCs, nanoSiC particles concentrate mainly around eutectic phases, but no agglomeration is observed. The tensile strength of the MMNCs with 1wt.% nanoSiCP is increased by 19%, compared to the matrix A356 alloy.
Development and Research of Low-Cost Titanium Alloys, Especially Case of Japan
Authors: Ikeda Masahiko , Ueda Masato
Published: November 2016

Titanium (Ti) exhibits many attractive properties that enable practical applications. It is also considered to be a ubiquitous element, since it has the ninth highest Clarke number among all the elements. However, the principal beta-stabilizing elements for Ti, molybdenum and vanadium, can be very expensive, and so many Ti alloys are also costly. For this reason, less expensive alloying elements would be preferable. Iron (Fe) and manganese (Mn) are beta stabilizers for Ti alloys that are readily available, since they have the fourth and eleventh highest Clarke numbers, respectively. Furthermore, since Fe has a large diffusion coefficient in the beta phase of Ti, precipitation of the omega phase occurs more quickly when Fe is added. The behaviors of Ti-Mn and Mn-Fe alloys during heat treatment have been investigated and it has been found that, in some alloys, the isothermal omega phase is precipitated. Because this phase can lead to brittleness of the alloy, it is very important to suppress its precipitation. Since it is well known that aluminum (Al) suppresses isothermal omega precipitation, the present work investigated the effects of Al content on the phase constitution and heat treatment behavior of Ti-8.5 mass%Mn-1 mass%Fe-0, 1.5, 3.0 and 4.5 mass%Al alloys using electrical resistivity, Vickers hardness, and X-ray diffraction measurements. In the case of each of these alloys, whether solution-treated or water-quenched, only the beta phase was identified. The resistivities at room and liquid nitrogen temperatures were found to increase monotonically with Al content, while the Vickers hardness decreased up to 3 mass% Al and then remained constant. The addition of Al was found to suppress omega precipitation.
Enabling Diamond Deposition with Cold Spray through the Coated Particle Method
Authors: Aldwell Barry , Trimble Daniel , Yin Shuo , Lupoi Rocco
Published: November 2016

This paper describes the application of Cold Spray to the deposition of a diamond grade pre-coated with Cu and Ni. Diamond powders are therefore used as the sole feedstock without the addition of separate binders (ductile phases) in cold spraying. The experimental results showed that it was possible to manufacture thick metal-diamond composite coatings with high diamond fraction in the coating but without phase change or graphitization. Results presented in this paper demonstrate the feasibility of a new methodology for the deposition of metal-diamond/ceramic composite coating with the cold spray technique.
Thermal Desorption Spectroscopy Study on the Hydrogen Behavior in a Plasma-Charged Aluminum
Authors: Manaka Toshiaki , Aoki Masaya , Itoh Goroh
Published: November 2016

Hydrogen in aluminum has been known to be the cause of blister and pore. Some aluminum alloy is susceptible to stress corrosion cracking, which is based on intergranular cracking arisen from hydrogen embrittlement. The behavior of hydrogen in aluminum has not been fully understood yet. Hydrogen gas plasma enables to introduce high hydrogen concentrations into specimen without Al (OH)3 layer on the surface of specimen. In this paper, we have investigated the behavior of hydrogen in a plasma charged aluminum by means of thermal desorption spectroscopy, a method to evaluate the amount and trap states of hydrogen. Cold-rolled pure aluminum were annealed, electro-polished and charged with hydrogen gas plasma. Immediately after hydrogen gas plasma charging, TDS tests were performed under ultra-high vacuum. The hydrogen desorption spectrums obtained by TDS tests had three peaks corresponding to the co-diffusion of hydrogen-vacancy pair, dislocation and pore. Compared to a sample without charging, in a plasma charged sample, the amount of hydrogen trapped in vacancies especially increased.
Characterization and Modelling of the Microstructure and Texture Evolution in AlMgSi-Extrusions
Authors: Zhang Kai , Marthinsen Knut , Holmedal Bjørn , Friis Jesper , Pettersen Tanja , Segatori Antonio
Published: November 2016

The properties and surface appearance of aluminium extrusion are critically dependent on the microstructure and texture of the extruded profiles, and the requirements with respect to these aspects may vary with applications. Moreover it is often a challenge to produce extrusions with a consistent and homogenous grain structure and texture along as well as through the cross section of the profiles. It is thus vital to understand and be able to predict (model) how different microstructures and textures are formed and how they evolve during and after extrusion. In the present work a model framework has been implemented which includes a FEM model to account for the strain, strain rate and temperature along a set of particle paths during extrusion. From these the deformation texture and grain structure are calculated with an appropriate deformation texture model and a sub-structure evolution model, respectively. The sub-structure model have in the present work been coupled to a crystal plasticity model to provide an orientation dependent subgrain size and dislocation density during deformation which provides the driving force for the post-extrusion recovery and possible recrystallization behaviour. The post-extrusion microstructure and texture evolution is calculated with a recovery and recrystallization model, which is accompanied by a recrystallization texture model. The framework and its constituent models and their interplay are presented, and some preliminary results when applying this modelling framework to Al-Mg-Si extrusions are presented and discussed in view of corresponding experimental results.
Oxidation of Fe-Al Alloys (5-40 at.% Al) at 700 and 900 °C
Authors: Marx Vera , Palm Martin
Published: November 2016

Fe-Al alloys with Al contents between 5 and 40 at.% Al were oxidised for 1000 h in synthetic air at 700 and 900 °C to determine their oxidation behaviour. The minimum Al content which is necessary for the formation of protective Al2O3 scales decreases with increasing temperature from about 17 at.% Al at 700 °C to about 12 at.% Al at 900 °C. Established parabolic rate constants for the steady state growth of Al2O3 indicate formation of γ-Al2O3 at 700 °C while at 900 °C α-Al2O3 + Θ-Al2O3 scales form. At lower Al contents scales are predominantly formed by Fe2O3 as revealed by GI-XRD. It is also found that the oxidation behaviour is independent of the crystallographic order of the alloys, i.e. whether they are disordered A2 or ordered B2.
Technical Challenges in Narrow-Gap Root Pass Welding during Tandem and Hybrid Laser-Arc Welding of a Thick Martensitic Stainless Steel
Authors: Mirakhorli F. , Cao X. , Pham X.T. , Wanjara Priti , Fihey J.L.
Published: November 2016

As part of a collaborative program to develop advanced manufacturing processes for next-generation hydraulic turbines, this study investigated the technological challenges for joining 25-mm thick martensitic stainless steel (MSS) plates using tandem and hybrid laser-arc welding. Although candidate materials for the intended application typically include wrought AISI 415 and cast CA6NM, a martensitic 410 stainless steel (SS) was especially selected in this study due to its greater crack sensitivity. A narrow-gap groove was designed to minimize the amount of 410NiMo filler metal required to fill the groove using a multi-pass single-sided welding technique. All the welding trials were performed using a 5.2 kW fiber laser. The root-pass quality was characterized in terms of weld bead geometry, defects and microstructure. The main technical challenges observed for the root pass were lack of penetration, lack of fusion and cracking, as detailed in this work.
Crystallographic Investigation of the Initial Solidification Grain Structure in Al-Si Alloy
Authors: Morishita Hironori , Esaka Hisao , Shinozuka Kei
Published: November 2016

As-solidified structure of an ingot is composed of the chill, columnar and equiaxed zones. The whole solidified structure is strongly affected by the chill crystals. Some initial solidification grains have been observed on the ingot surface and thought to be traces of the nucleation point. The aim of this study is, therefore, to develop the experiment technique to make one ‘grain’ and to crystallographically investigate the initial solidification grain using EBSD analysis. In order to start solidification at a very specified position, a small metallic protrusion was installed on an insulating plate. Al-6 wt%Si alloy was melted at 800 °C and was poured on the metallic protrusion. In this study, the amount of protrusion was varied to investigate the growth mechanism of the initial solidification grain. The longitudinal cross section of the specimen was observed by an optical microscope, a scanning electron microscope. The starting position of solidification was the area that was on the metallic protrusion. In this initial solidification grain, it was difficult to observe the dendritic structure. The shape of this grain was about hemispherical. The grain area seemed to increase with increasing the amount of protrusion. The results of EBSD analysis showed that almost all initial solidification grains were composed by several crystals. The reason of this is that the nucleation frequency may increase with the amount of protrusion. The dendrite grew radially from the initial solidification grain continuously. The crystallographic structure was also continuous on the boundary of the initial solidification grain.
Magnetic Shape Memory - Polymer Hybrids
Authors: Aaltio Ilkka , Nilsén Frans , Lehtonen Joonas , Ge Yan Ling , Spoljaric Steven , Seppälä Jukka , Hannula Simo Pekka
Published: November 2016

Martensitic Ni-Mn-Ga based alloys are known for the Magnetic Shape Memory (MSM) effect, which upon application of an external magnetic field can generate a strain up to 12 % depending on the microstructure of the martensite. The MSM effect occurs by rearrangement of the martensite variants, which is most advantageous in single crystals. Single crystals are, however, rather tedious to produce and there has been attempts to achieve MSM effect in polycrystals. However, in polycrystals the magnetic field induced shape change remains low as compared to single crystals. As an alternative to the former, hybrid MSM materials offer several advantages. When compared to single crystals, hybrids have extended freedom of shaping, lower raw material price, relatively large MSM strain and easier manufacturability. Embedding MSM particles into a suitable polymer matrix results in actuation function or good vibration damping performance. In the present study we report on the mechanical, structural and magnetic properties of MSM polymer hybrids, which are prepared by mixing gas-atomized Ni-Mn-Ga MSM powder into epoxy matrix and aligning the magnetic particles in a magnetic field.
Development of a New Powder/Solid Composite for Biomimic Implant Materials by Electron-Beam Additive Manufacturing
Authors: Nakano Takayoshi , Fukuda Hidetsugu , Takahashi Hiroyuki
Published: November 2016

We proposed a new biomaterial composed of solid and powder cubic compartments to exhibit isotropic or bone-mimic one-dimensional anisotropic mechanical properties. The raw material used was gas-atomized Ti-6Al-4V ELI powder comprising spherical particles with a diameter of approximately 80 μm. Cube-shaped products composed of 27 (3 × 3 × 3) unit cubic compartments occupied by solid or powder part were designed using three-dimensional CAD. The products were fabricated by electron beam melting (EBM) (Arcam AB, Sweden) according to the specifications shown in a CAD drawing. The residual unmelted powder in the products does not need to be removed to make the products more mechanically integrated. Moreover, the layout of the powder and solid compartments in the products were arranged to achieve isotropy resembling a face-centered cubic atomic arrangement or a long-bone-mimic mechanical anisotropy with square prismatic columns. The products demonstrate isotropic or anisotropic Young’s modulus, yield stress, and toughness, all of which can be changed by CAD design and EBM. In conclusion, novel powder/solid materials comprising solid cubic parts and functionalized powder particles between them were successfully developed, which could be useful in biomedical and industrial applications.
Metal Matrix Composites as Environment-Friendly Protective Coatings
Authors: Bernasconi Roberto , Tucci Alessandro , Magagnin Luca , Nobili Luca
Published: November 2016

Protective coatings able to provide improved tribological behavior and corrosion resistance are demanded in many industrial applications. Although hard chrome is a very effective solution and is widely used, environmental issues related to hexavalent chromium push to develop alternative treatments.
Within the framework of the HardAlt European Project, electrodeposited composite coatings have been developed and main results of this investigation are reported in this work. Boron carbide micro-particles were dispersed in a Ni-P matrix under different operating conditions, in order to produce coatings with different composition and particle content. Structural and morphological characterization was performed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties were evaluated by micro-indentation and the tribological performance was assessed by block-on-ring tests. Electrochemical experiments were carried out to examine the corrosion behavior of the composite coatings.
Interesting results were obtained for composite coatings as regards hardness values, tribological behavior and corrosion resistance, even though some improvements can be realized. However, the results presented in this work show that composite coatings may represent a promising alternative to hard chrome for selected applications and also suggestions for further investigation are gained.
Hardness Homogeneity in an AZ80 Magnesium Alloy Processed by High-Pressure Torsion
Authors: Alsubaie Saad A. , Huang Yi , Langdon Terence G.
Published: November 2016

Experiments were conducted on an AZ80 magnesium alloy by processing by high-pressure torsion (HPT) at room temperature (296 K) for up to 10 turns under an imposed pressure of 6.0 GPa. Measurements of the Vickers microhardness along diameters and through the disk thicknesses were recorded after HPT to evaluate the evolution towards homogeneity. The results show hardness increases up to a factor of approximately 2 and the deformation is more homogeneous along the disc diameter than through the thickness.
Iron-Water Interface under Electrochemical Condition
Authors: Nunomura Norio , Sunada Satoshi
Published: November 2016

Spin polarized density functional theory calculations have been performed to characterize the structure of water molecules on iron surface under applied charges. It is found that water molecules of the contact layer take H-down configuration under the negative charge, on the other hand, under the positive charge, they adsorbed on a top site of iron atom, as the applied charge increases, the dissociation of water molecules proceed. In addition, we found that the energy shift of the Fermi level varies linearly in the range from-e to +e, while beyond this range it tends to saturate.
Evolution of Microstructure and Mechanical Properties with Different Partitioning Conditions of Q&P Steels
Authors: Arlazarov Artem , Ollat Melanie , Masse Jean Philippe , Bouzat Magalie
Published: November 2016

Q&P annealing cycles with different partitioning conditions were performed on cold rolled 0.2C-2.22Mn-1.44Si-0.21Cr steel. An important influence of partitioning temperature and time on the evolution of retained austenite fraction was shown through the saturation magnetization measurements. Such effect of partitioning conditions was also observed on the evolution of mechanical behavior. The evolution of microstructure and mechanical properties with the partitioning conditions was analyzed. Mechanical stability of retained austenite as a function of partitioning time was also assessed. Finally, modeling of the obtained stress-strain curves was performed and some explanations of the observed tendencies between partitioning conditions and tensile properties were proposed.
Microstructure Evolution and Deformation Mechanisms of Harmonic Structure Designed Materials
Authors: Ameyama Kei , Vajpai Sanjay Kumar , Ota Mie
Published: November 2016

This paper presents the novel microstructure design, called Harmonic Structure, which gives structural metallic materials outstanding mechanical properties through an innovative powder metallurgy process. Homogeneous and ultra-fine grain (UFG) structure enables the materials high strength. However, such a “Homo-“ and “UFG” microstructure does not, usually, satisfy the need to be both strong and ductile, due to the plastic instability in the early stage of the deformation. As opposed to such a “Homo-and UFG“ microstructure, “Harmonic Structure” has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro-but homogeneous on macro-scales. In the present work, the harmonic structure design has been applied to pure metals and alloys via a powder metallurgy route consisting of controlled severe plastic deformation of the corresponding powders by mechanical milling or high pressure gas milling, and subsequent consolidation by SPS. At a macro-scale, the harmonic structure materials exhibited superior combination of strength and ductility as compared to their homogeneous microstructure counterparts. This behavior was essentially related to the ability of the harmonic structure to promote the uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability.
Modeling and Simulation of Q&P Steels
Authors: Paul Georg , Thiessen Richard G.
Published: November 2016

Two important objectives of the automotive industry are the decrease of the body-in-white weight and the improvement of the passenger safety. High strength steels (HSS) are widely used to achieve these objectives. Quenching and partitioning (Q&P) has recently been proposed to achieve high strength steel grades for the third generation of advanced high strength steels (AHSS), which contain a considerable amount of retained austenite. Due to their microstructure these new steel grades combine a high tensile strength with good elongation values, as long as cementite precipitation is avoided. A model describing the involved phase transformations is presented. Special focus is put on the cementite precipitation and how it is influenced by silicon and aluminum additions.
A Comparative Study of Molecular Motion Cooperativity in Polymeric and Metallic Glass-Forming Liquids
Authors: Aniya Masaru , Ikeda Masahiro , Sahara
Published: November 2016

In order to investigate the relationship between the bonding nature and the cooperative relaxation, a comparative study of the relaxation behavior in polymeric and metallic glass forming systems has been performed based on the Bond Strength–Coordination Number Fluctuation (BSCNF) model developed by the authors. In the present work, we studied the correlations between the fragility m, the Vogel temperature T0, the degree of molecular cooperativity NB, and the Kohlrausch exponent βKWW. The results show that T0 and NB increase, whereas βKWW decreases systematically with the increase of m. Reflecting the difference of the interatomic interactions of the materials considered, the analysis by the present study reveals that the value of NB in ion-conducing polymers is about 5 times larger than that in metallic systems, and for each system, the material dependence of βKWW is clearly seen in the fragility index m and the cooperativity NB.
Anti-Bacterial Nanocomposites by Silver Nano-Coating Fragmentation
Authors: Quadrini Fabrizio , Bellisario Denise , Santo Loredana , Tedde Giovanni Matteo
Published: November 2016

Silver nanocomposites are of great interest for several fields, ranging from packaging to biomedical applications, because of their known antibacterial properties. However, their use is strongly limited by technological issues: synthesis methods of silver nanoparticles are still difficult to control in terms of size, shape and aggregation. Moreover separation of nanoparticle aggregates should occur during part manufacturing by mixing with the polymer base but this process is also troublesome. In the present study, a new process to fabricate silver nanocomposites with antibacterial properties is presented. Silver nanofilms are deposited by radio frequency (RF) sputtering on polypropylene (PP) substrates. Consequently PP coated substrates are cut and inserted in a small-scale polymer mixer to produce the nanocomposite in a single step, without the need of producing nanoparticles. In fact, nanoparticles originate by the fragmentation of the nanocoating. Microscopic observations of nanocomposites revealed silver nanoclusters of different sizes. Their antibacterial activity has been verified in accordance to ISO 22196. The antibacterial activity of the nanocomposite was detected for the Escherichia coli and Staphylococcus aureus bacteria.
Damage Initiation in Dual-Phase Steels: Influence of Crystallographic and Morphological Parameters
Authors: Archie Fady , Li Xiao Long , Zaefferer Stefan
Published: November 2016

Typical microstructures of dual-phase (DP) steels consist of hard martensite particles dispersed within a ductile ferritic matrix. These microstructures possess a complex network of grain and interphase boundaries, which, together with the mechanical contrast of their phase composition, control micro-damage initiation mechanisms, induced by deformation. Accordingly, in this study we analyze the influence of individual microstructural features and interfaces on damage nucleation and progression in DP steels with respect to applied tensile strain. Prominent micro-damage mechanisms include cracking of martensite and damage initiation at interphase boundaries. Influence of martensite morphology is discussed based on a statistical analysis of the damage features as observed by electron channeling contrast imaging (ECCI) and electron backscatter diffraction (EBSD) maps. Prior austenite grain boundaries (PAGbs) in martensite show a brittle behavior and are highly susceptible to crack propagation.