bluuebunny/crossref_metadata_2025 huggingface dataset:
Eccentric connectivity index of identity graph of cyclic group and finite commutative ring with unity
Authors: Abdussakir A , Puspitasari L A , Irawan W H , Alisah E
Published: November 2019

Research on graph associated with a finite algebraic structure has attracted many attentions. On the other hand, eccentric connectivity index is an interesting topic and many studies have been reported. For simple connected graphG, lete(v) denoted the eccentricity of vertexvanddeg(v) denoted the degree of vertexvinG. Eccentric connectivity index ofGis defined as the sum of alle(v)deg(v), for anyvinG. We focus the study on determining eccentricity connectivity index of identity graph of cyclic group and finite commutative ring with unity. We present the exact formula for eccentricity connectivity index of identity graph of these two algebraic structures.
Representation of completion of fraction calculations for class V students
Authors: Farida N , Ferdiani R D
Published: November 2019

This study aims to: (1) To determine the extent to which students understand and solve fractions, (2) Errors that students often do in solving fractions. The method in this study is through direct qualitative research by observing the object of research on understanding the problem solving fractions. While the object in this study is how to represent the completion of count operations on fractions. The results obtained in this study are: (1) the value of problem solving ability in fraction count operations ranges from 0 to 100 with an average of 48.42 students understand how the process of completing the fraction count operation. (2) types of errors made by students in completing fraction counting operations include students not yet understanding the concepts of addition, subtraction, multiplication, and division of compute operations on fractions, underprivileged students in systematic steps to complete counting operations on fractions, and students inaccurate in doing calculations. So that from this research should be designed a form of teaching that facilitates students in understanding the solution to fraction material.
Estimate model of total fertility rate based on effectiveness of contraception
Authors: Gunawan G , Kurniati E , Sukarsih I , Suhaedi D
Published: November 2019

In this paper we will show an indirect way of calculating fertility. Where this can determine the prevalent birth rate as an indicator of successful control of population through family planning program (KB). So The results of the research show that the higher the effectiveness of the use of contraceptives, the higher the number of preventable births resulting in the least possible birth rate, and this calculation can be determined total fertility rate based on the effectiveness of the use of contraceptives.
Derivative application in economic problems
Authors: Marsitin R , Sesanti N R
Published: November 2019

The objective of this research is to describe derivative applications in economic problems. This study uses quantitative descriptive approach. The study is conducted at the home industry of snack in Surabaya. The data collection in this research uses observation and documentation. The data analysis uses tabulation methods and derivative applications. The results of the study show that home industry of snack gains profit because the results of the second derivative are negative. The conclusion of the study that derivative applications in economic problems include four stages, the first stage is determining the variables, the second stage is determining the mathematical model, the third stage is completing the mathematical model and the fourth step is using the second derivative smaller than zero.
Limited trial on origami construction as mathematics learning strategy for early childhood on kindergarten teachers
Authors: Respitawulan R , Afrianti N
Published: November 2019

The aim of this study is to do a limited trial on the hypothetical learning strategy for early childhood mathematics concepts using origami construction. Using the training devices designed for the limited trial, 17 early childhood education teachers in Bandung and its surrounding areas were trained on the learning strategy. The trial pre-test and post-test scores and it shows an improvement in the knowledge of participating teachers of early childhood mathematics learning using origami. The significance of the improvement had been proven using t-paired test. The improvement might be caused by the fact that most of the participants only have high school diploma as education background with lack of training on early childhood mathematics learning, and also with the fact that origami is mainly used for fine motor skills improvement in early childhood education. Thus, the origami construction can be used as an alternative strategy to learn mathematics concept in early childhood.
Lesson study: Increasing mathematical critical thinking ability?
Authors: Ferdianto F , Ningrum N B
Published: November 2019

The aims of this paper is determine the increase of students critical thinking ability in the material system of two-variable linear equations using the problem based learning model based on lesson study. This research is a quantitative with the method of analysis using the analysis of N-Gain test on the results of the student’s problem description test. The sample taken in this study is purposive sampling which is used only one class. The results showed that there was an increase in the critical thinking ability using the problem based learning model based on lesson study as seen from the increase in the average critical thinking ability test results of 0.70 and included in the high criteria.
Exploring the distribution of time to failure of bearing experimental data
Authors: Darwis S , Hajarisman N , Suliadi S , Widodo A
Published: November 2019

Bearing failure degradation describes the probability of failure after survive a length of time. This paper explores the empirical distribution of time to failure and modeling of bearing failure degradation using vibrational experimental data. Kurtosis was used as a feature of vibrational data. The failure probability was estimated using actuarial method. Fitting to some time to failure distributions and bearing failure degradation models will be discussed as an illustration of the proposed method. The results of the study can be used to predict the percentage bearing failures for a certain time of period. The results of the proposed method can contribute to maintenance system of a mechanical system
Mechanical properties and corrosion resistance of grinding ball Fe-xMn-10Al-1.25C alloys
Authors: Kartikasari R , Wijaya A E , Iskandar A D , Subardi S , Triyono T
Published: November 2019

This research aims to determine mechanical properties of grinding ball Fe-xMn-10Al- 1.25C alloys. The grinding ball alloys were prepared by an induction furnace under argon atmosphere. Al and C levels, 10% and 1.25% respectively, in Fe-Al-Mn grinding ball were kept constant while Mn content was varied by 15%, 20% and 25%. Grinding ball of Fe-Cr-C alloy as a comparison was obtained from the cement industry. Mechanical properties were investigated using tensile testing machine, Vickers hardness testing machine, Charpy impact test machine, and wear testing machine. Corrosion resistance was investigated using weight loss method. The results showed that the best mechanical properties occurred at 25% Mn composition, which were superior to Fe-Cr-C grinding ball. The ultimate tensile strength (UTS), yield strength, and elongation of Fe-xMn-10Al-1.25C grinding balls were in the range of 1215-1435 MPa, 927-1135 MPa, and 40.74-57.72% respectively. The hardness of these alloys was in the range of 421-550 VHN, the Charpy impact of these alloys was in the range of 1.24-1.55 J/mm2, while wear resistance of these alloys was in the range of 0.0004-0.0007 gr/s. The mechanical properties of Fe-Cr-C grinding ball were 1125 MPa (tensile strength), 875 MPa (yield strength), 47.8% (elongation), 544 VHN, 0.45J/mm2 (toughness), and 0.0004 gr/s (wear resistance) respectively. The best corrosion resistance of Fe-5Al-xMn-1.25C and Fe-Cr-C grinding balls were 0.016 mm/yr and 0.035 mm/yr respectively.
Optimization of Silver Nanoparticles Synthesis using Kawista (Limonia Acidissima Groff.) leaves ethanol extract
Authors: Wisnuwardhani H A , Lukmayani Y , Hazar S , Hoeruniswah H
Published: November 2019

Nanotechnology is one of science technology that current interest due to their wide variety of application in fields. Nanoparticle has different characteristic from previous macroscopic characteristic before it is turned to Nano-size. This research aims to get the optimum condition to synthesize silver nanoparticle from ethanol extract of Kawista (Limonia acidissima Groff). Extraction was done by refluxs method. Different variation does the optimization of silver nanoparticle, i.e., with and without incubation, with and without stabilizer, with and without stir, and stirrer time variation. The optimum condition to synthesize silver nanoparticle was conducted based on characterization result from UV-Vis Spectrophotometric method, and particle size from particle size analyzer result. The optimum condition to synthesize silver nanoparticles was done using AgNO3: 1% ethanol extract = (10 :1), 5 hours of stirred and 15 hours of incubation time. Those silver nanoparticles are 130, 4 nm in particle size and 0,295 in polydispersity index. Per SEM characterization, silver nanoparticles have a rod and ellipse in shape.
Effect of solid lipid nanoparticles system on the stability of Green Tea leaves (Camellia sinensis L. Kuntze) extract as sunscreen
Authors: Aryani R , Hidayat A F , Darma G C E , Utami O
Published: November 2019

Green tea (Camellia sinensisL.) is known to have activity as antioxidant and sunscreen due to its catechin compound. The major catechin-derived compound is epigallocatechin gallate (EGCG). However, EGCG in green tea leaves is unstable due to its rapid degradation and large molecular mass of 458 daltons, making it difficult to penetrate the skin. The purpose of this research is to formulate solid lipid nanoparticles (SLN) of green tea leaves ethanol extract using high speed homogenization and sonication method, as well as to evaluate SLN ability in improving extract stability as sunscreen using UV-Vis spectrophotometry. SLN formula contained 0,1% green tea leaves ethanol extract, and the most optimal formula was composed of 4% lipid (Precirol ATO 5:Gelucire 44/14) 4:1 and 1% Kolliphor P188 as surfactant. Characterization results showed particle size of 286.7 nm, polydispersity index 0.296, and zeta potential -3.7 mV. Photostability test using 120-minutes irradiation showed decrease in percentage of DPPH free radicals damping at 5.34% extract and 1.77% SLN for UVA, and 7.7% extract and 2.34% SLN for UVB.
Analysis of seismic signal in order to determine subsurface characteristics
Authors: Ayu H D , Sarwanto S
Published: November 2019

The purpose of this study is to know how to analyze the seismic signals volcanic to determine subsurface characteristics. The method used to analyze seismic signals volcanic is Fast Fourier Transform. Sample signal seismic wave of this study come from Semeru Volcano and Ijen Volcano signal seismic based on seismogram. The first data are given by swarm and wvw software. Analyze seismic wave in this study proves the existence of a relationship between seismic attributes (frequency, amplitude, time (origin, primer dan secondary) and attenuation) of the characteristics of the earth's surface. This study proved there is the correlation between subsurface characteristics and energy, it shows by attenuation factor value (Q value). The value of factor Q indicates how many waves are absorbed by the medium.
Impact of using augmented reality applications in the educational environment
Authors: Annafi A , Hakim D L , Rohendi D
Published: November 2019

This study discusses a literature review that focuses on the use of Augmented Reality in the educational environment. The author reviews articles published in the last 10 years that discuss the use of Augmented Reality in learning media at all levels of education. A total of 30 articles were analyzed thoroughly. The result shows various types of research methods were found and the levels of education varied from early childhood education, elementary school, junior high school, senior high school, vocational school, and tertiary education, even the technology was also used for students with special needs (disability). The research designs found also varied such as Experiment, Analysis, Action Research, Surveys, Mixed Method, and Research-Based and Development. The most prominent role of Augemented Reality in educational environment is to increase students’ thinking ability, understanding, motivation, response, and learning outcomes towards the learning process. Most of the researches were conducted in secondary level while little attention was given in vocational level. Thus, this article would recommend to future studies to conduct more researches in vocational setting in order to display more evindence about the phenomenon of Augmented Reality in educational setting.
Exploration of the augmented reality model in learning
Authors: Afandi B , Kustiawan I , Herman N D
Published: November 2019

Augmented reality is a technology that integrates virtual content into real environments in the form of mobile and desktop. This technology has begun to be developed in various fields, even as a learning medium with various models. We are exploring augmented reality models that have been developed by reviewing several journals related to augmented reality. We have collected 100 journals from various data sources with augmented reality keywords. We select 41 journals and we find 5 augmented reality models, including 3D models, 3D simulations, 3D animations, video models, multimedia models. There are two types of augmented reality, using markers and without markers, for augmented reality using markers requires a marker as a trigger for the emergence of augmented reality objects into the real environment, while augmented reality without markers does not require markers to trigger the emergence of augmented reality into real environments.
The impact of E-learning on higher education perception, skills, critical thinking and satisfaction
Authors: Khan M L H , Setiawan A
Published: November 2019

E-learning was initially implied as an emotionally supportive network for separation learning and this is the reason e-learning is regularly called separate training, despite the fact that e-learning is a smaller idea. E-learning is utilized to convey preparing, training and cooperation utilizing different electronic media in any case, overwhelmingly, the Internet, whose apparatuses have comprised the principle driver of e-learning and e-Learning has impact on students’ perception, critical thinking and others factors. The review is intended to provide a summary and a critique of various e-learning research topics and methods. The 3-step review process was composed of articles searching and retrieval, filtering and sorting, and final inclusion. It was found that e-learning improved student perceptions, communication, quality of education, critical thinking, self-learning and the result also shows that the impact of teacher’s responsibility and students’ satisfaction in higher education.
Survey of use mobile augmented reality for teaching materials
Authors: Fadhil M , Sumardi K
Published: November 2019

This study discusses the review of the literature focuses on the use of Augmented Reality (AR) as a teaching material. Authors conducted a review 20 articles which were published from 2008 to 2018. Design studies also found a variety of experiments such as data, analysis, action research, surveys, mixed methods, and Research and Development. This review found that the use of AR as a teaching material in learning shows that the AR is able to improve your skills, understanding, motivation, response, and the results of student learning of the content and media used.
Green skills for electrical engineering students
Authors: Nurdiansyah N , Mulyanti B , Sucita T
Published: November 2019

Green skills are the knowledge, skills, abilities, values, and attitudes needed to develop and support efforts to reduce the impact of human activities on the environment for the realization of social, economic and survival. This study aims to identify green skills especially for electrical engineering students and why this is important. In this study literature studies were conducted with documents and articles sought in electronic databases such as Academia, Elsevier, Emeraldinsight, Google Scholar, ResearchGate, and ScienceDirect. The findings from the results of this literature study reveal that the importance of green skills for electrical engineering is inseparable because the demand for labor in the renewable energy sector reached 10.35 million in 2017, up 5.3% from the previous year and predicted to continue to rise in the following years. The ability such as renewable energy skill and energy efficiency skill are some of the green skills that are suitable for electrical engineering students. To developing green skills, require effort such as developing a curriculum that is oriented towards environmental sustainability and with the integration of environmental sustainability content through problem-based learning.
Sick building syndrome: Assessment of school building air quality
Authors: Vesitara R A K , Surahman U
Published: November 2019

Sick Building Syndrome is a term used to describe a situation in which occupants of a building have a symptoms and discomfort. Sick Building Syndrome The symptoms of SBS are shown in complaints that occur in occupants of the building as well as eye irritation, nonspecific symptoms, upper respiratory tract, lower respiratory tract, and skin irritation. SBS was also met on building buildings in schools which caused disruption of teaching and learning activities The method of this study used a literature review which conducted on journals published in the last 10 years with the aim of producing references that are more focused on the development of the latest problems and solutions. The result of this review show that SBS occur because an environment factor, thermal factor, and psychosocial. Overall, this review provides an appropriate reference for further research by the specific factors about SBS and further symptoms related to SBS affect student learning outcomes.
The dynamics of electronic cinema production to maintain rating
Authors: Paramita S
Published: November 2019

Electronic cinema or so-called sinetron is an important industry in private television in Indonesia. Without sinetron, private television will not be able to survive digital of era today. Although sinetron as a product of mass communications appear in era before it, in fact, sinetron can still survive until today. For that, the production house raced to create a sinetron story that is interesting to watch by the people of Indonesia. MNC Picture which is a subsidiary of MNC Group has produced sinetron, films and TV shows to support TV stations under MNC Group such as RCTI, MNC TV, Global TV, and others. Sinetron made by MNC Picture was able to grab the attention of Indonesian audiences, as evidenced by Sinetron able to become television program with the highest rating. It is interesting to examine in the study of communication science to find out how the dynamics of electronic cinema production to maintain the rating in MNC Picture. The theory used to approach the object is the political economy theory of communication and mass communication. The methodology used in the research is qualitative phenomenology. The result of this research is that there are three components of electronic cinema production dynamics to maintain the rating in MNC Picture which is sinetron theme and storyline which is close to Indonesian people habit, second monitoring of rating, and placement of digital product in sinetron content.
Online digital media in supporting product sales
Authors: Hamdan Y , Ratnasari A , Julia A
Published: November 2019

The phenomenon of online shopping is currently trending in the community, one of the supporting aspects because the convenience offered by online sellers can increase the enthusiasm of people to buy products. Business women follow this trend by using online digital media to support product sales. This study aims to analyze the use of online digital media including the most effective websites, Facebook and Instagram in increasing sales. Research informants were Indonesian Women Entrepreneurs Association (IWAPI) of West Java. Qualitative methods are used with a case study approach. Data collection is done by observation, interviews, and literature. The research findings found women entrepreneurs using websites, Facebook, and Instagram to market and support product sales. Among the three media, Instagram is the most used and most effective media in increasing sales. The benefits of using media are to inform and remind potential consumers and consumers of the products offered, in the form of photos and videos. The media support transactions with potential customers through the WhatsApp facility. The inhibiting factors for the use of media include women entrepreneurs who cannot fulfill the wishes of prospective consumers of product information quickly.
ICT (Information and Communications Technology) - based on social and emotional competence assessment
Authors: Hikmah H , Koeswantono S , Fridani L , Hapsari N M
Published: November 2019

The aim of this research is to develop an ICT-based on social and emotional competencies assessment that is practical and effective. The on line assessment application model that is developed in this study is an online assessment that utilizes information and communication technology with social-emotional assessment applications (Si Emo®). ICT-based assessment is an online assessment application based on information and communication technology. The online assessment development process includes the preparation of social-emotional assessments offline, then includes assessments to the server to be used online. The availability of supporting technology (both hardware and software) and readiness of human resources (HR) are needed for the development of this assessment. This study is a type of R & D (Research and Development) approach with a guideline development model. This research was conducted in PAUD institutions which involved early childhood educators in Jakarta. Data collection techniques were conducted through observation, interviews, and questionnaires. Data analysis techniques were carried out with descriptive analysis. The product feasibility testing stage was validated by experts, whereas alpha and beta tests was conducted by early childhood educators. The results obtained from this study are a set of social and emotional assessments application (Si Emo). The results showed that Si Emo application is valid, reliable and useful to assess children’s social and emotional competency. The implication of this research can be used as one of solutions for early childhood educators in assessing social-emotional aspects of children’s development.
Early warning system model as a resilience of disaster-prone communities
Authors: Rochim M , Bajari A , Damayanti N A , Bakti I
Published: November 2019

Living in a watershed (DAS) means getting ready for the risk of flooding. The choice of relocation is often taken by the government to reduce these risks. But the attachment of citizens to the surrounding environment makes relocation not the best choice. This study seeks to reveal how the Garda Caah community as citizens in the Citarum River Basin is able to decide and be responsible for their ideas, decisions and actions in the face of flooding. This study uses qualitative methods with a case study approach. The data collection techniques are carried out by interviews, focus group discussions and observations. The findings resulted resilience the communities around the Citarum watershed are realized by forming the Garda Caah Community, which in their work projects seeks to minimize the effects of flooding by sharing information about possible flooding. The Garda Caah community created a flood early warning system so that residents and local governments prepared to face flooding. Dissemination of information about floods is carried out through various media commonly used by the public, both traditional and modern channels.
ICT literacy level analysis of elementary school teachers
Authors: Latif M A , Abdullah A G , Hakim D L , Widiaty I , Islami A R , Zakaria D , Arasid W , Anggraeni A
Published: November 2019

The purpose of this study was to determine the level of Information and Communication Technology (ICT) literacy in the ability of elementary school teachers in integrating ICT in learning and knowing the factors that influence ICT literacy of teachers reviewed by age, gender and educational background. The method used is a quantitative descriptive approach with a longitudinal trend survey method, with data collection techniques using a questionnaire. The results of this study indicate that the level of ICT literacy of elementary school teachers which refers to the Ministry of Communication and Information of the Republic of Indonesia is at the level one of the six levels available. This means that an individual has had one or two experiences, where information is an important component for achieving desire and solving problems, and has involved information technology to look for it. Then based on inferential analysis the factors that influence the level of ICT literacy of elementary school teachers show that age and gender factors significantly influence the ICT literacy of teachers. While the education level factor does not have a significant influence on the level of ICT literacy of teachers. The results of this study can be a reference for improving the ability of elementary school teachers in ICT literacy.
Level of ICT literacy: The ability of elementary school teachers to use ICT investigation in Cimahi
Authors: Islami A R , Abdullah A G , Hakim D L , Widiaty I , Latif M A , Juhana A , Amelia N , Putra D E
Published: November 2019

This study aims to analyze the level of information and communication technology (ICT) literacy of elementary school teachers and determine the level of ICT literacy of elementary school teachers grouped by; gender and age. The number of participants in this study were 345 respondents spread across 3 sub-districts. The method used is a descriptive quantitative approach with data collection techniques using a questionnaire. Research shows that the level of ICT literacy of elementary school teachers is at level 2 of 6 levels, where teachers have repeatedly used ICTs to help with daily activities and have a pattern of repetition in their use. Based on gender and age, there was no significant difference between the ability of male and female teachers. Then when viewed by age shows a significant value between younger teachers and older teachers. Where the younger teacher's age has the higher level of ICT ability.
Thirty years of collaboration and research from 1989 to 2019: a tribute to Ruslan Z. Valiev
Authors: Langdon T G
Published: November 2019

A visit to the Institute of Problems of Superplasticity of Metals in Ufa in 1989 initiated a cooperation and collaboration with Ruslan Valiev that has continued for the last thirty years. This collaboration started with fundamental investigations of superplasticity, such as the demonstration that intragranular slip is necessary to accommodate grain boundary sliding in conventional superplastic flow, but it was then extended to cover the processing and properties of a wide range of metals produced using severe plastic deformation to achieve exceptional grain refinement. Highlights included the publication of a first comprehensive review of equal-channel angular pressing (now with more than 3600 citations on Google Scholar) and co-authoring a textbook (Bulk Nanostructured Materials: Fundamentals and Applications, published by TMS/Wiley in 2014).
Progress in NanoSPD research through scientometric analysis
Authors: Safargalina Z , Alexandrov I V
Published: November 2019

In this paper, we use the scientometric approach based on the Web of Science Core Collection to analyze the data on publication activity in the area of nanostructured materials processed by severe plastic deformation (SPD) techniques on the following three main topics: ultrafine-grained materials, severe plastic deformation and bulk nanostructured materials. The results marked early 1990s as the starting period for first publications in question as well as their fast development. Pioneer works by Prof. Valiev and his laboratory at that time and their role in the growth of nanoSPD-related research were outlined.
The influence of the mode of interaction of compact samples made of nonpassivated iron nanopowders with air on their microstructure
Authors: Alymov M I , Seplyarskii B S , Vadchenko S G , Kochetkov R A , Rubtsov N M , Zelensky V A , Schukin A S
Published: November 2019

In this work, various modes of interaction (spontaneous ignition or a combustion mode) of compact samples made from nonpassivated iron nanopowders with air are found out. The experiments showed that the modes of interaction of the samples with air after their extraction from a weighing bottle depended on the media (argon or air), in which the weighing bottle was placed before extraction of the samples, as well as on the duration of the exposure of the weighing bottle in the air. It is shown that the process of interaction of the sample with air has a surface character; the inner layer of the sample contains unreacted nanopowder. The microstructure of the transverse fracture of the samples after spontaneous ignition and combustion represents a porous aggregation of agglomerates. Integral energy-dispersive analysis showed a higher content of oxygen in the near-surface layer of the sample about 300÷500 microns thick. The analysis of the microstructure of the fracture of a separate agglomerate showed the presence of a layer with an elevated oxygen content on the surface of the agglomerates. Particles in the agglomerates retain the dimensions of passivated iron nanopowders.
Microstructure evolution in a CuZr alloy and CP Ti processed by a novel technique of free bending in rotating rollers
Authors: Janeček M , Krajňák T , Veselý J , Minárik P , Preisler D , Stráský J , Raab A G , Raab G I , Asfandiyarov R N
Published: November 2019

A novel technique referred to as free bending in rotating rollers was employed to refine the initial structure and to produce gradient fine-grained microstructures in the Cu0.5Zr alloy and commercially pure titanium (CP Ti). A newly designed die allowing a continuous and repetitive movement of a workpiece through a set of rollers in a channel bent by 90 degrees was employed to produce a series of billets after different numbers of passes resulting in different strains imposed on the billet. Microstructure evolution with increasing number of passes was characterized by precise measurements of microhardness (HV) distribution along the cross section of individual billets. The heterogeneous distribution of HV observed after a single pass was transformed to almost a uniform one in the whole cross section of the billets after 8 passes. EBSD analysis and TEM observations revealed a significant microstructure refinement in both materials after the final stage of processing. A homogeneous microstructure with an average grain size of about 300 nm was observed in CP Ti, whereas the microstructure of the Cu0.5Zr alloy was not fully refined and exhibited a bimodal grain size distribution. The experimental results were compared with the theoretical modelling of strain distribution by FEM.
The effect of heat treatment on the structure and mechanical properties of additively manufactured stainless steels
Authors: Korznikova G F , Smirnov V V , Gunderov D V , Mulyukov R R
Published: November 2019

Selective laser sintering was applied for stainless steel samples additive manufacturing. It was found that in the as fabricated state, the samples consist of martensite and residual austenite, contained significant dislocation density and residual stresses. Additively manufactured samples had an ultrafine-grained structure with predominantly high angle grain boundaries and were free of crystallographic texture and residual porosity. The ultimate tensile strength of the as-built steel was 960 MPa. Annealing caused a decrease in residual austenite, but did not significantly affect the size and morphology of the grains. The ultimate strength after annealing increased markedly while maintaining plasticity.
Effects of nano and submicrocrystalline states under a wide range of loads
Authors: Naimark O B
Published: November 2019

The scale in nanomechanics (10−10−10−9 m) has a fundamental physical meaning and can be considered as a control parameter when considering qualitative changes in the properties of polycrystalline materials when the grain structure changes in a wide range of load intensities. The existence of this parameter can lead to effects beyond the scale, which are traditionally considered in mechanics, and are accompanied by the influence of quantum effects on the deformation properties and failure of materials. New ideas about submicrocrystalline and nano-scale structure of materials achieved by the use of high-resolution methods (synchrotron tomography, soft X-rays, nanoindentation) have led to qualitative changes in approaches to the study and description of the properties of materials, including biomaterials. This may provide new information on the processes of deformation and fracture at the micro- and nano-scale level and lead to new approaches in the design and evaluation of the reliability.
Mechanical properties and thermal stability of an ultrafine-grained near β titanium alloy
Authors: Naydenkin E V , Mishin I P , Ratochka I V , Lykova O N
Published: November 2019

Comparative studies of the structure, mechanical properties and thermal stability of an ultrafine-grained near β titanium alloy of the transition class Ti-5Al-5Mo-5V-1Cr-1Fe obtained by the methods of multiple pressing and radial-shear rolling with subsequent aging have been carried out. It is shown that as a result of multiple pressing, the formation of a homogeneous micro-duplex ultrafine-grained structure with an average grain (phase) size of ∼0.2 μm is observed. Radial shear rolling followed by aging leads to the formation of an inhomogeneous structure with precipitates of the α phase particles and a subgrain size of the β phase of about 0.5 μm inside which thin-acicular precipitates of the metastable α” phase are observed. Despite the smaller imposed plastic deformation and the larger size of grain-subgrain structure, alloy samples after radial-shear rolling and aging demonstrate higher strength properties at room temperature compared to the alloy obtained by multiple pressing (the ultimate strength of the alloy after these treatments is 1695 and 1600 MPa, respectively.) At the same time, the alloy obtained by the method of multiple pressing shows higher ductility and thermal stability of the mechanical properties due to the micro-duplex ultrafine-grained structure. The drop in strength as a result of annealing is due to the development of recrystallization in the case of the alloy after pressing and the dissolution of the strengthening α” phase in the case of the alloy after radial-shear rolling and aging.
Effect of frequency on plasma electrolytic oxidation of zirconium in pulsed unipolar mode
Authors: Parfenov E V , Mukaeva V R , Farrakhov R G , Saikiran A , Hariprasad S , Manoj P , Lokesh E , Rameshbabu N
Published: November 2019

Using the method of in situ impedance spectroscopy, an optimization of plasma electrolytic oxidation (PEO) was performed, and the influence of the pulse frequency was evaluated for the coating of Zr-1Nb alloy. It was shown that the in situ impedance modulus decreased with increasing the pulse frequency in a pulsed unipolar mode. Also, the protective properties of the coating improved with frequency; this was attributed to the increase in the uniform distribution of the microdischarges over the sample surface. As a result, the optimal frequency range of PEO was justified based on the impedance spectroscopy studies.
Structure of materials ultrasonically consolidated from coarse-grained and nanostructured plates of commercially pure copper
Authors: Parkhimovich N Yu , Yusupova N R , Nazarov A A
Published: November 2019

Ultrasonic consolidation of commercially pure copper plates with coarse-grained and ultrafine grained structures was carried out. Copper plates in both states were joined by ultrasonic welding using the same route. Consolidated samples were studied in a cross section parallel to the oscillation direction. The compressive strain value and the joint quality in relation to the initial structure of the material were studied. It is shown that the ultrasonic consolidation is a promising method of additive manufacturing using bulk nanostructured materials.
Nanocrystal formation and structure rejuvenation in Al-based alloys
Authors: Matveev D , Pershina E , Volkov N , Abrosimova G
Published: November 2019

Studies of the structural evolution of the group of Al-based amorphous alloys of Al-Ni-RE (RE = La, Y, Gd) systems showed that, under the combined action of heat and deformation on the structure, one may obtain samples with different crystal sizes and different fractions of the nanocrystalline phase. Under crystallization of a heterogeneous amorphous phase, the size of the nanocrystals is smaller, and their fraction is larger than under crystallization of a homogeneous amorphous phase. The use of cryogenic cycling method allows rejuvenating the amorphous phase in partially crystalline alloys.
Post-dynamic recrystallization of the Cu-0.6Cr alloy
Authors: Aksenov D A , Asfandiyarov R N , Raab G I , Raab A G
Published: November 2019

The results of the studying the transformation of structural parameters in the samples of the Cu-0.6Cr alloy during high-temperature free upsetting and subsequent cooling at different rates with the use of different media: liquid nitrogen, water and air are presented. Using EBSD and X-ray diffraction (XRD) analysis, we demonstrate that a decrease in the cooling rate of the samples of the Cu-0.6Cr alloy after a large deformation of e~2 at a temperature of 800-850 °C promotes the formation of smaller structural fragments, an increase in the dislocation density and a reduction in the fraction of high-angle boundaries.
Structure of deformed Al-based amorphous alloys
Authors: Matveev D , Pershina E , Postnova E , Fokin D , Aronin A
Published: November 2019

The structure of deformed Al-based amorphous alloys was studied by X-ray diffraction, scanning, transmission and probe electron microscopy. It has been found that the material in the shear bands has lower values of Young’s modulus and density. The shear band width is about 50 nm. In the band, no redistribution of the alloy components typical for phase separation is observed. The size of the regions with reduced Young’s modulus around the shear band is in the range from several tenths of a micron to 1 µm.
Study of the processing of long-length billets by continuous free bending
Authors: Asfandiyarov R N , Aksenov D A , Raab G I
Published: November 2019

This paper investigates the features of deformation processing by continuous free bending in rollers, aimed at enhancing the mechanical properties of long-length metallic billets without any change in their cross section. As the material for the investigation, we selected a chromium-zirconium bronze for electrical engineering applications, used, for example, for the production of contact wires that require high mechanical characteristics. Computer simulation reveals that during the processing by continuous free bending, a gradient field of accumulated strain is formed, with maximum values in the peripheral region and with minimum values in the center of the billet. It is found that during bending, by the 6th cycle the peripheral layers of the billet accumulate a strain of e~2, and the damage reaches a value of ~1. In the process of verification by means of a physical experiment, cracks emerge on the billet surface during the 6th cycle, confirming the simulation data. Structural analysis shows that during multi-cycle processing by this method, a gradient type of structure is formed. An important advantage of the processing by continuous free bending is the enhancement of the mechanical properties of long-length samples without any reduction in the cross-sectional area: e.g., after 4 processing cycles the ultimate tensile strength increased from 250±20 to 380±20 MPa, and the variation of the cross-sectional area was ~5-7%. The obtained results are in agreement with some principles of severe plastic deformation processing.
SEM and AFM analysis of the shear bands in Zr-based BMG after HPT
Authors: Astanin V , Gunderov D , Boltynjuk E , Ubyivovk E , Churakova A , Gunderova S
Published: November 2019

The surface relief formed by shear bands in bulk metallic glasses (BMG) under high-pressure torsion (HPT) has been investigated by the method of scanning electron microscopy (SEM) and atomic force microscopy (AFM). For this purpose, two halves of disks of the bulk metallic glass were jointed together and processed by HPT. The SEM examination of the internal surfaces of two joint halves of an HPT-processed disk allowed to study the formation and accumulation of shear bands under an increased imposed strain. The maximum density of the shear bands is observed at the edges of the HPT samples and in areas adjacent to the upper anvils. The observed minimum shear band spacing is equal to 0.5 μm after HPT processing for 5 revolutions.
On strengthening of ultrafine grained austenitic steels subjected to large strain deformation
Authors: Belyakov A , Odnobokova M , Yanushkevich Z , Nazarova M , Kaibyshev R
Published: November 2019

Our current results on the structure-property relationship in ultrafine grained (UFG) austenitic steels, subjected to large strain deformation under conditions of cold to warm working are critically reviewed. Commonly, the grain size and dislocation density that evolve in UFG steels and alloys during large strain deformation depends sensitively on the processing conditions, i.e., temperature and strain rate. The grain size decreases, and the dislocation density increases with a decrease in deformation temperature. Therefore, a unique power-law relationship with a grain size exponent of -0.6 holds between the deformation grain size and the dislocation density. A power-law function between the grain size and dislocation density is obtained for UFG steels even after annealing. Thus, the yield strength of UFG steels can be expressed by a modified Hall-Petch-type relationship, which includes the dislocation strengthening, by using the grain size or dislocation density as a unique variable.
Influence of severe plastic deformation on the structure and mechanical properties of eutectic Al-Zn-Mg-Fe-Ni alloy
Authors: Brodova I G , Petrova A N , Akopyan T K
Published: November 2019

The structure and phase evolution of the new eutectic high strength aluminium alloy Nikalin were investigated under high pressure torsion (HPT) by several numbers of the revolution of the anvil. The chemical composition of the investigated Nikalin alloy was as follows: Al (base)– 7.22Zn–2.95 Mg–0.52 Fe–0.57 Ni–0.2 Zr. (wt.%). The initial material was a coarse grained cast ingot after homogenization. It was established that the HPT process resulted in the deformation dissolution of the nanosized T-phase precipitates and the formation of a supersaturated aluminum solid solution simultaneously with the strong refinement of the structure to the grain-subgrain size of 130-150 nm. Due to that, the yield stress of the HPT alloy increased by a factor of 1.5, the ultimate tensile strength increased by a factor of 1.4, while preserving good ductility of 6-7%. The observed effect of the additional supersaturated solution upon HPT relative to the homogenized state appeared upon post-deformation annealing at 140 °C. An increase in the microhardness of the HPT alloy due to the MgZn2 phase precipitation was observed at 0.5- hours of annealing.
Contribution of structural factors to the specific electrical resistance of nanostructured Cu-Cr-Zr alloy
Authors: Chembarisova R G , Sarkeeva E A , Alexandrov I V
Published: November 2019

The specific resistance of the nanostructured Cu-1.8wt.%Cr-0.8wt.%Zr alloy has been analyzed by means of analytical modeling. The contribution of different structural parameters to the specific resistance of the material has been estimated.
Microstructure and mechanical properties of the ultrafine-grained TiNi alloy after multiple martensitic transformations and subsequent aging
Authors: Churakova A A , Gunderov D V
Published: November 2019

In this paper, we investigate the effect of preliminary thermal cycling in the temperature range of martensitic transformation on the aging processes in the ultrafine-grained Ti49.0Ni51.0 alloy, using as an example the examination of the microstructure, mechanical properties and fractography. Our studies show that preliminary thermal cycling leads to a significant increase in the density of dislocations that promote the intensification of the aging process and thereby enhance the strength and functional characteristics of the TiNi alloy in the ultrafine-grained state.
Comparative analysis of the microstructure and mechanical properties of an Al-Cu-Mg-Ag alloy peak-aged at relatively low and high temperatures
Authors: Gazizov M , Holmestad R , Kaibyshev R
Published: November 2019

The mechanical properties and microstructure have been investigated in the Al-4.35Cu-0.46Mg-0.63Ag-0.36Mn-0.12Ti-0.04Fe alloy (in wt. %) peak-aged at 150 °C and 190 °C. The yield stresses (YS) and the ultimate tensile strength (UTS) were insignificantly higher by 15 MPa and 5 MPa, respectively, after peak-aging at 150 °C for 24 h compared with 190 °C for 1.5 h. Elongation-to-failure (δ) was the same (~6%) in both states. Microstructure analysis showed great differences in the morphology of precipitates within grain/subgrain interiors, as well as in the structure of regions adjacent to grain boundaries (GBs). Relationships between strength/ductile properties and microstructure were discussed.
Features of mass transfer by N-crowdions in fcc Ni3Al lattice
Authors: Bayazitov A M , Dmitriev S V , Zakharov P V , Shepelev I A , Fomin S Yu , Korznikova E A
Published: November 2019

Crowdions being interstitial atoms located in closely packed atomic rows, play an important role in relaxation processes occurring in metals and alloys under severe external impacts effectively transferring mass and energy. Dynamics of crowdions motion is well studied for pure metals, while for intermetallic alloys this issue has not previously been addressed. It was earlier shown that the so-called N crowdion that involves more than one atom in its 1D motion is much more effective in frames of propagation path and excitation energy that 1-crowdion. In the present study, the motion of 1- and 2-crowdions in the Ni3Al intermetallic alloy, was studied by means of the molecular dynamics method. N-crowdion was excited by providing the same value of initial energy to N neighbouring atoms along the close-packed atomic row. It was shown that the studied crowdions can propagate along the biatomic close-packed row, but show strong instability when moving in monatomic close-packed directions. It has been established that 2-crowdions have a mean free path 2-2.5 times longer than 1-crowdions with the same initial velocity. It was also revealed that the mean free path of the nickel atom initiated crowdion than that initiated on the aluminium atom. The results suggest a higher efficiency of 2-crowdions in mass transfer in the Ni3Al intermetallic alloy. In further works, it is proposed to study the possibility of launching 2-crowdions by bombarding the crystal surface with biatomic molecules.