Melting kinetics of polycrystallines is analyzed on the basis of a new model which explicitly couples homogeneous and heterogeneous melting mechanisms. The distinct feature of this approach lies in its ability to evaluate not only grain-size-distribution effects on the overall melting kinetics but also competitions between the two melting mechanisms. For the first time, we reveal the three-part structure of temperature-time-transformation diagrams for melting of polycrystallines, through which it is possible to determine a critical temperature across which the dominant melting mechanism switches. The critical temperature increases as the mean-grain-diameter decreases following a negative power-law.
{"title":"Coupling of Homogeneous and Heterogeneous Melting Kinetics in Polycrystallines","authors":"M. Xiang, Yi Liao, Guomeng Li, Jun Chen","doi":"10.2139/ssrn.3399164","DOIUrl":"https://doi.org/10.2139/ssrn.3399164","url":null,"abstract":"Melting kinetics of polycrystallines is analyzed on the basis of a new model which explicitly couples homogeneous and heterogeneous melting mechanisms. The distinct feature of this approach lies in its ability to evaluate not only grain-size-distribution effects on the overall melting kinetics but also competitions between the two melting mechanisms. For the first time, we reveal the three-part structure of temperature-time-transformation diagrams for melting of polycrystallines, through which it is possible to determine a critical temperature across which the dominant melting mechanism switches. The critical temperature increases as the mean-grain-diameter decreases following a negative power-law.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89788279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The subject of this work is to carry out a source term assessment for a Hypothetical Research Reactor (HRR) and the calculation of the radiological consequences in case of Loss Of Coolant Accident (LOCA), setting out the assumptions made and the bases for these assumptions.
In the Safety Analysis Report, the maximum hypothetical accident was analyzed following these steps: -Estimation of fission product inventory in the core -Estimation fission product release to the building -Building release evaluation -Downwind doses calculation: evaluation of dose consequences from a release;
In the event of an accident in a nuclear reactor, the authorities should be in position to implement the counter-measures necessary to protect the surrounding population from radiological and the environment consequences of any releases. It is therefore necessary to monitor the progression of the accident as soon as it is detected by the plant operator in order to forecast the future behavior of the reactor so as to be able to recommend to the government authorities the implementation of counter-measures within a time compatible with the control of the risk to the population. For that purpose, it is necessary to estimate the nature, amount and kinetics of the radioactive products likely to be released out of the installation. Then, it would be possible to use PC-COSYMA codes to decide the adapted counter-measures.
{"title":"Modeling and Analysis of Radionuclide’s Transport and Source Term Evaluation Within Containment and Release to the Environment for Research Reactors","authors":"H. Graine, Kamel Zenikhri","doi":"10.2139/ssrn.3371813","DOIUrl":"https://doi.org/10.2139/ssrn.3371813","url":null,"abstract":"The subject of this work is to carry out a source term assessment for a Hypothetical Research Reactor (HRR) and the calculation of the radiological consequences in case of Loss Of Coolant Accident (LOCA), setting out the assumptions made and the bases for these assumptions. <br><br>In the Safety Analysis Report, the maximum hypothetical accident was analyzed following these steps:<br>-Estimation of fission product inventory in the core<br>-Estimation fission product release to the building<br>-Building release evaluation <br>-Downwind doses calculation: evaluation of dose consequences from a release; <br><br>In the event of an accident in a nuclear reactor, the authorities should be in position to implement the counter-measures necessary to protect the surrounding population from radiological and the environment consequences of any releases. It is therefore necessary to monitor the progression of the accident as soon as it is detected by the plant operator in order to forecast the future behavior of the reactor so as to be able to recommend to the government authorities the implementation of counter-measures within a time compatible with the control of the risk to the population. For that purpose, it is necessary to estimate the nature, amount and kinetics of the radioactive products likely to be released out of the installation. Then, it would be possible to use PC-COSYMA codes to decide the adapted counter-measures.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86399855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Kang, Soonho Kwon, Changsoo Lee, Doosun Hong, Hyuck-Mo Lee
Abstract Nitriding is the most widely employed thermochemical surface treatment to enhance the mechanical properties of steel. Specifically, gas nitriding, which is a low-temperature process for efficiently producing high-performance steels, has a disadvantage in that it consumes a large amount of time. To enhance the nitriding rate, we studied the surface alloying of iron (Fe) and its effect on ammonia (NH3) nitriding of Fe using a hierarchical protocol with density functional theory (DFT)-based microkinetics and real-time simulations. First, we considered the NH3 decomposition and nitrogen (N) diffusion mechanism on clean and alloyed (Fe-X) Fe (100) surfaces using DFT. In this study, the alloying elements including transition metals and period III to VI elements in the periodic table were considered for DFT-based computational screening. For the candidate Fe-X systems selected to improve the nitriding rate in the previous step, we calculated all the energy barriers for every elementary reaction step by varying the alloying elements and performed microkinetic analysis using those kinetic energy barriers to determine their influence on the nitriding rate. After adding consideration of thermodynamic factors, selected candidate alloys were subjected to detailed DFT calculations of the nitriding mechanism with N coverage, and based on these results, a kinetic Monte Carlo (kMC) simulation was performed to reconfirm the results under the actual nitriding process conditions. Through a hierarchical protocol, we performed a theoretical analysis and simulation of the effects of alloying elements on the nitriding rate that were not explained experimentally and suggested the best alloying element with the improved nitriding rate.
{"title":"Hierarchical Analysis of Alloying Element Effects on Gas Nitriding Rate of Fe Alloys: A DFT, Microkinetic and kMC Study","authors":"K. Kang, Soonho Kwon, Changsoo Lee, Doosun Hong, Hyuck-Mo Lee","doi":"10.2139/ssrn.3370281","DOIUrl":"https://doi.org/10.2139/ssrn.3370281","url":null,"abstract":"Abstract Nitriding is the most widely employed thermochemical surface treatment to enhance the mechanical properties of steel. Specifically, gas nitriding, which is a low-temperature process for efficiently producing high-performance steels, has a disadvantage in that it consumes a large amount of time. To enhance the nitriding rate, we studied the surface alloying of iron (Fe) and its effect on ammonia (NH3) nitriding of Fe using a hierarchical protocol with density functional theory (DFT)-based microkinetics and real-time simulations. First, we considered the NH3 decomposition and nitrogen (N) diffusion mechanism on clean and alloyed (Fe-X) Fe (100) surfaces using DFT. In this study, the alloying elements including transition metals and period III to VI elements in the periodic table were considered for DFT-based computational screening. For the candidate Fe-X systems selected to improve the nitriding rate in the previous step, we calculated all the energy barriers for every elementary reaction step by varying the alloying elements and performed microkinetic analysis using those kinetic energy barriers to determine their influence on the nitriding rate. After adding consideration of thermodynamic factors, selected candidate alloys were subjected to detailed DFT calculations of the nitriding mechanism with N coverage, and based on these results, a kinetic Monte Carlo (kMC) simulation was performed to reconfirm the results under the actual nitriding process conditions. Through a hierarchical protocol, we performed a theoretical analysis and simulation of the effects of alloying elements on the nitriding rate that were not explained experimentally and suggested the best alloying element with the improved nitriding rate.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77163128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Akash Mumbaikar, Rohan Mudgalkar, Tushar Nachan, T. Agarkar
This paper uses a TMS320F28335 processor to implement a FIR filter. Code composer studio has been used as the IDE. The DSP processor will calculate the filter coefficients based on the windowing formula and will cut off the noisy frequencies thus giving a pure wave containing only 1 fundamental frequency.
{"title":"Implementation of FIR Filters Using DSP","authors":"Akash Mumbaikar, Rohan Mudgalkar, Tushar Nachan, T. Agarkar","doi":"10.2139/ssrn.3367670","DOIUrl":"https://doi.org/10.2139/ssrn.3367670","url":null,"abstract":"This paper uses a TMS320F28335 processor to implement a FIR filter. Code composer studio has been used as the IDE. The DSP processor will calculate the filter coefficients based on the windowing formula and will cut off the noisy frequencies thus giving a pure wave containing only 1 fundamental frequency.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87323288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Ambekar, Amit A. Deshmukh, Venkata A. P. Chavali, K. Ray
A multiband configuration using semicircular patch fabricated on glass epoxy at height of 1.58mm was reported. The patch was loaded with a stub and a slot. Three bands were observed respectively at 3.5GHz with gain of 1.5dBi due to patch, 2.45 GHz with gain of 1.2dBi due to stub and 5.5GHz with gain of 1.8dBi due to slot. However detailed explanation of various resonant modes for getting multiband dual polarized response was not given in the reported work. In this paper a detailed analysis using resonance curve plots, return loss plot and vector surface current distributions explaining the multiband dual polarized response of reported work is presented. It is observed that length variations of stub and slot modify various modes of semicircular patch in such a way that results into multiband band dual polarized response. The dimension along with position of slot and stub with given feed location causes matching input impedances of TM10, TM31 and TM32 modes which results in multiband dual polarized response.
{"title":"Dual Polarized Multiband Stub and Slot Loaded Semicircular Microstrip Antenna","authors":"A. Ambekar, Amit A. Deshmukh, Venkata A. P. Chavali, K. Ray","doi":"10.2139/ssrn.3368184","DOIUrl":"https://doi.org/10.2139/ssrn.3368184","url":null,"abstract":"A multiband configuration using semicircular patch fabricated on glass epoxy at height of 1.58mm was reported. The patch was loaded with a stub and a slot. Three bands were observed respectively at 3.5GHz with gain of 1.5dBi due to patch, 2.45 GHz with gain of 1.2dBi due to stub and 5.5GHz with gain of 1.8dBi due to slot. However detailed explanation of various resonant modes for getting multiband dual polarized response was not given in the reported work. In this paper a detailed analysis using resonance curve plots, return loss plot and vector surface current distributions explaining the multiband dual polarized response of reported work is presented. It is observed that length variations of stub and slot modify various modes of semicircular patch in such a way that results into multiband band dual polarized response. The dimension along with position of slot and stub with given feed location causes matching input impedances of TM10, TM31 and TM32 modes which results in multiband dual polarized response.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90044192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study how humans make decisions when they collaborate with an artificial intelligence (AI): each instance of a classification task could be classified by themselves or by the AI. Experimental results suggest that humans and AI who work together can outperform the superior AI when it works alone. However, this only occurred when the AI delegated work to humans, not when humans delegated work to the AI. The AI profited, even from working with low-performing subjects, but humans did not delegate well. This bad delegation performance cannot be explained with algorithm aversion. On the contrary, subjects tried to follow a provided delegation strategy diligently and appeared to appreciate the AI support. However, human results suffered due to a lack of metaknowledge. They were not able to assess their own capabilities correctly, which in turn leads to poor delegation decisions. In contrast to reluctance to use AI, lacking metaknowledge is an unconscious trait. It limits fundamentally how well human decision makers can collaborate with AI and other algorithms when there is no explicit performance feedback. The results have implications for the future of work, the design of human-AI collaborative environments and education in the digital age.
{"title":"Cognitive challenges in human-AI collaboration: Investigating the path towards productive delegation","authors":"A. Fügener, Jörn Grahl, Alok Gupta, W. Ketter","doi":"10.2139/ssrn.3368813","DOIUrl":"https://doi.org/10.2139/ssrn.3368813","url":null,"abstract":"We study how humans make decisions when they collaborate with an artificial intelligence (AI): each instance of a classification task could be classified by themselves or by the AI. Experimental results suggest that humans and AI who work together can outperform the superior AI when it works alone. However, this only occurred when the AI delegated work to humans, not when humans delegated work to the AI. The AI profited, even from working with low-performing subjects, but humans did not delegate well. This bad delegation performance cannot be explained with algorithm aversion. On the contrary, subjects tried to follow a provided delegation strategy diligently and appeared to appreciate the AI support. However, human results suffered due to a lack of metaknowledge. They were not able to assess their own capabilities correctly, which in turn leads to poor delegation decisions. In contrast to reluctance to use AI, lacking metaknowledge<br>is an unconscious trait. It limits fundamentally how well human decision makers can collaborate with AI and other algorithms when there is no explicit performance feedback. The results have implications for the future of work, the design of human-AI collaborative environments and education in the digital age.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82124295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Convective heat transfer coefficients are often arbitrarily fixed in building energy simulations. This study aims to determine the convective heat transfer coefficients on the floor, the walls and the ceiling of a room with underfloor heating. To conduct this study, natural convection induced by the temperature gradient between the bottom and upper walls within square enclosure has been studied. The upper wall is brought to a sinusoidal temperature to represent its daily change. Different Rayleigh number values are considered here. The study has been carried out by solving numerically momentum and energy equations with the Boussinesq approximation. The governing equations have been solved using the Lattice Boltzmann Method. The study has been carried out for Rayleigh numbers in the range 10 ≤ Ra ≤ 106, while Prandtl number and aspect ratio are kept constant at 0.71 and 1, respectively. The numerical results in the form of average Nusselt number and gain of the time-mean Nusselt number, are presented in this study.
{"title":"Numerical Simulations Applied to Energy Efficiency for Buildings with Lattice Boltzmann Method","authors":"L. Nasseri, Z. Hireche, A. Cherif, D. Ameziani","doi":"10.2139/ssrn.3377238","DOIUrl":"https://doi.org/10.2139/ssrn.3377238","url":null,"abstract":"Convective heat transfer coefficients are often arbitrarily fixed in building energy simulations. This study aims to determine the convective heat transfer coefficients on the floor, the walls and the ceiling of a room with underfloor heating. To conduct this study, natural convection induced by the temperature gradient between the bottom and upper walls within square enclosure has been studied. The upper wall is brought to a sinusoidal temperature to represent its daily change. Different Rayleigh number values are considered here. The study has been carried out by solving numerically momentum and energy equations with the Boussinesq approximation. The governing equations have been solved using the Lattice Boltzmann Method. The study has been carried out for Rayleigh numbers in the range 10 ≤ Ra ≤ 106, while Prandtl number and aspect ratio are kept constant at 0.71 and 1, respectively. The numerical results in the form of average Nusselt number and gain of the time-mean Nusselt number, are presented in this study.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91083203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper energy analysis of thermal power plant is presented. The primary objectives of the paper are to identify and quantify the reactions having maximum energy losses. Energy analysis is based on the second law of thermodynamics which gives maximum potential work and also characterizes the irreversibility of the process. It is found that the most significant source of energy destruction as well as irreversibility in the plant. The heat losses through the boiler and condenser are considered here. The energy balance and energy destruction are performed around the different equipment of the plant. The total energy losses around the boiler are 6%while maximum energy losses occur in condenser about 66% of total energy loss. The major source of energy loss is boiler where around 77% of the fuel energy was destroyed, in the turbine it is 13% of total fuel energy was destroyed. It shows that the boiler is the major source of the irreversibility in the plant. The energy destruction losses are expressed by. Moreover, the performance of different techniques for PAH removal is also compared and discussed for a better understanding of the treatment processes.
{"title":"Exergy Analysis of a Thermal Power Plant","authors":"Gajendra Kumar Gaurav, Nitu Singh, B. Francis","doi":"10.2139/ssrn.3366867","DOIUrl":"https://doi.org/10.2139/ssrn.3366867","url":null,"abstract":"In this paper energy analysis of thermal power plant is presented. The primary objectives of the paper are to identify and quantify the reactions having maximum energy losses. Energy analysis is based on the second law of thermodynamics which gives maximum potential work and also characterizes the irreversibility of the process. It is found that the most significant source of energy destruction as well as irreversibility in the plant. The heat losses through the boiler and condenser are considered here. The energy balance and energy destruction are performed around the different equipment of the plant. The total energy losses around the boiler are 6%while maximum energy losses occur in condenser about 66% of total energy loss. The major source of energy loss is boiler where around 77% of the fuel energy was destroyed, in the turbine it is 13% of total fuel energy was destroyed. It shows that the boiler is the major source of the irreversibility in the plant. The energy destruction losses are expressed by. Moreover, the performance of different techniques for PAH removal is also compared and discussed for a better understanding of the treatment processes.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76827245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The study mainly emphasis on implementation of Aerocon blocks and panels in today’s current scenario for cost effective speedy construction. Cost Effective Speedy Construction should be possible by utilization of appropriate planning and project management, low cost materials, economical construction innovations and alternate construction techniques and strategies accessible. The selection of building materials should address the issues of nearby conditions to enhance estimation of life for the wanted ones by building innovative structures or by refining existing structures. Many studies demonstrated that a different material has been utilized in various building frameworks with conventional and current modern strategies, however just few of them have effectively been executed in Low Cost Construction projects. The present time of land has aged, and the clay bricks and mortar are replaced with alternative development materials like Aerocon blocks and Panels. Countless properties in India are built with Aerocon blocks and the strategy is quickly thriving. The primary goal of this paper is to give itemized ponder on Cost Effective Speedy Construction utilizing AEROCON blocks and panels in construction industry.
{"title":"Aerocon Blocks and Panels: Sustainable and Cost Effective Material for Speedy Construction","authors":"Akshay Wayal, M. Kumthekar","doi":"10.2139/ssrn.3366741","DOIUrl":"https://doi.org/10.2139/ssrn.3366741","url":null,"abstract":"The study mainly emphasis on implementation of Aerocon blocks and panels in today’s current scenario for cost effective speedy construction. Cost Effective Speedy Construction should be possible by utilization of appropriate planning and project management, low cost materials, economical construction innovations and alternate construction techniques and strategies accessible. The selection of building materials should address the issues of nearby conditions to enhance estimation of life for the wanted ones by building innovative structures or by refining existing structures. Many studies demonstrated that a different material has been utilized in various building frameworks with conventional and current modern strategies, however just few of them have effectively been executed in Low Cost Construction projects. The present time of land has aged, and the clay bricks and mortar are replaced with alternative development materials like Aerocon blocks and Panels. Countless properties in India are built with Aerocon blocks and the strategy is quickly thriving. The primary goal of this paper is to give itemized ponder on Cost Effective Speedy Construction utilizing AEROCON blocks and panels in construction industry.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"93 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89469480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Wang, A. Inoue, F. Kong, S. L. Zhu, E. Shalaan, F. Al-Marzouki, W. Botta, C. S. Kiminami, Y. Ivanov, A. Greer
Heating-induced crystallization of high-entropy (HE) (Fe0.25Co0.25Ni0.25Cr0.125Mo0.125)86‒89B11-14 amorphous (am) alloys is examined to develop new structural materials with low B contents. The crystallization of 11B alloy occurs in three stages: first nanoscale bcc precipitates form in the amorphous matrix, second nanoscale fcc precipitates form, and the residual amorphous phase disappears in the third stage which yields borides in addition to the bcc and fcc phases. Crystallization of 14B alloy is the same, except that the order of appearance of bcc and fcc is reversed. The bcc and fcc particle diameters are 5-15 nm and remain almost unchanged up to ~960 K. On annealing, ultrahigh hardness of 1500-1550 (unprecedented for boride-free structures) is attained just before the third crystallization stage. This hardening and the thermal stability of the novel [am + bcc + fcc] structures are remarkable at such low boron content, and encouraging for development as ultrahigh-strength alloys. The results are interpreted in terms of the nature and extent of partitioning of elemental components between the bcc/fcc phases and the amorphous matrix, and the size and defect structures of the bcc and fcc precipitates. The magnetic flux density at RT increases by precipitation of bcc and decreases by appearance of fcc. Slower quenching of the 11B alloy shows a pseudo-polymorphic crystallization that may be characteristic of multicomponent HE systems.
{"title":"Formation, Stability and Ultrahigh Strength of Novel Nanostructured Alloys by Partial Crystallization of High-Entropy (Fe 0.25Co 0.25Ni 0.25Cr 0.125Mo 0.125) 86‒89B 11‒14 Amorphous Phase","authors":"F. Wang, A. Inoue, F. Kong, S. L. Zhu, E. Shalaan, F. Al-Marzouki, W. Botta, C. S. Kiminami, Y. Ivanov, A. Greer","doi":"10.2139/ssrn.3365117","DOIUrl":"https://doi.org/10.2139/ssrn.3365117","url":null,"abstract":"Heating-induced crystallization of high-entropy (HE) (Fe<sub>0.25</sub>Co<sub>0.25</sub>Ni<sub>0.25</sub>Cr<sub>0.125</sub>Mo<sub>0.125</sub>)<sub>86‒89</sub>B<sub>11-14</sub> amorphous (am) alloys is examined to develop new structural materials with low B contents. The crystallization of 11B alloy occurs in three stages: first nanoscale bcc precipitates form in the amorphous matrix, second nanoscale fcc precipitates form, and the residual amorphous phase disappears in the third stage which yields borides in addition to the bcc and fcc phases. Crystallization of 14B alloy is the same, except that the order of appearance of bcc and fcc is reversed. The bcc and fcc particle diameters are 5-15 nm and remain almost unchanged up to ~960 K. On annealing, ultrahigh hardness of 1500-1550 (unprecedented for boride-free structures) is attained just before the third crystallization stage. This hardening and the thermal stability of the novel [am + bcc + fcc] structures are remarkable at such low boron content, and encouraging for development as ultrahigh-strength alloys. The results are interpreted in terms of the nature and extent of partitioning of elemental components between the bcc/fcc phases and the amorphous matrix, and the size and defect structures of the bcc and fcc precipitates. The magnetic flux density at RT increases by precipitation of bcc and decreases by appearance of fcc. Slower quenching of the 11B alloy shows a pseudo-polymorphic crystallization that may be characteristic of multicomponent HE systems.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83396553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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