AMI: Acta Materialia最新文献_第3页

First-Principles Study of the Effect of Al and Hf Impurities on Co 3W Antiphase Boundary Energies Al和Hf杂质对Co 3W反相边界能影响的第一性原理研究

AMI: Acta Materialia Pub Date : 2021-08-01 DOI: 10.2139/ssrn.3807770

C. Nataraj, R. Sun, C. Woodward, A. van de Walle

{"title":"First-Principles Study of the Effect of Al and Hf Impurities on Co 3W Antiphase Boundary Energies","authors":"C. Nataraj, R. Sun, C. Woodward, A. van de Walle","doi":"10.2139/ssrn.3807770","DOIUrl":"https://doi.org/10.2139/ssrn.3807770","url":null,"abstract":"Abstract The effects of Al and Hf impurities on the (111) antiphase boundary (APB) energy of metastable FCC Co 3 W are investigated via ab initio calculations. Cluster expansions are used to predict the total energies of supercells containing non-dilute concentrations of impurities using Monte Carlo simulations at relevant temperatures, giving APB energies as a function of impurity concentration and temperature for each ternary system. The cluster expansions are validated by comparing with direct energy calculations of supercells of pure L1 2 Co 3 W and the effects of each impurity are compared. Two sets of compositions are explored for each system — constant ratio (constant ratio between Co and W) and sacrificial W (constant Co). It is found that sacrificial W compositions stabilize the L1 2 structure over a wider range of compositions than constant ratio compositions (given the restriction to the FCC lattice) in both systems and should be preferred. In sacrificial W compositions, Hf increases the APB energy far more than Al, particularly at higher concentrations of the impurity, and both systems exhibit little variation with respect to temperature. It is further shown that at higher concentrations of Hf, and most noticeably for Co 3 (W 0.5 Hf 0.5 ), Hf and W tend to segregate into alternating planes, unlike the corresponding Co 3 (W 0.5 Al 0.5 ), which explains the different impacts of the two impurities on the APB energy. Finally, the ratio of (111) to (100) APB energies is studied for sacrificial W compositions to understand cross slip behavior in both ternary systems.","PeriodicalId":7755,"journal":{"name":"AMI: Acta Materialia","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83543048","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}

引用次数: 2

Segmentation of Experimental Datasets Via Convolutional Neural Networks Trained on Phase Field Simulations 基于相场模拟训练的卷积神经网络分割实验数据集

AMI: Acta Materialia Pub Date : 2021-08-01 DOI: 10.2139/ssrn.3680400

Jiwon Yeom, T. Stan, Seungbum Hong, P. Voorhees

{"title":"Segmentation of Experimental Datasets Via Convolutional Neural Networks Trained on Phase Field Simulations","authors":"Jiwon Yeom, T. Stan, Seungbum Hong, P. Voorhees","doi":"10.2139/ssrn.3680400","DOIUrl":"https://doi.org/10.2139/ssrn.3680400","url":null,"abstract":"Abstract The ability to quickly analyze large imaging datasets is vital to the widespread adoption of modern materials characterization tools, and thus the development of new materials. Image segmentation can be the most subjective and time-consuming step in the data analysis workflow. A promising approach to segmentation of large materials datasets is the use of convolutional neural networks (CNNs). However, a major challenge is to obtain the images and segmentations needed for CNN training, since this requires segmentations performed by humans. We show that it is possible to segment experimental materials science data using a SegNet-based CNN that was trained only using simple phase field simulations. A test image from an in-situ solidification experiment of an Al-Zn alloy was used to parameterize the phase field simulations. The most important microstructural features required for the best CNN to “understand” the contents of the image are ranked as: (1) having training images with diffuse particle-background interfaces, (2) modifying the images by adding noise, (3) removing particles at the image edges, and (4) adding sub-images to the particles to account for the feint bands present on some dendrites. The CNN trained on phase field images segmented the experimental test image with 99.3% accuracy, comparable to CNNs trained on experimental data. This approach of using computationally generated images to train CNNs capable of segmenting experiments will accelerate the rate of materials design and discovery.","PeriodicalId":7755,"journal":{"name":"AMI: Acta Materialia","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90803075","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}

引用次数: 14

Graphene Supported MgNi Alloy Nanocomposite as a Room Temperature Hydrogen Storage Material – Experiments and Theoretical Insights 石墨烯支持的MgNi合金纳米复合材料作为室温储氢材料-实验和理论见解

AMI: Acta Materialia Pub Date : 2021-08-01 DOI: 10.2139/ssrn.3762207

S. S. Samantaray, P. Anees, Vinayan Bhaghavathi Parambath, R. S.

引用次数: 19

Dislocation Assisted Phase Separation: A Phase Field Study 位错辅助相分离:相场研究

AMI: Acta Materialia Pub Date : 2021-07-27 DOI: 10.2139/ssrn.3910594

R. Arjun Varma, P. Pant, M. Gururajan

引用次数: 3

Polarization Doping - Ab Initio Verification of the Concept: Charge Conservation and Locality 极化掺杂——概念的从头算验证:电荷守恒和局域性

AMI: Acta Materialia Pub Date : 2021-06-02 DOI: 10.2139/ssrn.3920962

A. Ahmad, P. Strak, P. Kempisty, K. Sakowski, J. Piechota, Y. Kangawa, I. Grzegory, M. Leszczyński, Z. Zytkiewicz, G. Muzioł, E. Monroy, A. Kamińska, S. Krukowski

{"title":"Polarization Doping - Ab Initio Verification of the Concept: Charge Conservation and Locality","authors":"A. Ahmad, P. Strak, P. Kempisty, K. Sakowski, J. Piechota, Y. Kangawa, I. Grzegory, M. Leszczyński, Z. Zytkiewicz, G. Muzioł, E. Monroy, A. Kamińska, S. Krukowski","doi":"10.2139/ssrn.3920962","DOIUrl":"https://doi.org/10.2139/ssrn.3920962","url":null,"abstract":"In this work, we study the emergence of polarization doping in AlxGa1−xN layers with graded composition from a theoretical viewpoint. It is shown that bulk electric charge density emerges in the graded concentration region. The magnitude of the effect, i.e., the relation between the polarization bulk charge density and the concentration gradient is obtained. The appearance of mobile charge in the wurtzite structure grown along the polar direction was investigated using the combination of ab initio and drift-diffusion models. It was shown that the ab initio results can be recovered precisely by proper parameterization of drift-diffusion representation of the complex nitride system. It was shown that the mobile charge appears due to the increase of the distance between opposite polarization-induced charges. It was demonstrated that, for sufficiently large space distance between polarization charges, the opposite mobile charges are induced. We demonstrate that the charge conservation law applies for fixed and mobile charge separately, leading to nonlocal compensation phenomena involving (i) the bulk fixed and polarization sheet charge at the heterointerfaces and (ii) the mobile band and the defect charge. Therefore, two charge conservation laws are obeyed that induces nonlocality in the system. The magnitude of the effect allows obtaining technically viable mobile charge density for optoelectronic devices without impurity doping (donors or acceptors). Therefore, it provides an additional tool for the device designer, with the potential to attain high conductivities: high carrier concentrations can be obtained even in materials with high dopant ionization energies, and the mobility is not limited by scattering at ionized impurities.","PeriodicalId":7755,"journal":{"name":"AMI: Acta Materialia","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82089974","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}

引用次数: 1

In Situ TEM Investigations of the Microstructural Changes and Radiation Tolerance in SiC Nanowhiskers Irradiated with He Ions at High Temperatures 高温下He离子辐照SiC纳米晶须组织变化及耐辐射性能的原位透射电镜研究

AMI: Acta Materialia Pub Date : 2021-05-15 DOI: 10.2139/ssrn.3674678

E. Aradi, J. Lewis-Fell, G. Greaves, Stephen E. Donnelly, J. Hinks

{"title":"In Situ TEM Investigations of the Microstructural Changes and Radiation Tolerance in SiC Nanowhiskers Irradiated with He Ions at High Temperatures","authors":"E. Aradi, J. Lewis-Fell, G. Greaves, Stephen E. Donnelly, J. Hinks","doi":"10.2139/ssrn.3674678","DOIUrl":"https://doi.org/10.2139/ssrn.3674678","url":null,"abstract":"Abstract Using in-situ transmission electron microscopy (TEM) with ion irradiation, we investigated the microstructural changes in silicon carbide nanowhiskers (SiC NWs) which were used as a model system for nanoporous SiC. Irradiations were carried out using 6 keV He ions at temperatures between 500 and 1000°C and doses up to 20 dpa. These results are compared with the irradiation effects in SiC thin foils under the same conditions to establish differences in their response to radiation damage. The irradiation temperature played a significant role in the evolution of different microstructures; at 500°C, small defect clusters were observed in the NWs together with a segregation of carbon at the surface of the NWs mapped using energy-filtered TEM (EFTEM). At 800°C, small He bubbles (2–4 nm in diameter) were observed in the NW matrix while He platelets and bubble discs formed in the foils. At 1000°C, several changes were observed in the NWs including bubbles at twin boundaries, voids and oxygen-rich precipitates. The large surface area to volume ratio enhances defect recombination supressing the defect density in the SiC NWs compared to the foils indicating high radiation tolerance; however, elemental segregation and precipitation may limit its application in advanced nuclear reactors.","PeriodicalId":7755,"journal":{"name":"AMI: Acta Materialia","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87517266","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}

引用次数: 6

Anisotropic Defect Distribution in He+-Irradiated 4h-Sic: Effect of Stress on Defect Distribution He+辐照4h-Sic中各向异性缺陷分布:应力对缺陷分布的影响

AMI: Acta Materialia Pub Date : 2021-04-04 DOI: 10.2139/ssrn.3751554

Subing Yang, Y. Nakagawa, Minako Kondo, T. Shibayama

{"title":"Anisotropic Defect Distribution in He+-Irradiated 4h-Sic: Effect of Stress on Defect Distribution","authors":"Subing Yang, Y. Nakagawa, Minako Kondo, T. Shibayama","doi":"10.2139/ssrn.3751554","DOIUrl":"https://doi.org/10.2139/ssrn.3751554","url":null,"abstract":"Abstract Irradiation-induced anisotropic swelling in hexagonal α-SiC is known to degrade the mechanical properties of SiC; however, the associated physical mechanism and microstructural process remain insufficiently understood. In this study, an anisotropic swelling condition where the surface normal direction was allowed to freely expand with constraint in the lateral direction was introduced in 4H-SiC using selected-area He+ irradiation, and the internal defect distribution was investigated using transmission electron microscopy (TEM) and advanced scanning TEM. The defect distribution was compared to that in non-selected-area He+-irradiated 4H-SiC and electron-irradiated TEM-foil 4H-SiC. An anisotropic defect distribution was observed in the selected-area He+-ion-irradiated 4H-SiC, with interstitial defects preferentially redistributed in the surface normal direction ([0004]) and negative volume defects (such as vacancies and/or carbon antisite defects) dominantly located in the lateral directions ([ 11 2 ¯ 0 ] and [ 10 1 ¯ 0 ]). This anisotropy of the defect distribution was substantially lower in the non-selected-area He+-irradiated and electron-irradiated samples. The stress condition in the three samples was also measured and analyzed. In the selected-area He+-irradiated 4H-SiC, compressive stress was introduced in the lateral directions (([ 10 1 ¯ 0 ] and [ 11 2 ¯ 0 ])), with little stress introduced in the surface normal direction ([0004]); this stress condition was introduced at the beginning of ion irradiation. The compressive stress likely inhibits the formation of interstitial defects in the lateral directions, enhancing the anisotropy of the defect distribution in SiC.","PeriodicalId":7755,"journal":{"name":"AMI: Acta Materialia","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81715501","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}

引用次数: 18

Effect of External Electric Field on Diffusivity and Flash Sintering of 8ysz: A Molecular Dynamics Study 外电场对8ysz扩散率和闪速烧结影响的分子动力学研究

AMI: Acta Materialia Pub Date : 2021-03-01 DOI: 10.2139/ssrn.3711245

Wenwu Xu, A. Maksymenko, Shahrier Hasan, J. Meléndez, E. Olevsky

引用次数: 19

Crystallographic and Experimental Disproof of Pyramidal < c+a > Slip in Magnesium 镁中锥体< c+a >滑移的晶体学和实验反证

AMI: Acta Materialia Pub Date : 2021-03-01 DOI: 10.2139/ssrn.3793928

Yan Huang, Xinliang Yang, Jun Jiang

引用次数: 0

Spinodal Decomposition Stabilizes Plastic Flow in a Nanocrystalline Cu-Ti Alloy 纳米晶Cu-Ti合金的自旋分解稳定塑性流动

AMI: Acta Materialia Pub Date : 2021-02-19 DOI: 10.2139/ssrn.3793931

J. Rosalie, O. Renk, R. Pippan

引用次数: 1