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Boulbitch A, Korzhenevskii AL. Transformation toughness induced by surface tension of the crack-tip process zone interface: A field-theoretical approach. Phys Rev E 2021; 103:023001. [PMID: 33736011 DOI: 10.1103/physreve.103.023001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/11/2021] [Indexed: 11/07/2022]
Abstract
We study a crystal with a motionless crack exhibiting the transformational process zone at its tip within the field-theoretical approach. The latter enables us to describe the transformation toughness phenomenon and relate it to the solid's location on its phase diagram. We demonstrate that the zone extends backward beyond the crack tip due to the zone boundary surface tension. This setback engenders the crack-tip shielding, thus forming the transformation toughness. We obtain a quadrature expression for the effective fracture toughness using two independent approaches-(i) with the help of the elastic Green function and, alternatively, (ii) using the weight functions-and calculate it numerically applying the results of our simulations. Based on these findings, we derive an accurate analytical approximation that describes the transformation toughness. We further express it in terms of the experimentally accessible parameters of the phase diagram: the hysteresis width, the phase transition line slope, and the transformation strain.
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Affiliation(s)
| | - Alexander L Korzhenevskii
- Institute for Problems of Mechanical Engineering, Russian Academy of Sciences, Bol'shoi Prospect V.O. 61, 199178 Saint Petersburg, Russia
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Misawa M, Fukushima S, Koura A, Shimamura K, Shimojo F, Tiwari S, Nomura KI, Kalia RK, Nakano A, Vashishta P. Application of First-Principles-Based Artificial Neural Network Potentials to Multiscale-Shock Dynamics Simulations on Solid Materials. J Phys Chem Lett 2020; 11:4536-4541. [PMID: 32443935 DOI: 10.1021/acs.jpclett.0c00637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The use of artificial neural network (ANN) potentials trained with first-principles calculations has emerged as a promising approach for molecular dynamics (MD) simulations encompassing large space and time scales while retaining first-principles accuracy. To date, however, the application of ANN-MD has been limited to near-equilibrium processes. Here we combine first-principles-trained ANN-MD with multiscale shock theory (MSST) to successfully describe far-from-equilibrium shock phenomena. Our ANN-MSST-MD approach describes shock-wave propagation in solids with first-principles accuracy but a 5000 times shorter computing time. Accordingly, ANN-MD-MSST was able to resolve fine, long-time elastic deformation at low shock speed, which was impossible with first-principles MD because of the high computational cost. This work thus lays a foundation of ANN-MD simulation to study a wide range of far-from-equilibrium processes.
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Affiliation(s)
- Masaaki Misawa
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Shogo Fukushima
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Akihide Koura
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Kohei Shimamura
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Fuyuki Shimojo
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Subodh Tiwari
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089, United States
| | - Ken-Ichi Nomura
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089, United States
| | - Rajiv K Kalia
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089, United States
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089, United States
| | - Priya Vashishta
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089, United States
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3D multiscale-imaging of processing-induced defects formed during sintering of hierarchical powder packings. Sci Rep 2019; 9:11595. [PMID: 31406176 PMCID: PMC6690982 DOI: 10.1038/s41598-019-48127-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/30/2019] [Indexed: 11/08/2022] Open
Abstract
The characterization of the processing-induced defects is an essential step for developing defect-free processing, which is important to the assurance of structural reliability of brittle ceramics. The multiscale X-ray computed tomography, consisting of micro-CT as a wide-field and low-resolution system and nano-CT as a narrow-field and high-resolution system, is suitable for observing crack-like defects with small length and with very small crack opening displacement. Here we applied this powerful imaging tool in order to reveal the complicated three-dimensional morphology of defects evolved during sintering of alumina. The hierarchical packing structure of granules was the origin of several types of strength-limiting defects, which could not be eliminated due to the differential sintering of heterogeneous microstructures. This imaging technique of internal defects provides a link between the processing and the fracture strength for the development of structural materials.
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Zhang F, Reveron H, Spies BC, Van Meerbeek B, Chevalier J. Trade-off between fracture resistance and translucency of zirconia and lithium-disilicate glass ceramics for monolithic restorations. Acta Biomater 2019; 91:24-34. [PMID: 31034947 DOI: 10.1016/j.actbio.2019.04.043] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 04/07/2019] [Accepted: 04/22/2019] [Indexed: 02/04/2023]
Abstract
High strength and translucency are generally not coincident in one restorative material and there is still a continuous development for a better balance between these two properties. Zirconia and lithium-disilicate glass-ceramics are currently the most popular alternatives for monolithic restorations. In this work, the mechanical properties and more important, the slow crack growth (SCG) resistance, which rules long-term durability, were thoroughly studied for three zirconia ceramics stabilized by 3, 4 and 5 mol% yttria in comparison to lithium-disilicate glass-ceramic. Translucency versus strength maps revealed that the more translucent zirconia compositions (i.e. with higher yttria contents) fill the gap between the standard 3 mol% yttria stabilized zirconia (3Y-TZP) and lithium-disilicate. Moreover, increasing yttria content did not always result in lower strength, as values for 3 mol% and 4 mol% yttria were the same. Independent on the yttria contents, all zirconia showed similar relative susceptibility to SCG under static and cyclic conditions and were significantly more SCG-resistant than lithium-disilicate glass ceramic. A concern with higher yttria contents (5 and 4 mol%) however could lie in the higher sensitivity to defects, resulting in a larger scatter in strength. STATEMENT OF SIGNIFICANCE: In addition to the common investigations on the generally reported strength, toughness and translucency, V-KI diagrams (crack velocity versus stress-intensity factor) from fast fracture to threshold for three newly developed zirconia were directly measured by double torsion methods under static and cyclic loading conditions. The crack-growth mechanisms were analyzed in depth. Results were compared with another popular dental ceramic, namely lithium-disilicate glass-ceramic, revealing the pros and cons of polycrystalline and glass-ceramics in terms of long-term durability. This is the first time that V-KI curves are compared for the major ceramic and glass-ceramic used for dental restorations. Strength versus translucency maps for different CAD/CAM dental restorative materials were described, showing the current indication range for zirconia ceramics.
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Yoshida K, Nishiyama N, Shinoda Y, Akatsu T, Wakai F. Evaluation of effects of crack deflection and grain bridging on toughening of nanocrystalline SiO2 stishovite. Ann Ital Chir 2017. [DOI: 10.1016/j.jeurceramsoc.2017.06.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Misawa M, Ryuo E, Yoshida K, Kalia RK, Nakano A, Nishiyama N, Shimojo F, Vashishta P, Wakai F. Picosecond amorphization of SiO 2 stishovite under tension. SCIENCE ADVANCES 2017; 3:e1602339. [PMID: 28508056 PMCID: PMC5429036 DOI: 10.1126/sciadv.1602339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 03/13/2017] [Indexed: 06/07/2023]
Abstract
It is extremely difficult to realize two conflicting properties-high hardness and toughness-in one material. Nano-polycrystalline stishovite, recently synthesized from Earth-abundant silica glass, proved to be a super-hard, ultra-tough material, which could provide sustainable supply of high-performance ceramics. Our quantum molecular dynamics simulations show that stishovite amorphizes rapidly on the order of picosecond under tension in front of a crack tip. We find a displacive amorphization mechanism that only involves short-distance collective motions of atoms, thereby facilitating the rapid transformation. The two-step amorphization pathway involves an intermediate state akin to experimentally suggested "high-density glass polymorphs" before eventually transforming to normal glass. The rapid amorphization can catch up with, screen, and self-heal a fast-moving crack. This new concept of fast amorphization toughening likely operates in other pressure-synthesized hard solids.
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Affiliation(s)
- Masaaki Misawa
- Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089–0242, USA
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Emina Ryuo
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Kimiko Yoshida
- Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
| | - Rajiv K. Kalia
- Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089–0242, USA
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089–0242, USA
| | | | - Fuyuki Shimojo
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Priya Vashishta
- Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089–0242, USA
| | - Fumihiro Wakai
- Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
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