51
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Dynamic Recovery and Superelasticity of Columnar-Grained Cu–Al–Mn Shape Memory Alloy. METALS 2017. [DOI: 10.3390/met7040141] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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52
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Effect of Sintering Time on the Densification, Microstructure, Weight Loss and Tensile Properties of a Powder Metallurgical Fe-Mn-Si Alloy. METALS 2017. [DOI: 10.3390/met7030081] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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53
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54
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Shi S, Wan JF, Zuo XW, Chen NL, Zhang JH, Rong YH. A chemical-structural model for coherent martensite/parent interface in Mn-based antiferromagnetic shape memory alloys. Phys Chem Chem Phys 2016; 18:29923-29934. [PMID: 27761534 DOI: 10.1039/c6cp06415a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The martensite/parent coherent interface of Mn-based shape memory alloys (SMAs) is a significant part in the research of their martensitic transformation, reversible shape memory effect and magnetic shape memory effect. In the present work, a chemical-structural model was proposed to calculate the martensite/parent coherent interfacial energy of Mn-X (X = Cu, Fe) alloys. In this model, the coherent heterophase interfacial energy consists of chemical and structural parts. Resulting from the formation process of the heterophase interface, the chemical interfacial energy is expressed as the incremental value of bond energy, while the structural part is obtained by calculating the interfacial strain energy. The results show that the structural interfacial energy plays the chief role in the total interfacial energy, and the total interfacial energy decreases as the temperature rises when the alloy composition is fixed. In addition, the preferred orientation has noteworthy influence on the total interfacial energy. Using the proposed model, interfacial energy, interfacial entropy, interfacial enthalpy and interfacial heat capacity are found to be correlated with temperature and interface preferred orientation. Furthermore, the influences of alloy composition, modulus softening, and the index of the habit plane on the results were discussed.
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Affiliation(s)
- S Shi
- School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, 200240 Shanghai, China.
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55
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Lee H, Yoo Y, Kang T, Lee J, Kim E, Fang X, Lee S, Kim B. Stereo-epitaxial growth of single-crystal Ni nanowires and nanoplates from aligned seed crystals. NANOSCALE 2016; 8:10291-10297. [PMID: 27129106 DOI: 10.1039/c5nr08080k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Epitaxially grown anisotropic Ni nanostructures are promising building blocks for the development of miniaturized and stereo-integrated data storage kits because they can store multiple magnetic domain walls (DWs). Here, we report stereo-epitaxially grown single-crystalline Ni nanowires (NWs) and nanoplates, and their magnetic properties. Vertical and inclined Ni NWs were grown at the center and edge regions of c-cut sapphire substrates, respectively. Vertical Ni nanoplates were grown on r-cut sapphire substrates. The morphology and growth direction of Ni nanostructures can be steered by seed crystals. Cubic Ni seeds grow into vertical Ni NWs, tetrahedral Ni seeds grow into inclined Ni NWs, and triangular Ni seeds grow into vertical Ni nanoplates. The shapes of the Ni seeds are determined by the interfacial energy between the bottom plane of the seeds and the substrates. The as-synthesized Ni NWs and nanoplates have blocking temperature values greater than 300 K at 500 Oe, verifying that these Ni nanostructures can form large magnetic DWs with high magnetic anisotropy properties. We anticipate that epitaxially grown Ni NWs and nanoplates will be used in various types of 3-dimensional magnetic devices.
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Affiliation(s)
- Hyoban Lee
- Department of Chemistry, KAIST, Daejeon 34141, Korea.
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56
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Superior thermoelasticity and shape-memory nanopores in a porous supramolecular organic framework. Nat Commun 2016; 7:11564. [PMID: 27168321 PMCID: PMC4865851 DOI: 10.1038/ncomms11564] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/08/2016] [Indexed: 01/12/2023] Open
Abstract
Flexible porous materials generally switch their structures in response to guest removal or incorporation. However, the design of porous materials with empty shape-switchable pores remains a formidable challenge. Here, we demonstrate that the structural transition between an empty orthorhombic phase and an empty tetragonal phase in a flexible porous dodecatuple intercatenated supramolecular organic framework can be controlled cooperatively through guest incorporation and thermal treatment, thus inducing empty shape-memory nanopores. Moreover, the empty orthorhombic phase was observed to exhibit superior thermoelasticity, and the molecular-scale structural mobility could be transmitted to a macroscopic crystal shape change. The driving force of the shape-memory behaviour was elucidated in terms of potential energy. These two interconvertible empty phases with different pore shapes, that is, the orthorhombic phase with rectangular pores and the tetragonal phase with square pores, completely reject or weakly adsorb N2 at 77 K, respectively.
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57
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A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation. Sci Rep 2016; 6:24462. [PMID: 27080134 PMCID: PMC4832250 DOI: 10.1038/srep24462] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/29/2016] [Indexed: 11/08/2022] Open
Abstract
Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors' knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.
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58
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Yang S, Omori T, Wang C, Liu Y, Nagasako M, Ruan J, Kainuma R, Ishida K, Liu X. A jumping shape memory alloy under heat. Sci Rep 2016; 6:21754. [PMID: 26880700 PMCID: PMC4754943 DOI: 10.1038/srep21754] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 01/27/2016] [Indexed: 12/02/2022] Open
Abstract
Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L21 parent before deformation, the 2H martensite stress-induced from L21 parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.
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Affiliation(s)
- Shuiyuan Yang
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005, P.R. China
| | - Toshihiro Omori
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-02 Aoba-yama, Sendai 980-8579, Japan
| | - Cuiping Wang
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005, P.R. China
| | - Yong Liu
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798
| | - Makoto Nagasako
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Jingjing Ruan
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005, P.R. China
| | - Ryosuke Kainuma
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-02 Aoba-yama, Sendai 980-8579, Japan
| | - Kiyohito Ishida
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-02 Aoba-yama, Sendai 980-8579, Japan
| | - Xingjun Liu
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005, P.R. China.,Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University, Xiamen 361005, P. R. China
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59
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Ponniah JK, Chen H, Adetiba O, Verduzco R, Jacot JG. Mechanoactive materials in cardiac science. J Mater Chem B 2016; 4:7350-7362. [DOI: 10.1039/c6tb00069j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Mechanically active biomaterials such as shape memory materials, liquid crystal elastomers, dielectric elastomer actuators, and conductive polymers could be used in mechanical devices to augment heart function or condition cardiac cells and artificial tissues for regenerative medicine solutions.
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Affiliation(s)
| | - H. Chen
- Department of Bioengineering
- Rice University
- USA
| | - O. Adetiba
- Department of Bioengineering
- Rice University
- USA
| | - R. Verduzco
- Department of Chemical and Biomolecular Engineering
- Rice University
- USA
| | - J. G. Jacot
- Department of Bioengineering
- Rice University
- USA
- Division of Congenital Heart Surgery
- Texas Children's Hospital
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60
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Yang Y, Zhan W, Peng R, He C, Pang X, Shi D, Jiang T, Lin Z. Graphene-Enabled Superior and Tunable Photomechanical Actuation in Liquid Crystalline Elastomer Nanocomposites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:6376-81. [PMID: 26389820 DOI: 10.1002/adma.201503680] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 08/17/2015] [Indexed: 05/17/2023]
Abstract
Programmable photoactuation enabled by graphene: Graphene sheets aligned in liquid crystalline elastomers are capable of absorbing near-infrared light. They thereafter act as nanoheaters and provide thermally conductive pathways to trigger the nematic-to-isotropic transition of elastomers, leading to macroscopic mechanical deformation of nanocomposites. Large strain, high actuation force, high initial sensitivity, fast reversible response, and long cyclability are concurrently achieved in nanocomposites.
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Affiliation(s)
- Yingkui Yang
- MOE Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materialsand School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Wenjie Zhan
- MOE Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materialsand School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China
| | - Rengui Peng
- MOE Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materialsand School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China
| | - Chengen He
- MOE Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materialsand School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China
| | - Xinchang Pang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Dean Shi
- MOE Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materialsand School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China
| | - Tao Jiang
- MOE Key Laboratory for Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materialsand School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China
| | - Zhiqun Lin
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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61
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Strain glass state as the boundary of two phase transitions. Sci Rep 2015; 5:13377. [PMID: 26307500 PMCID: PMC4549630 DOI: 10.1038/srep13377] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 07/29/2015] [Indexed: 11/20/2022] Open
Abstract
A strain glass state was found to be located between B2-B19’ (cubic to monoclinic) phase transition and B2-R (cubic to rhombohedral) phase transition in Ti49Ni51 alloys after aging process. After a short time aging, strong strain glass transition was observed, because the size of the precipitates is small, which means the strain field induced by the precipitates is isotropic and point-defect-like, and the distribution of the precipitates is random. After a long time aging, the average size of the precipitates increases. The strong strain field induced by the precipitates around them forces the symmetry of the matrix materials to conform to the symmetry of the crystalline structure of the precipitates, which results in the new phase transition. The experiment shows that there exists no well-defined boundary in the evolution from the strain glass transition to the new phase transition. Due to its generality, this glass mediated phase transition divergence scheme can be applied to other proper material systems to induce a more important new phase transition path, which can be useful in the field of phase transition engineering.
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62
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Yang Y, Fu L, Marcoux C, Socolar JES, Charbonneau P, Yellen BB. Phase transformations in binary colloidal monolayers. SOFT MATTER 2015; 11:2404-2415. [PMID: 25677504 DOI: 10.1039/c5sm00009b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Phase transformations can be difficult to characterize at the microscopic level due to the inability to directly observe individual atomic motions. Model colloidal systems, by contrast, permit the direct observation of individual particle dynamics and of collective rearrangements, which allows for real-space characterization of phase transitions. Here, we study a quasi-two-dimensional, binary colloidal alloy that exhibits liquid-solid and solid-solid phase transitions, focusing on the kinetics of a diffusionless transformation between two crystal phases. Experiments are conducted on a monolayer of magnetic and nonmagnetic spheres suspended in a thin layer of ferrofluid and exposed to a tunable magnetic field. A theoretical model of hard spheres with point dipoles at their centers is used to guide the choice of experimental parameters and characterize the underlying materials physics. When the applied field is normal to the fluid layer, a checkerboard crystal forms; when the angle between the field and the normal is sufficiently large, a striped crystal assembles. As the field is slowly tilted away from the normal, we find that the transformation pathway between the two phases depends strongly on crystal orientation, field strength, and degree of confinement of the monolayer. In some cases, the pathway occurs by smooth magnetostrictive shear, while in others it involves the sudden formation of martensitic plates.
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Affiliation(s)
- Ye Yang
- Duke University, Department of Mechanical Engineering and Materials Science, Box 90300 Hudson Hall, Durham, NC 27708, USA.
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63
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Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect. Sci Rep 2015; 5:8892. [PMID: 25749549 PMCID: PMC4352871 DOI: 10.1038/srep08892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 02/10/2015] [Indexed: 11/08/2022] Open
Abstract
Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires -orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm(3) that is almost one order of larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This study provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components.
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64
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Cong D, Saha G, Barnett M. Thermomechanical properties of Ni-Ti shape memory wires containing nanoscale precipitates induced by stress-assisted ageing. Acta Biomater 2014; 10:5178-5192. [PMID: 25159371 DOI: 10.1016/j.actbio.2014.08.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/09/2014] [Accepted: 08/18/2014] [Indexed: 11/25/2022]
Abstract
This paper systematically examines the thermomechanical properties and phase transformation behaviour of slightly Ni-rich Ni-Ti biomedical shape memory wires containing homogeneously distributed nanoscale precipitates induced by stress-assisted ageing. In contrast to previous studies, particular attention is paid to the role of precipitates in impeding twin boundary movement (TBM) and its underlying mechanisms. The size and volume fraction of precipitates are altered by changing the ageing time. The martensitic transformation temperatures increase with prolonged ageing time, whereas the R-phase transformation temperature remains relatively unchanged. The stress-strain behaviour in different phase regions during both cooling and heating is comprehensively examined, and the underlying mechanisms for the temperature- and thermal-history-dependent behaviour are elucidated with the help of the established stress-temperature phase diagram. The effect of precipitates on TBM is explored by mechanical testing at 133K. It is revealed that the critical stress for TBM (σcr) increases with increasing ageing time. There is a considerable increase of 104MPa in σcr in the sample aged at 773K for 120min under 70MPa compared with the solution-treated sample, owing to the presence of precipitates. The Orowan strengthening model of twinning dislocations is insufficient to account for this increase in σcr. The back stress generation is the predominant mechanism for the interactions between precipitates and twin boundaries during TBM that give rise to the increase in σcr. Such results provide new insights into the thermomechanical properties of precipitate containing Ni-Ti biomedical shape memory wires, which are instructive for developing high-performance biomedical shape memory alloys.
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65
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Large recovery strain in Fe-Mn-Si-based shape memory steels obtained by engineering annealing twin boundaries. Nat Commun 2014; 5:4964. [PMID: 25230134 DOI: 10.1038/ncomms5964] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 08/13/2014] [Indexed: 11/09/2022] Open
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66
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Mohd Jani J, Leary M, Subic A, Gibson MA. A review of shape memory alloy research, applications and opportunities. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.matdes.2013.11.084] [Citation(s) in RCA: 2185] [Impact Index Per Article: 218.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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67
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Zhang Z, Ding X, Sun J, Suzuki T, Lookman T, Otsuka K, Ren X. Nonhysteretic superelasticity of shape memory alloys at the nanoscale. PHYSICAL REVIEW LETTERS 2013; 111:145701. [PMID: 24138254 DOI: 10.1103/physrevlett.111.145701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/16/2013] [Indexed: 06/02/2023]
Abstract
We perform molecular dynamics simulations to show that shape memory alloy nanoparticles below the critical size not only demonstrate superelasticity but also exhibit features such as absence of hysteresis, continuous nonlinear elastic distortion, and high blocking force. Atomic level investigations show that this nonhysteretic superelasticity results from a continuous transformation from the parent phase to martensite under external stress. This aspect of shape memory alloys is attributed to a surface effect; i.e., the surface locally retards the formation of martensite and then induces a critical-end-point-like behavior when the system is below the critical size. Our work potentially broadens the application of shape memory alloys to the nanoscale. It also suggests a method to achieve nonhysteretic superelasticity in conventional bulk shape memory alloys.
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Affiliation(s)
- Zhen Zhang
- Multi-Disciplinary Materials Research Center, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
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68
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Zhao YY, Li H, Hao HY, Li M, Zhang Y, Liaw PK. Microwires fabricated by glass-coated melt spinning. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:075102. [PMID: 23902101 DOI: 10.1063/1.4812331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The glass-coated melt spinning method offers a route for the manufacture of metal filaments with a few micrometers in diameter in a single operation directly from the melt. Cobalt-based amorphous wires, Cu-15.0 atomic percent (at. %) Sn shape-memory wires, and Ni2MnGa (atomic percent) ferromagnetic wires were successfully produced by this method. The cobalt-based amorphous wire is flexible, and Cu-15.0 at. % Sn shape-memory wires have the tensile elongation of 14%. However, because of chemical reaction with glass and oxidation, it is hard to make Cu-Al-Ni shape-memory wires and Ni-Nb-Sn amorphous wires. Conditions for preparing these materials were summarized, and the differences of the solidification processes among glass-coated amorphous cobalt-based wires, Cu-15.0 at. % Sn shape-memory wires, and Ni2MnGa wires were analyzed and discussed.
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Affiliation(s)
- Y Y Zhao
- State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, No. 30, Xueyuan Road, Beijing 100083, China
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69
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Miserez A, Guerette PA. Phase transition-induced elasticity of α-helical bioelastomeric fibres and networks. Chem Soc Rev 2013; 42:1973-95. [DOI: 10.1039/c2cs35294j] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Stable magnetostructural coupling with tunable magnetoresponsive effects in hexagonal ferromagnets. Nat Commun 2012; 3:873. [DOI: 10.1038/ncomms1868] [Citation(s) in RCA: 331] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 04/24/2012] [Indexed: 11/09/2022] Open
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71
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Ben-Efraim Y, Avnir D. Entrapment of organic molecules within binary metal alloys. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm34032a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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72
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Macroscopic nucleation phenomena in continuum media with long-range interactions. Sci Rep 2011; 1:162. [PMID: 22355677 PMCID: PMC3240980 DOI: 10.1038/srep00162] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 10/19/2011] [Indexed: 11/09/2022] Open
Abstract
Nucleation, commonly associated with discontinuous transformations between metastable and stable phases, is crucial in fields as diverse as atmospheric science and nanoscale electronics. Traditionally, it is considered a microscopic process (at most nano-meter), implying the formation of a microscopic nucleus of the stable phase. Here we show for the first time, that considering long-range interactions mediated by elastic distortions, nucleation can be a macroscopic process, with the size of the critical nucleus proportional to the total system size. This provides a new concept of "macroscopic barrier-crossing nucleation". We demonstrate the effect in molecular dynamics simulations of a model spin-crossover system with two molecular states of different sizes, causing elastic distortions.
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73
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74
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Omori T, Ando K, Okano M, Xu X, Tanaka Y, Ohnuma I, Kainuma R, Ishida K. Superelastic effect in polycrystalline ferrous alloys. Science 2011; 333:68-71. [PMID: 21719673 DOI: 10.1126/science.1202232] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In superelastic alloys, large deformation can revert to a memorized shape after removing the stress. However, the stress increases with increasing temperature, which limits the practical use over a wide temperature range. Polycrystalline Fe-Mn-Al-Ni shape memory alloys show a small temperature dependence of the superelastic stress because of a small transformation entropy change brought about by a magnetic contribution to the Gibbs energies. For one alloy composition, the superelastic stress varies by 0.53 megapascal/°C over a temperature range from -196 to 240°C.
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Affiliation(s)
- T Omori
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-02 Aoba-yama, Sendai 980-8579, Japan.
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75
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Abstract
This article addresses technologic advances in endodontics pertaining to new and emerging technology. Cone-beam computed tomography and optical occurrence tomography are 2 new imaging technologies that can assist the practitioner in the diagnosis of pulpal disease. The self-adjusting file and the Apexum device can be used for instrumentation and bulk debridement of an apical lesion, respectively. Neodymium:yttrium-aluminum-garnet laser, erbium:chromium:yttrium-scandium-gallium-garnet laser, EndoActivator, EndoVac, and light-activated disinfection may assist the practitioner in cleaning the root canal system. Computed tomography-guided surgery shows promise in making endodontic surgery easier, as does mineral trioxide aggregate cement for regenerative endodontic procedures.
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Affiliation(s)
- Rory E Mortman
- Endodontic Section, Atlantic Coast Dental Research Clinic, 4200 South Congress Avenue, Lake Worth, FL 33461, USA.
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76
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Dunand DC, Müllner P. Size effects on magnetic actuation in Ni-Mn-Ga shape-memory alloys. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:216-32. [PMID: 20957766 DOI: 10.1002/adma.201002753] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The off-stoichiometric Ni(2)MnGa Heusler alloy is a magnetic shape-memory alloy capable of reversible magnetic-field-induced strains (MFIS). These are generated by twin boundaries moving under the influence of an internal stress produced by a magnetic field through the magnetocrystalline anisotropy. While MFIS are very large (up to 10%) for monocrystalline Ni-Mn-Ga, they are near zero (<0.01%) in fine-grained polycrystals due to incompatibilities during twinning of neighboring grains and the resulting internal geometrical constraints. By growing the grains and/or shrinking the sample, the grain size becomes comparable to one or more characteristic sample sizes (film thickness, wire or strut diameter, ribbon width, particle diameter, etc), and the grains become surrounded by free space. This reduces the incompatibilities between neighboring grains and can favor twinning and thus increase the MFIS. This approach was validated recently with very large MFIS (0.2-8%) measured in Ni-Mn-Ga fibers and foams with bamboo grains with dimensions similar to the fiber or strut diameters and in thin plates where grain diameters are comparable to plate thickness. Here, we review processing, micro- and macrostructure, and magneto-mechanical properties of (i) Ni-Mn-Ga powders, fibers, ribbons and films with one or more small dimension, which are amenable to the growth of bamboo grains leading to large MFIS, and (ii) "constructs" from these structural elements (e.g., mats, laminates, textiles, foams and composites). Various strategies are proposed to accentuate this geometric effect which enables large MFIS in polycrystalline Ni-Mn-Ga by matching grain and sample sizes.
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Affiliation(s)
- David C Dunand
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois 60208, USA.
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Affiliation(s)
- Ji Ma
- Materials Science and Engineering Interdisciplinary Program and Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Ibrahim Karaman
- Materials Science and Engineering Interdisciplinary Program and Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA
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