Lanba Asheesh R, Hamilton Reginald F, Melanson Adrien N, Perry Emma S, Gordon Richard F
Department of Engineering Science and Mechanics, Pennsylvania State University, 212 Earth-Engineering Sciences Bldg., University Park, PA, 16802-6812, USA.
Department of Engineering, University of Southern Maine, 37 College Ave., Gorham, ME, 04038, USA.
Sci Rep. 2024 Jan 10;14(1):1046. doi: 10.1038/s41598-023-50967-8.
The actualization of high strength and ductility in alloys, in addition to providing strong, formable materials, can lead to reduced weights in practical applications. However, increasing strength typically comes at the cost of lowering the ductility and vice-versa, referred to as the strength-ductility trade-off. In this work, we investigate the thermo-mechanical response of a 3-element multifunctional NiTi-Nb nanocomposite material that overcomes this trade-off, as it exhibits a high strength of 980 MPa and an ultrahigh ductility of 58% at fracture. The remarkable properties are attributed to the underlying microstructure of Nb nanofibers dispersed in an NiTi matrix. Deformation is accommodated via the shape memory transformation of the active NiTi matrix in concert with elastoplastic deformation of Nb nanofibers embedded within the matrix. Consequently, the material exhibits multifunctionality and recovers deformation during heating via the reversion of the stress-induced martensitic transformation in the NiTi matrix. The high strength and high ductility of this 3-element nanocomposite material puts it amongst the best performing high-entropy alloys (HEAs) that are typically made up of five or more elements.
合金中高强度和高延展性的实现，除了能提供强度高且可成型的材料外，在实际应用中还能减轻重量。然而，强度的增加通常是以降低延展性为代价的，反之亦然，这被称为强度 - 延展性权衡。在这项工作中，我们研究了一种三元多功能镍钛 - 铌纳米复合材料的热机械响应，这种材料克服了这种权衡，因为它在断裂时表现出980兆帕的高强度和58%的超高延展性。这些卓越的性能归因于分散在镍钛基体中的铌纳米纤维的微观结构。变形通过活性镍钛基体的形状记忆转变与嵌入基体中的铌纳米纤维的弹塑性变形协同作用来实现。因此，该材料具有多功能性，并在加热过程中通过镍钛基体中应力诱导马氏体转变的逆转来恢复变形。这种三元纳米复合材料的高强度和高延展性使其跻身于通常由五种或更多元素组成的性能最佳的高熵合金之列。
