Ultrahigh-strength and ductile superlattice alloys with nanoscale disordered interfacesScience Magazine @ScienceMagazine
A novel approach to alloy design is capable of producing superlattice materials with mechanical & thermal properties that exceed traditional limits, which could be crucial in a variety of applications, including aerospace and automotive engineering. ($)
Ultrahigh-strength and ductile superlattice alloys with nanoscale disordered interfaces
Jet turbine blades and other objects with ultrahigh strength at high temperatures are made of special alloys that are often grown as costly single crystals to help avoid failure. Yang et al. discov...
9:30 PM · Jul 29, 2020
By T. Yang 1,2; Y. L. Zhao 1,3; W. P. Li 3; C. Y. Yu 4; J. H. Luan 3; D. Y. Lin 5; L. Fan 6; Z. B. Jiao 6; W. H. Liu 7; X. J. Liu 7,8; J. J. Kai 1,3; J. C. Huang 2,3; C. T. Liu 1,2,3
1 = Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China.
2 = Hong Kong Institute for Advanced Study, City University of Hong Kong, Hong Kong, China.
3 = Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China.
4 = College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China.
5 = Software Center for High Performance Numerical Simulation and Institute of Applied Physics and Computational Mathematics, Chinese Academy of Engineering Physics, Beijing, China.
6 = Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
7 = School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, China.
8 = Institute of Materials Genome and Big Data, Harbin Institute of Technology, Shenzhen, China.
* These authors contributed equally to this work.
Science 24 Jul 2020:
Vol. 369, Issue 6502, pp. 427-432
Strength through disorder
Jet turbine blades and other objects with ultrahigh strength at high temperatures are made of special alloys that are often grown as costly single crystals to help avoid failure. Yang et al. discovered that adding a small amount of boron in a nickel-cobalt-iron-aluminum-titanium alloy creates an ultrahigh-strength material. Critically, the alloy has a nanoscale-disordered interface in between crystal grains that substantially improves the ductility while preventing high-temperature grain coarsening. This alloy design creates attractive high-temperature properties for various applications.
Science, this issue p. 427
Alloys that have high strengths at high temperatures are crucial for a variety of important industries including aerospace. Alloys with ordered superlattice structures are attractive for this purpose but generally suffer from poor ductility and rapid grain coarsening. We discovered that nanoscale disordered interfaces can effectively overcome these problems. Interfacial disordering is driven by multielement cosegregation that creates a distinctive nanolayer between adjacent micrometer-scale superlattice grains. This nanolayer acts as a sustainable ductilizing source, which prevents brittle intergranular fractures by enhancing dislocation mobilities. Our superlattice materials have ultrahigh strengths of 1.6 gigapascals with tensile ductilities of 25% at ambient temperature. Simultaneously, we achieved negligible grain coarsening with exceptional softening resistance at elevated temperatures. Designing similar nanolayers may open a pathway for further optimization of alloy properties.