With the continuous improvement of the human ability to develop material for the application of the alloy also experienced a complex process of development from the simple to the. In recent years, began the rapid development of high-entropy alloys compared to conventional alloys, breaking the alloy design ideas for a long time with one or two elements of the main elements, functionality and performance continued to improve. But at this stage, high-entropy alloys in applications from commercial application of some distance, which is mainly reflected in the high-entropy alloy strength on the balance and degree of elongation, and this is one of the main direction of many researchers. City University of Hong Kong (CityU Hong Kong) team successfully developed earlier called Al7Ti7 ((FeCoNi) 86 Al 7 Ti 7 ) of the new high-entropy alloys , this high-entropy alloy adding new elements, strength of 1.5 GPa at room temperature ( gigapascal), ductility up to 50%!
Through strengthening the nanoparticles, this new alloy strength high entropy and a conventional iron, cobalt, nickel (the FeCoNi) alloy as compared to 5 times a full solid. It is not only strong, but both ductility and toughness, break the strength and ductility incompatible with this thorny problem, remove obstacles for the future development of innovative structural materials.
(New high-entropy alloys made Al7Ti7 innovative ways to solve the strength and ductility incompatible with this thorny problem)
"The most common alloys produced by a one to two kinds of major elements, such as nickel and iron. However, we have found that by adding aluminum and titanium in the iron-cobalt-nickel alloy, the formation of large precipitated particles, the strength of the new alloy of high entropy and ductility have significantly increased, to solve the key problem of structural materials in both hard to have both. "responsible for leading the study Hongkong City Department of materials Science and Engineering, Professor Liu explained.
High strength alloys generally unstable in the plastic deformation process conditions, i.e. constriction (necking) the problem, that is, when the alloy by the high tensile strength, deformation becomes unstable, it is prone to breakage necking (local deformation), only a limited uniform elongation. Under the leadership of Professor Liu Jinchuan, the team found that adding "among multi-component metal nanoparticles," that composite nanoparticles are composed of atoms of different elements, you can not improve the stability of deformation, the new generation of new high-entropy alloy strength greatly enhanced , the deformation resistance of the alloy more uniform.
Further team identified over the formulation of the composite nanoparticles of nickel, cobalt, iron, titanium and aluminum atoms. Professor Liu explained, each nanoparticle is only 30 to 50 nanometers size, and partially replace the nickel and cobalt with iron atoms, can help reduce the "electronic value" density (valence electron), the enhanced ductility of the new alloys; on the other hand, with substituted titanium aluminum part, can greatly reduce the moisture in the air to opportunistic new alloy embrittlement occurs.
(Al7Ti7 alloy having excellent strength at room temperature, - prolonged composition)
This cutting-edge research has been published in leading academic journal "Science" (Science), entitled " among multi-component metal nanoparticles and composite alloys superior mechanical properties " ( Multicomponent nanoparticles and intermetallic Superb Mechanical Behaviors of Complex Alloys ).
"This study for the manufacture of super alloys pioneering an innovative design strategies to strengthen through the use of complex multi-component alloy nano-particles, so that the new alloy issued to the superior mechanical properties at room and elevated temperatures." Professor Liu said.
他相信，这种创新策略制造的新型高熵合金强度和延伸度表现优秀，能够在摄氏零下200度低温至1,000度高温的温度范围内都展示出良好性能，这些新合金将为进一步研发低温设备、飞机和航空高温系统以及其他领域的结构用途奠定稳健的基础，实现强度和延伸度的完美平衡。