【Highlight】 It is the first time to realize the control of the energy state of amorphous alloys from the perspective of composition. It is found that high mixing entropy can improve the energy state and properties of amorphous alloys. This research provides a new idea for the control of the energy state and physical properties of amorphous alloys.
Fig. 1 (a) Thermal stability of amorphous alloy; (b) Enthalpy at different temperatures; (c) Energy at different temperatures; (d) The correlation of yield strength changing with mixing entropy.
Metallic glasses (MGs) have gained widespread attention due to their superior physical properties, such as high specific strength, high fracture toughness, good soft magnetic properties, and high corrosion resistance, compared to conventional crystalline materials. It has important application prospects in aerospace, power electronics and other high-tech fields. However, it is difficult to establish a predictable structure-activity relationship on account of the disorder structure of amorphous alloys. Compared with crystalline materials, amorphous alloys are in a nonequilibrium high energy state, and their energy state can be controlled in a large range by means of relaxation and recovery. Therefore, controlling the energy state of amorphous alloys becomes a new way to improve their physical properties. The traditional method mainly regulates the energy state of amorphous alloys from the perspective of microstructure, and its limitation is that the alloy composition is fixed. Adjusting the energy state of amorphous alloys from the perspective of composition can not only get rid of this limitation, but also obtain new materials with better performance by adjusting the composition.
Recently, Juntao Huo, a professor from Ningbo Institute of Materials Technology and Engineering, CAS, and others cooperated with the Weihua Wang academician research group from Institute of Physics, CAS, Professor Maozhi Li of Renmin University of China and Professor Li-min Wang of Yanshan University to achieve the control of the energy state of amorphous alloys from the perspective of composition for the first time. The energy state of Zr-Ti-Cu-Ni-Be multi-component amorphous alloys with the change of mixing entropy was systematically studied with the method of experiment and simulation. Thermodynamic test results show that the thermal stability (Glass transition temperature Tg and Initial crystallization temperature Tx) of amorphous alloys increases with the increase of mixing entropy; Through the calculation and analysis of enthalpy, it is found that the energy state (enthalpy) increases with the increase of mixing entropy, and the results of molecular dynamics simulation further confirm this conclusion. Meanwhile, they found that the yield strength of the amorphous alloy in this system has a good linear relationship with the mixing entropy and the energy state, indicating that the energy state of the amorphous alloy can be changed by adjusting the mixing entropy, thus regulating its mechanical properties.
In a word, this research work shows that high mixing entropy can not only improve the energy state of amorphous alloys, but also improve their thermal stability and yield strength. The work also provides a new idea for regulating the energy state and physical properties of amorphous alloys.
(The original text was published on the WeChat official account of Chinese Physics Letters on March 18, 2022)