Electron diffraction was used to study the local atomic structure of Cu49Hf42Al9 metallic glasses (MGs). The amorphous nature of the MG was fully retained after the compression test. The partial radial distribution fu...Electron diffraction was used to study the local atomic structure of Cu49Hf42Al9 metallic glasses (MGs). The amorphous nature of the MG was fully retained after the compression test. The partial radial distribution functions (PRDFs) of the MG structure obtained from the atomic model using reverse Monte Carlo and density functional theory optimization display that the peaks of the first nearest-neighbour distances for Cu-Cu, Hf-Cu and Hf-Hf atomic pairs were located at 2.56 A, 2.78 A and 3.23 A, respectively. The wide distribution of PRDF for Hf-Hf atomic pair explained the high plasticity of the material.展开更多
Zr-based Zr_50Pd_40Al_10 metallic glasses has not only crystalline phases of about 5 nm in diameter but also amorphous phases. In this work, the radial distribution functions(RDFs) of amorphous structure of Zr_50Pd_40...Zr-based Zr_50Pd_40Al_10 metallic glasses has not only crystalline phases of about 5 nm in diameter but also amorphous phases. In this work, the radial distribution functions(RDFs) of amorphous structure of Zr_50Pd_40Al_10 metallic glasses were firstly measured by electron diffraction, and then Reverse Monte Carlo(RMC) optimization accompanied by density functional theory(DFT) calculations. The amorphous structure has not only short-range order but also good medium-range order. In the RDFs of its amorphous structure, the first and the second peaks are located at 2.96 ? and 4.79 ?, respectively. Partial radical distribution functions(PRDFs) show that the contributions of the first and the second nearest-neighbor distances of various atom pairs to the G(r) peak values, and the first nearest-neighbor distances of Pd–Zr and Zr–Zr atom pairs are the sources of main G(r) peak values between 2? and 6?. The competition mechanism for generating the Pd_25Zr_55 Al_20 amorphous phase and the intermetallic crystalline phase Pd_11Zr_9 is associated with the differences of atomic radius, the proportion, and the melting point of different atoms, as well as the heat of mixing between atoms, leading to an equilibrium state of the two phases. Accordingly, a composite system with intertwined nanocrystals and amorphous phases is in turn formed, and improves the stability of the material.展开更多
基金supported by the National Science Fund for Excellent Young Scholars of China (No. 51422203)the National Natural Science Foundation of China (Nos. 51572091 and 51372001)+4 种基金the Natural Science Foundation of Guangdong Province, China (No. 2018A030313395)the China Postdoctoral Science Foundation(No. 2017M610522)the Science and Technology Program of Guangzhou, China (No. 201604046027)the Fundamental Research Funds for the Central Universities (No. 2017BQ035)the fund of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP201716)
文摘Electron diffraction was used to study the local atomic structure of Cu49Hf42Al9 metallic glasses (MGs). The amorphous nature of the MG was fully retained after the compression test. The partial radial distribution functions (PRDFs) of the MG structure obtained from the atomic model using reverse Monte Carlo and density functional theory optimization display that the peaks of the first nearest-neighbour distances for Cu-Cu, Hf-Cu and Hf-Hf atomic pairs were located at 2.56 A, 2.78 A and 3.23 A, respectively. The wide distribution of PRDF for Hf-Hf atomic pair explained the high plasticity of the material.
基金supported by National Science Fund for Excellent Young Scholars of China (No. 51422203)the National Natural Science Foundation of China (Nos. 51572091 and 51372001)+4 种基金the Natural Science Foundation of Guangdong Province, China (No. 2018A030313395)the China Postdoctoral Science Foundation (No. 2017M610522)the Science and Technology Program of Guangzhou, China (No. 201604046027)the Fundamental Research Funds for the Central Universities (No. 2017BQ035)the fund of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP201716)
文摘Zr-based Zr_50Pd_40Al_10 metallic glasses has not only crystalline phases of about 5 nm in diameter but also amorphous phases. In this work, the radial distribution functions(RDFs) of amorphous structure of Zr_50Pd_40Al_10 metallic glasses were firstly measured by electron diffraction, and then Reverse Monte Carlo(RMC) optimization accompanied by density functional theory(DFT) calculations. The amorphous structure has not only short-range order but also good medium-range order. In the RDFs of its amorphous structure, the first and the second peaks are located at 2.96 ? and 4.79 ?, respectively. Partial radical distribution functions(PRDFs) show that the contributions of the first and the second nearest-neighbor distances of various atom pairs to the G(r) peak values, and the first nearest-neighbor distances of Pd–Zr and Zr–Zr atom pairs are the sources of main G(r) peak values between 2? and 6?. The competition mechanism for generating the Pd_25Zr_55 Al_20 amorphous phase and the intermetallic crystalline phase Pd_11Zr_9 is associated with the differences of atomic radius, the proportion, and the melting point of different atoms, as well as the heat of mixing between atoms, leading to an equilibrium state of the two phases. Accordingly, a composite system with intertwined nanocrystals and amorphous phases is in turn formed, and improves the stability of the material.
