It has been widely accepted that spherical per- iodicity generally dominates liquid and amorphous structure formation, where atoms tend to gather near spherically peri- odic shells according to Friedel oscillation. He...It has been widely accepted that spherical per- iodicity generally dominates liquid and amorphous structure formation, where atoms tend to gather near spherically peri- odic shells according to Friedel oscillation. Here it is revealed that the same order is just hidden in the atomic global packing modes of the crystalline phases relevant to bulk metallic glasses. Among the multiple nearest-neighbor dusters devel- oped from all the non-equivalent atomic sites in a given phase, there always exists a principal duster, centered by which the spherical periodicity, both topologically and chemically, is the most distinct. Then the principal dusters plus specific glue atoms just constitute the cluster-plus-glue-atom structural units shared by both metallic glasses and the corresponding crystalline phases. It is further pointed out that the spherical periodicity order represents the common structural homology of crystalline and amorphous states in the medium-range through scrutinizing all binary bulk-glass-relevant phases in Cu-（Zr, Hf）, Ni-（Nb, Ta）, Al-Ca, and Pd-Si systems.展开更多
Based on the phase field theory, the phase precipitation sequence of Ni75A110Cr15 alloy and the free energy of each phase were studied. Moreover, the interatomic potentials of Llo phase, L12 phase and DO22 phase chang...Based on the phase field theory, the phase precipitation sequence of Ni75A110Cr15 alloy and the free energy of each phase were studied. Moreover, the interatomic potentials of Llo phase, L12 phase and DO22 phase changing with temperature and concen- trations were computed through utilizing the interatomic potentials equations induced by Khachaturyan＇s relational equations between the interatomic potentials and the long-range order （LRO） parameters. Results match preceding work and demonstrate that the phase precipitation sequence of Ni75AlloCr15 alloy is the disordered phase -L10 pre-precipitation phase -L12 equilibrium phase -L12＋DO22 equilibrium phase. Free energies of Llo pre-precipitation phase are higher and interatomic potentials are smaller than those of L12 equilibrium phase; therefore, it is concluded that Llo phase is unstable, and phase transformation would occur to L12 which is more stable; L12 phase precipitates earlier than DO22 phase because L12＇s interaction potentials are larger than DO22＇s.展开更多
基金supported by the Science Challenge Program (JCKY2016212A504)the National Natural Science Foundation of China(11674045)
文摘It has been widely accepted that spherical per- iodicity generally dominates liquid and amorphous structure formation, where atoms tend to gather near spherically peri- odic shells according to Friedel oscillation. Here it is revealed that the same order is just hidden in the atomic global packing modes of the crystalline phases relevant to bulk metallic glasses. Among the multiple nearest-neighbor dusters devel- oped from all the non-equivalent atomic sites in a given phase, there always exists a principal duster, centered by which the spherical periodicity, both topologically and chemically, is the most distinct. Then the principal dusters plus specific glue atoms just constitute the cluster-plus-glue-atom structural units shared by both metallic glasses and the corresponding crystalline phases. It is further pointed out that the spherical periodicity order represents the common structural homology of crystalline and amorphous states in the medium-range through scrutinizing all binary bulk-glass-relevant phases in Cu-（Zr, Hf）, Ni-（Nb, Ta）, Al-Ca, and Pd-Si systems.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10902086, 51075335 and 50875217)the Basic Re-search Fund of the Northwestern Polytechnical University (Grant No. JC201005)the Doctoral Foundation of Northwestern Polytechnical University (Grant No. CX201103)
文摘Based on the phase field theory, the phase precipitation sequence of Ni75A110Cr15 alloy and the free energy of each phase were studied. Moreover, the interatomic potentials of Llo phase, L12 phase and DO22 phase changing with temperature and concen- trations were computed through utilizing the interatomic potentials equations induced by Khachaturyan＇s relational equations between the interatomic potentials and the long-range order （LRO） parameters. Results match preceding work and demonstrate that the phase precipitation sequence of Ni75AlloCr15 alloy is the disordered phase -L10 pre-precipitation phase -L12 equilibrium phase -L12＋DO22 equilibrium phase. Free energies of Llo pre-precipitation phase are higher and interatomic potentials are smaller than those of L12 equilibrium phase; therefore, it is concluded that Llo phase is unstable, and phase transformation would occur to L12 which is more stable; L12 phase precipitates earlier than DO22 phase because L12＇s interaction potentials are larger than DO22＇s.
