Taking experimental path on disordering AuCuI（AAuCu8A4）composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I（AAu Cu8 A4）to keep structure ...Taking experimental path on disordering AuCuI（AAuCu8A4）composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I（AAu Cu8 A4）to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI（AAuACu84）to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called ＂retro-effect＂ about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.展开更多
The Fe-Ti binary system was re-assessed using the CALPHAD method in order to improve the capability of being extrapolated to a ternary or higher-order system. Compared with previous assessments, the main focus was put...The Fe-Ti binary system was re-assessed using the CALPHAD method in order to improve the capability of being extrapolated to a ternary or higher-order system. Compared with previous assessments, the main focus was put on the thermodynamic description of the two intermetallic compounds Fe2Ti and FeTi. The C14_Laves phase Fe2Ti was described by the two-sublattice model, which is widely used at present. By checking the homogeneity range on the boundary of the ternary systems involving the binary, the phase boundary of this compound was further confirmed. The FeTi phase with a BCC_B2 crystal structure was treated as the ordered phase of the BCC_A2 phase and a unified Gibbs energy function was used to describe both the ordered and disordered phases. Reproduction of the specific heat capacities of these compounds was another aspect paid particular attention to. Comprehensive comparisons of the calculated and experimental results regarding the phase diagram and thermodynamic properties show a good agreement between them and prove the validity of the present thermodynamic description.展开更多
Kinetics of order-disorder transition at antiphase domain boundary （APDB） formed between L12 （Ni3A1） phases is investigated using microscopic phase-field model. The results demonstrate that whether order-disorder ...Kinetics of order-disorder transition at antiphase domain boundary （APDB） formed between L12 （Ni3A1） phases is investigated using microscopic phase-field model. The results demonstrate that whether order-disorder transition happens or not depends on the atomic structure of the APDB. Accompanied with the enrichment of V and depletion of Ni and A1, the ordered APDB with phase-shift vector of a/2[100] transforms into a thin disordered phase layer. Whereas at the APDB with phase shift vector of a/2[110], which remains ordered with temporal evolution, Ni and A1 enrich and V depletes. Composition evolution of APDB with order-disorder transition favors the nucleation of DO22 phase, and the formation of disordered phase layer accelerates the growth of DO22 phase. The disordered phase caused by order-disordered transition of the APDB can be considered as the transient phase along the precipitation path of DO22 phase.展开更多
基金Project(51071181)supported by the National Natural Science Foundation of ChinaProject(2013FJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Taking experimental path on disordering AuCuI（AAuCu8A4）composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I（AAu Cu8 A4）to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI（AAuACu84）to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called ＂retro-effect＂ about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.
基金Project (IP08-092009) supported by Sino Swiss Science and Technology Cooperation (SSSTC)Project (50971136) supported by the National Natural Science Foundation of ChinaProject (1343-71134001013) supported by the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education of China
文摘The Fe-Ti binary system was re-assessed using the CALPHAD method in order to improve the capability of being extrapolated to a ternary or higher-order system. Compared with previous assessments, the main focus was put on the thermodynamic description of the two intermetallic compounds Fe2Ti and FeTi. The C14_Laves phase Fe2Ti was described by the two-sublattice model, which is widely used at present. By checking the homogeneity range on the boundary of the ternary systems involving the binary, the phase boundary of this compound was further confirmed. The FeTi phase with a BCC_B2 crystal structure was treated as the ordered phase of the BCC_A2 phase and a unified Gibbs energy function was used to describe both the ordered and disordered phases. Reproduction of the specific heat capacities of these compounds was another aspect paid particular attention to. Comprehensive comparisons of the calculated and experimental results regarding the phase diagram and thermodynamic properties show a good agreement between them and prove the validity of the present thermodynamic description.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50941020, 10902086, 50875217,and 20903075)the Natural Science Foundation of Shaanxi Province (Grant Nos.SJ08-ZT05 and SJ08-B14)the Doctorate Foundation of Northwest Polytechnical University (Grant No.CX200905)
文摘Kinetics of order-disorder transition at antiphase domain boundary （APDB） formed between L12 （Ni3A1） phases is investigated using microscopic phase-field model. The results demonstrate that whether order-disorder transition happens or not depends on the atomic structure of the APDB. Accompanied with the enrichment of V and depletion of Ni and A1, the ordered APDB with phase-shift vector of a/2[100] transforms into a thin disordered phase layer. Whereas at the APDB with phase shift vector of a/2[110], which remains ordered with temporal evolution, Ni and A1 enrich and V depletes. Composition evolution of APDB with order-disorder transition favors the nucleation of DO22 phase, and the formation of disordered phase layer accelerates the growth of DO22 phase. The disordered phase caused by order-disordered transition of the APDB can be considered as the transient phase along the precipitation path of DO22 phase.
