The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy wa...The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooledcopper chill in an adiabatic mold. The location of columnar to equiaxed transition (CET) in thesolidified alloy ingot was measured. A numerical simulation for grain structure formation based onthe Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloywas evaluated by producing similar structure with the experimental one. The frequency ofheterogeneous nucleation was expressed as a probabilistic function with an exponential form ofundercooling that deter-mines the probability of nucleation event in the simulation. The value ofthe exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloyvaried with initial Si content.展开更多
Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tect...Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tectonic activity, and tectonic evolution ofthe area of the Xiamen submarine tunnel, the strike NWW 295^(。), which is the main unfavorable geological structure that affects the safety of the tunnel construction; the macrogeological prediction concludes that weathered troughs and groundwater-rich zonesformed by its larger-scale fault fracture zones are the main unfavorable geological bodiesprovides a basis for preventing the geo-logical hazards in the tunnel construction.展开更多
文摘The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooledcopper chill in an adiabatic mold. The location of columnar to equiaxed transition (CET) in thesolidified alloy ingot was measured. A numerical simulation for grain structure formation based onthe Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloywas evaluated by producing similar structure with the experimental one. The frequency ofheterogeneous nucleation was expressed as a probabilistic function with an exponential form ofundercooling that deter-mines the probability of nucleation event in the simulation. The value ofthe exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloyvaried with initial Si content.
基金Supported by the National Natural Science Foundation of China(10702072)the Education Department of Hebei Province (Z2006428)Doctoral Foundation of Hebei Normal University of Science & Technology
文摘Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tectonic activity, and tectonic evolution ofthe area of the Xiamen submarine tunnel, the strike NWW 295^(。), which is the main unfavorable geological structure that affects the safety of the tunnel construction; the macrogeological prediction concludes that weathered troughs and groundwater-rich zonesformed by its larger-scale fault fracture zones are the main unfavorable geological bodiesprovides a basis for preventing the geo-logical hazards in the tunnel construction.
