It is reasonable to state that if there were no seismic low velocity zone(LVZ)beneath ocean basins,there would be no seafloor spreading and plate tectonics.Over the past 50 years,plate tectonics has been developed int...It is reasonable to state that if there were no seismic low velocity zone(LVZ)beneath ocean basins,there would be no seafloor spreading and plate tectonics.Over the past 50 years,plate tectonics has been developed into a powerful theory with unquestionable and irrefutable lines of evidence and predictive efficacies.Yet,markedly different views remain prevalent on the origin of the LVZ.These include the effect of incipient melt[1,2],weak asthenosphere dictated by hydrous olivine[3],solid-state rheology change in response to optimal pressure and temperature conditions in the upper mantle[4],and mantle temperature variation[5].展开更多
The non-linear effects of different initial melt temperatures on the microstructure evolution during the solidification process of liquid Mg7Zn3 alloys were investigated by molecular dynamics simulation, The microstru...The non-linear effects of different initial melt temperatures on the microstructure evolution during the solidification process of liquid Mg7Zn3 alloys were investigated by molecular dynamics simulation, The microstructure transformation mechanisms were analyzed by several methods. The system was found to be solidified into amorphous structures from different initial melt temperatures at the same cooling rate of 1×10^12 K/s, and the 1551 bond-type and the icosahedron basic cluster （12 0 12 0 ） played a key role in the microstructure transition. Different initial melt temperatures had significant effects on the final microstructures. These effects only can be clearly observed below the glass transition temperature Tg; and these effects are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. However, the changes of the average atomic energy of the systems are still linearly related with the initial melt temperatures, namely, the higher the initial melt temperature is, the more stable the amorphous structure is and the stronger the glass forming ability will be.展开更多
基金supported by the National Natural Science Foundation of China(91958215)the Ministry of Education Overseas Expertise Introduction Project for Discipline Innovation(111 Project,B18048)。
文摘It is reasonable to state that if there were no seismic low velocity zone(LVZ)beneath ocean basins,there would be no seafloor spreading and plate tectonics.Over the past 50 years,plate tectonics has been developed into a powerful theory with unquestionable and irrefutable lines of evidence and predictive efficacies.Yet,markedly different views remain prevalent on the origin of the LVZ.These include the effect of incipient melt[1,2],weak asthenosphere dictated by hydrous olivine[3],solid-state rheology change in response to optimal pressure and temperature conditions in the upper mantle[4],and mantle temperature variation[5].
基金Projects(50831003,51071065,51101022,51102090) supported by the National Natural Science Foundation of China
文摘The non-linear effects of different initial melt temperatures on the microstructure evolution during the solidification process of liquid Mg7Zn3 alloys were investigated by molecular dynamics simulation, The microstructure transformation mechanisms were analyzed by several methods. The system was found to be solidified into amorphous structures from different initial melt temperatures at the same cooling rate of 1×10^12 K/s, and the 1551 bond-type and the icosahedron basic cluster （12 0 12 0 ） played a key role in the microstructure transition. Different initial melt temperatures had significant effects on the final microstructures. These effects only can be clearly observed below the glass transition temperature Tg; and these effects are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. However, the changes of the average atomic energy of the systems are still linearly related with the initial melt temperatures, namely, the higher the initial melt temperature is, the more stable the amorphous structure is and the stronger the glass forming ability will be.
