Microstructure and creep properties of AZ61 alloy containing 1 and 3 wt.% Ca were investigated. The creep properties were examined using impression method under different stresses between 200 and 500 MPa at the temper...Microstructure and creep properties of AZ61 alloy containing 1 and 3 wt.% Ca were investigated. The creep properties were examined using impression method under different stresses between 200 and 500 MPa at the temperature ranging from 423 to 491 K. The microstructure of AZ61 alloy contains α(Mg) matrix and Mg17 Al12 intermetallic phases. It is shown that adding Ca to AZ61 alloy reduces the amount of Mg17 Al12 phase via forming(Mg,Al)2 Ca phase;furthermore, increasing the Ca content to 3 wt.% leads to the formation of(Mg,Al)2 Ca phase, as well as the elimination of the Mg17 Al12 phase. Creep properties of AZ61 alloy are improved with the Ca addition. The improvement in creep properties is attributed to the reduction in the amount of Mg17 Al12 phase and the formation of(Mg,Al)2 Ca phase with high thermal stability. According to the obtained creep data, it is concluded that the pipe diffusion-climb controlled dislocation creep is the dominant creep mechanism and Ca addition has no influence on this mechanism. The effect of pre-deformation on the creep properties of AZ61+3%Ca alloy reveals that the creep resistance of the alloy depends on the continuity of(Mg,Al)2 Ca phase. It is decreased by reducing the phase continuity.展开更多
The Bureau of High-Technology Research and Development (BHRD) BHRD is in charge of management for the research and; development activities in high-technology areas in CAS, including predicting the trends of high-techn...The Bureau of High-Technology Research and Development (BHRD) BHRD is in charge of management for the research and; development activities in high-technology areas in CAS, including predicting the trends of high-technology development in the light of the demands for technology which is strategic, forward-展开更多
The world's only captive Yangtze River dolphin, QiQi,died on July 14 at the Wuhan-based Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS). At age of about 25, well advanced in years for a fr...The world's only captive Yangtze River dolphin, QiQi,died on July 14 at the Wuhan-based Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS). At age of about 25, well advanced in years for a freshwater dolphin, his death is considered as a natural one.展开更多
文摘Microstructure and creep properties of AZ61 alloy containing 1 and 3 wt.% Ca were investigated. The creep properties were examined using impression method under different stresses between 200 and 500 MPa at the temperature ranging from 423 to 491 K. The microstructure of AZ61 alloy contains α(Mg) matrix and Mg17 Al12 intermetallic phases. It is shown that adding Ca to AZ61 alloy reduces the amount of Mg17 Al12 phase via forming(Mg,Al)2 Ca phase;furthermore, increasing the Ca content to 3 wt.% leads to the formation of(Mg,Al)2 Ca phase, as well as the elimination of the Mg17 Al12 phase. Creep properties of AZ61 alloy are improved with the Ca addition. The improvement in creep properties is attributed to the reduction in the amount of Mg17 Al12 phase and the formation of(Mg,Al)2 Ca phase with high thermal stability. According to the obtained creep data, it is concluded that the pipe diffusion-climb controlled dislocation creep is the dominant creep mechanism and Ca addition has no influence on this mechanism. The effect of pre-deformation on the creep properties of AZ61+3%Ca alloy reveals that the creep resistance of the alloy depends on the continuity of(Mg,Al)2 Ca phase. It is decreased by reducing the phase continuity.
文摘The Bureau of High-Technology Research and Development (BHRD) BHRD is in charge of management for the research and; development activities in high-technology areas in CAS, including predicting the trends of high-technology development in the light of the demands for technology which is strategic, forward-
文摘The world's only captive Yangtze River dolphin, QiQi,died on July 14 at the Wuhan-based Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences (CAS). At age of about 25, well advanced in years for a freshwater dolphin, his death is considered as a natural one.
