Mg-Zn-Y alloys with long-period stacking ordered structures were prepared by an ingot casting method. The corrosion performance of Mg-Zn-Y alloys was studied by combining gas-collecting test, immersion test and electr...Mg-Zn-Y alloys with long-period stacking ordered structures were prepared by an ingot casting method. The corrosion performance of Mg-Zn-Y alloys was studied by combining gas-collecting test, immersion test and electrochemical measurements in order to determine the corrosion rate and mechanism of the alloys. The results showed that the volume fraction of Mg（12）YZn phase increased and the shape of the Mg（12）YZn phase changed from discontinuous to continuous net-like with increasing Zn and Y content. The corrosion rate of the alloys greatly depended on the distribution and volume fraction of the Mg（12）YZn phase. Corrosion products appeared at the junction of Mg phase and Mg（12）YZn phase, indicating that the Mg（12）YZn phase accelerated galvanic corrosion of Mg matrix. Mg（97）Zn1Y2 alloy shows the lowest corrosion rate due to the continuous distribution of Mg（12）YZn phase.展开更多
The recent development of high-strength magnesium alloys is focused on the role of the strengthening phases with a novel long-period stacking-ordered (LPSO) structure. This review detailed the main factors influencing...The recent development of high-strength magnesium alloys is focused on the role of the strengthening phases with a novel long-period stacking-ordered (LPSO) structure. This review detailed the main factors influencing the formation of LPSO phases, including alloying ele-ments, preparation methods, and heat treatments. Furthermore, process control in structure types, formation and transformation behavior, strengthening and toughening mechanisms of the LPSO phase were discussed. Finally, the current problems and development trends of high-strength Mg-Zn-RE alloys were also put forward.展开更多
In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectr...In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectrum given by Code for Seismic Design of Buildings (GB50011-2001). Sometimes, there may be a remarkable difference be-tween them. If the PCS is lower than the corresponding code design response spectrum (CDS), the seismic fortifi-cation criterion for the key projects would be lower than that for the general industry and civil buildings. In the paper, the relation between PCS and CDS is discussed by using the ideal simple potential seismic source. The re-sults show that in the most areas influenced mainly by the potential sources of the epicentral earthquakes and the regional earthquakes, PCS is generally lower than CDS in the long periods. We point out that the long-period re-sponse spectra of the code should be further studied and combined with the probability method of seismic zoning as much as possible. Because of the uncertainties in SSE, it should be prudent to use the long-period response spectra given by SSE for key projects when they are lower than CDS.展开更多
基金support of the National Natural Science Foundation of China (No.50571073)the Ph.D. Programs Foundation of Ministry of Education of China (No. 20111402110004)the Natural Science Foundation of Shanxi Province, China (No.2009011028-3)
文摘Mg-Zn-Y alloys with long-period stacking ordered structures were prepared by an ingot casting method. The corrosion performance of Mg-Zn-Y alloys was studied by combining gas-collecting test, immersion test and electrochemical measurements in order to determine the corrosion rate and mechanism of the alloys. The results showed that the volume fraction of Mg（12）YZn phase increased and the shape of the Mg（12）YZn phase changed from discontinuous to continuous net-like with increasing Zn and Y content. The corrosion rate of the alloys greatly depended on the distribution and volume fraction of the Mg（12）YZn phase. Corrosion products appeared at the junction of Mg phase and Mg（12）YZn phase, indicating that the Mg（12）YZn phase accelerated galvanic corrosion of Mg matrix. Mg（97）Zn1Y2 alloy shows the lowest corrosion rate due to the continuous distribution of Mg（12）YZn phase.
基金supported by the Opening Project of Jiangsu Key Laboratory of Advanced Metallic Materials (No. AMM201007)the Natural Science Foundation of Jiangsu Province of China (No. BK2010521)
文摘The recent development of high-strength magnesium alloys is focused on the role of the strengthening phases with a novel long-period stacking-ordered (LPSO) structure. This review detailed the main factors influencing the formation of LPSO phases, including alloying ele-ments, preparation methods, and heat treatments. Furthermore, process control in structure types, formation and transformation behavior, strengthening and toughening mechanisms of the LPSO phase were discussed. Finally, the current problems and development trends of high-strength Mg-Zn-RE alloys were also put forward.
基金Shanghai Science & Technology Development Foundation (022512065) and Shanghai Construction Technology Development Foundation (A0206101).
文摘In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectrum given by Code for Seismic Design of Buildings (GB50011-2001). Sometimes, there may be a remarkable difference be-tween them. If the PCS is lower than the corresponding code design response spectrum (CDS), the seismic fortifi-cation criterion for the key projects would be lower than that for the general industry and civil buildings. In the paper, the relation between PCS and CDS is discussed by using the ideal simple potential seismic source. The re-sults show that in the most areas influenced mainly by the potential sources of the epicentral earthquakes and the regional earthquakes, PCS is generally lower than CDS in the long periods. We point out that the long-period re-sponse spectra of the code should be further studied and combined with the probability method of seismic zoning as much as possible. Because of the uncertainties in SSE, it should be prudent to use the long-period response spectra given by SSE for key projects when they are lower than CDS.
