The differential scanning calorimetric(DSC) and transmission electron microanalysis (TEM) techniques were used to study the kinetic process of precipitation in matrix of cast SiC_p/2024 composites.The results showed t...The differential scanning calorimetric(DSC) and transmission electron microanalysis (TEM) techniques were used to study the kinetic process of precipitation in matrix of cast SiC_p/2024 composites.The results showed that precipitation reactions of GP zone and intermediate phase S'(Al_2CuMg)in the composites were accelerated compared with SiC-free material,the peak temperatures of both reactions were decreased.The reaction enthalpies of both the GP zone and intermediate phase S' formation in the matrix were substantially decreased after the addition of SiC.TEM analysis found that the alloying element Mg segregated at the SiC/Al interfaces,and was depleted in the matrix near the interface.The precipitation-free zones(PFZ) and precipitation-sparse zones(PSZ) formed near the interfaces,as a results,the volume fraction of precipitates in matrix was reduced.展开更多
In this paper, one level set method is applied to finding the interface of discontinuity of the conductivity in EIT(electrical impedance tomography) problem. By choosing one suitable velocity function, a level set rec...In this paper, one level set method is applied to finding the interface of discontinuity of the conductivity in EIT(electrical impedance tomography) problem. By choosing one suitable velocity function, a level set reconstruction algorithm is proposed. The theoretical results for EIT problem and regularization are given. Finally the numerical examples demonstrate that the reconstruction algorithm is efficient and stable.展开更多
文摘The differential scanning calorimetric(DSC) and transmission electron microanalysis (TEM) techniques were used to study the kinetic process of precipitation in matrix of cast SiC_p/2024 composites.The results showed that precipitation reactions of GP zone and intermediate phase S'(Al_2CuMg)in the composites were accelerated compared with SiC-free material,the peak temperatures of both reactions were decreased.The reaction enthalpies of both the GP zone and intermediate phase S' formation in the matrix were substantially decreased after the addition of SiC.TEM analysis found that the alloying element Mg segregated at the SiC/Al interfaces,and was depleted in the matrix near the interface.The precipitation-free zones(PFZ) and precipitation-sparse zones(PSZ) formed near the interfaces,as a results,the volume fraction of precipitates in matrix was reduced.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10431030, 10771138)the Shanghai Natural Science Foundation (Grant No. 07JC14001)+1 种基金the National Basic Research Program (GrantNo. 2005CB321701)Ministry of Education of China and State Administration of Foreign Experts Affairsof China under an 111 project (Grant No. B08018)
文摘In this paper, one level set method is applied to finding the interface of discontinuity of the conductivity in EIT(electrical impedance tomography) problem. By choosing one suitable velocity function, a level set reconstruction algorithm is proposed. The theoretical results for EIT problem and regularization are given. Finally the numerical examples demonstrate that the reconstruction algorithm is efficient and stable.
