Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterize...Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy.Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites.It is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass.Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load.Strengthening and fracture mechanisms of the composite are analyzed.展开更多
The electrical resistivity of Cu/Ta multilayers deposited by radio-frequency magnetron sputtering on a polyimide substrate was investigated as a function of monolayer thickness. It is found that the resistivity of the...The electrical resistivity of Cu/Ta multilayers deposited by radio-frequency magnetron sputtering on a polyimide substrate was investigated as a function of monolayer thickness. It is found that the resistivity of the multilayer increases with decreasing monolayer thickness from 500 nm to 10 nm. Two significant effects of layer interface scattering and grain boundary scattering were identified to dominate electronic transportation behavior in the Cu/Ta multilayers at different length scales. The electrical resistivity of the multilayer with monolayer thickness ranging from nanometer to submicron scales can be well described by a newly-proposed Fuchs-Sandheimair （F-S） and Mayadas-Shatzkes （M-S） combined model.展开更多
Fatigue cracking behavior from a notch was investigated at room temperature for Ti-6.SAI-3.5Mo-1.5Zr- 0.3Si （TClI） alloys with four different microstructures obtained at different cooling rates from the β transus t...Fatigue cracking behavior from a notch was investigated at room temperature for Ti-6.SAI-3.5Mo-1.5Zr- 0.3Si （TClI） alloys with four different microstructures obtained at different cooling rates from the β transus temperature. It was found that the alloy with lamellar structures consisting of α/β lamellae or acicular α＇ martensite laths had a higher fatigue crack initiation threshold from the notch, while the bimodal structure with coarse a grain had a lower fatigue cracking resistance. The alloy with α/β lamellar structure showed a higher fatigue crack growth resistance. The length scales of the microstructures were characterized to correlate with fatigue cracking behavior. Fatigue cracking mechanism related to microstructures was discussed.展开更多
Microstructure of ZnO:Mn films with various Mn concentration was investigated with XANES and XPS. The experimental results revealed a substitution of Mn in ZnO and also excluded the existence of Mn oxides or metallic ...Microstructure of ZnO:Mn films with various Mn concentration was investigated with XANES and XPS. The experimental results revealed a substitution of Mn in ZnO and also excluded the existence of Mn oxides or metallic manganese clusters. The substitutional Mn presented a divalent state and all the ZnO:Mn films were n-type. Room temperature ferromagnetism monotonously decreases with the decrease of the electron carrier concentration. The observed ferrmagnetism should come from the carrier-mediated exchange.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50890173)
文摘Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy.Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites.It is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass.Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load.Strengthening and fracture mechanisms of the composite are analyzed.
基金supported by the National Basic Research Program of China(No.2004CB619303)partially by the National Natural Science Foundation of China(No.50571103 and 50971125)(B.Zhang)appreciates the support from the Program for Changjiang Scholars and Innovative Research Team in Northeastern University(IRT0713)
文摘The electrical resistivity of Cu/Ta multilayers deposited by radio-frequency magnetron sputtering on a polyimide substrate was investigated as a function of monolayer thickness. It is found that the resistivity of the multilayer increases with decreasing monolayer thickness from 500 nm to 10 nm. Two significant effects of layer interface scattering and grain boundary scattering were identified to dominate electronic transportation behavior in the Cu/Ta multilayers at different length scales. The electrical resistivity of the multilayer with monolayer thickness ranging from nanometer to submicron scales can be well described by a newly-proposed Fuchs-Sandheimair （F-S） and Mayadas-Shatzkes （M-S） combined model.
基金supported by the National Basic Research Program of China (No. 2007CB613803)the National Natural Science Foundation of China (No.51071158)the Fundamental Research Funds for the Central Universities (No. N100702001)
文摘Fatigue cracking behavior from a notch was investigated at room temperature for Ti-6.SAI-3.5Mo-1.5Zr- 0.3Si （TClI） alloys with four different microstructures obtained at different cooling rates from the β transus temperature. It was found that the alloy with lamellar structures consisting of α/β lamellae or acicular α＇ martensite laths had a higher fatigue crack initiation threshold from the notch, while the bimodal structure with coarse a grain had a lower fatigue cracking resistance. The alloy with α/β lamellar structure showed a higher fatigue crack growth resistance. The length scales of the microstructures were characterized to correlate with fatigue cracking behavior. Fatigue cracking mechanism related to microstructures was discussed.
文摘Microstructure of ZnO:Mn films with various Mn concentration was investigated with XANES and XPS. The experimental results revealed a substitution of Mn in ZnO and also excluded the existence of Mn oxides or metallic manganese clusters. The substitutional Mn presented a divalent state and all the ZnO:Mn films were n-type. Room temperature ferromagnetism monotonously decreases with the decrease of the electron carrier concentration. The observed ferrmagnetism should come from the carrier-mediated exchange.
