Tungsten(W)thin films were prepared by magnetron sputtering onto Si(100)substrates.Their microstructures were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM)and transmission...Tungsten(W)thin films were prepared by magnetron sputtering onto Si(100)substrates.Their microstructures were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM)and transmission electron microscopy(TEM).The hardness and modulus were evaluated by nanoindentation.It is found that a 30 nm Cr sticking layer induces structure changes of deposited W film fromβ-W toα-W structure.In addition,remarkable hardness enhancement both for the deposited and annealed W films,were compared with that of bulk coarse-grained W,although their nanoindentation modulus is very close to that of corresponding bulk W.The intrinsic reasons that lead to structure changes and super hardness are discussed.展开更多
Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem ...Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem to be solved is changed to a set of infinite algebraic equations by an orthogonM function expansion method. As examples, under free boundary conditions, the numerical results of the dynamic moment concen- tration factors in the plates with two circular holes are computed. The results indicate that the parameters such as the incident wave number, the thickness of plates, and the spacing between holes have great effects on the dynamic stress distributions. The results are accurate because the refined equation is derived without any engineering hypothese.展开更多
基金supported by the National Basic Re-search Program of China(No.2004CB619302)the National Natural Science Foundation of China(No.50871083,50771078 and 50771069)
文摘Tungsten(W)thin films were prepared by magnetron sputtering onto Si(100)substrates.Their microstructures were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM)and transmission electron microscopy(TEM).The hardness and modulus were evaluated by nanoindentation.It is found that a 30 nm Cr sticking layer induces structure changes of deposited W film fromβ-W toα-W structure.In addition,remarkable hardness enhancement both for the deposited and annealed W films,were compared with that of bulk coarse-grained W,although their nanoindentation modulus is very close to that of corresponding bulk W.The intrinsic reasons that lead to structure changes and super hardness are discussed.
基金Project supported by the National Natural Science Foundation of China(Nos.51378451 and 51378245)
文摘Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem to be solved is changed to a set of infinite algebraic equations by an orthogonM function expansion method. As examples, under free boundary conditions, the numerical results of the dynamic moment concen- tration factors in the plates with two circular holes are computed. The results indicate that the parameters such as the incident wave number, the thickness of plates, and the spacing between holes have great effects on the dynamic stress distributions. The results are accurate because the refined equation is derived without any engineering hypothese.
