Hyung Hoon Kim Jun Ho Kim Jin Young Moon Ho Seong Lee Jeong Joo Kim Young Suck Chai
材料科学技术（英文）
The oxidation characteristics for Zircaloy-4 and Zirlo in the temperature range of 700−1200°C under steam supply condition were investigated by using a modified thermo-gravimetric analyzer. The specimens were oxidized for 3600 s at each temperature and then quenched in a furnace. The oxidation rate constants were measured from the weight gains to evaluate the oxidation behavior in Zircaloy-4 and Zirlo. The weight gain rates of Zirlo were lower than those of Zircaloy-4, leading to the low rate constants. The different oxidation behaviors between both cladding materials were considered to be due to the difference in their chemical compositions.
关键词:
Zircaloy-4
,
Zirlo
,
Oxidation
Zeitschrift Fur Metallkunde
Young's equation is discussed on a thermodynamic basis. The result shows that the equation is a thermodynamic equilibrium of the wetting system rather than a force balance. The equilibrium satisfies the general equilibrium condition, that is, Gibbs free energy should be minimum when the wetting equilibrium is reached. The validity of Young's equation is only limited to some special cases, namely if the droplet shape is an exact sphere sector. It implies that Young's equation can only be used in the case without the action of gravity. If the curve of the liquid surface changes, the term of cos theta in Young's equation should be replaced by another functional form of the contact angle theta. In the discussion, the author suggests that, in the case of a solid, the surface energy should be considered rather than the surface tension, and the concept of a solid surface tension should be reconsidered based on the difference between a liquid surface and a solid surface.
关键词:
Zhimin ZHOU
,
Yong ZHOU
,
Mingjun WANG
,
Chunsheng YANG
,
Ji'an CHEN
,
Wen DING
,
Xiaoyu GAO
,
Taihua ZHANG
材料科学技术（英文）
Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.
关键词:
Mechanical properties
,
金属薄膜
,
纳米压痕
Wuzhu YAN
金属学报(英文版)
doi:10.1016/S1006-7191(08)60125-8
The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method (FEM) aimed to reveal the effect of punch size on the indentation behavior of the film/substrate system. Based on the FEM results analysis, two methods was proposed to separate film's reduced Young's modulus from a film/substrate system. The first method was based on a new weight function that quantifies film's and substrate's contributions to the overall mechanical properties of the film/substrate system in the flat cylindrical indentation test. The second method, a numerical approach, including fitting and extrapolation procedures was put forward. Both of the results from the two methods showed a reasonable agreement with the one input FE model. At last, the effect of maximum indentation depth and the surface micro-roughness of the thin film on the reduced Young's modulus of the film/substrate system were discussed. The methods proposed in the present study provide some new conceptions on evaluating other properties of thin films, e.g. creep, for which a flat-ended punch is also employed.
关键词:
Indentation test
,
表观杨氏模量
,
压痕测试；压头尺寸效应；权重方程
Y. Zhou
,
C.S. Yang
,
J.A. Chen
,
G.F. Ding
,
L. Wang
,
M.J. Wang
,
Y.M. Zhang
,
T.H. Zhang
金属学报(英文版)
Microbridge testing is used to measure the Young's modulus and residual stresses of
metallic films. Nickel film microbridges with widths of several hundred microns are
fabricated by Microelectromechanical Systems. In order to measure the mechanical
properties of nickel film microbridges, special shaft structure is designed to solve the
problem of getting the load-deflection curves of metal film microbridge by Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of the microbridge load-deflection curve is proposed to evaluate the Young's modulus and residual
stress of the films simultaneously. The calculated results based on the experimental
measurements show that the average Young's modulus and residual stress are around
190GPa and 175MPa respectively, while the Young's modulus measured by Nano-
hardness method on nickel film with silicon substrate is 186.8±7.34GPa.
关键词:
nickel film microbridge
,
null
,
null
,
null
郭振丹
,
王秀芳
,
杨晓萍
,
蒋冬梅
,
马学鸣
,
宋洪伟
金属学报
doi:10.3321/j.issn:0412-1961.2008.08.002
采用纳米压入(nanoindentation)和电子背散射衍射(EBSD)技术对多晶Cu样品多个晶粒进行了微观力学性能表征和晶体取向分析.结果表明,Young's模量随晶粒表面法向方向(hkl)与(111)和(001)最小夹角的变化有明显的规律:(hkl)越接近(111),其Young's模量越大;(hkl)越接近(001),其Young's模量越小;而Young's模量随(hkl)与(110)最小夹角的变化无明显规律.硬度随(hkl)与(111),(110)和(001)最小夹角的变化均无明显规律.通过理论计算讨论了上述规律性.
关键词:
多晶铜
,
晶体取向
,
纳米压入
,
电子背散射衍射
,
Young's模量
,
硬度
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
Quaternary Ti-(20-26)Nb-(2-8)Zr-(3.5-11.5)Sn (.wt%) alloys were investigated to evaluate the effects of Zr and Sri on Young's modulus and superelasticity of Ti-Nb-based alloys. X-ray diffraction analysis showed that solution-treated alloys have beta + alpha", beta + omega, alpha" + omega, alpha", or beta microstructures. Zr and Sn increase the lattice parameters of the beta phase; for orthorhombic alpha" matensite, they increase the lattice parameter a but decrease both b and c. The martensitic start temperature of the alpha" is depressed by Zr and Sri additions, whereas the formation of athermal w is dependent on Zr and Sn contents. Differential scanning calorimetry (DSC) measurements show that 1 wt% of Nb, Zr or Sn addition decreases the martensitic start temperature by 17.6, 41.2 or 40.9 K, respectively, due to their negative effect on lattice parameter ratios of the martensite (c/a and b/a). Tensile tests were used to evaluate Young's modulus and superelasticity of the solution-treated alloys. Of the studied alloys Ti-24Nb-4Zr-7.5Sn with single P microstructure has the lowest Young's modulus of 52 GPa and recoverable elastic strain of about 2% at room temperature after cyclic strain. (c) 2006 Elsevier B.V. All rights reserved.
关键词:
Young's modulus;superelasticity;biomedical titanium alloy;martensitic;transformation;alloying effect;shape-memory behavior;mechanical-properties;biomedical applications;plastic-deformation;induced martensite;titanium-alloy;mo alloys;ti-29nb-13ta-4.6zr;ta;ti-10v-2fe-3al
Journal of Alloys and Compounds
The phase diagram of the Ho-Ni binary system was investigated by X-ray diffraction, differential thermal analysis, optical microscopy and electron probe microanalysis techniques. The existence of eight intermediate phases has been confirmed: Ho3Ni, Ho3Ni2, HoNi, HoNi2, HoNi3, HO2Ni7, HoNi5, and Ho2Ni17. The homogeneity region of the HoNi2 phase extends from 65.6 to 66.7 at.% Ni. The other phases are line compounds. No appreciable solid solubility of holmium in nickel or of nickel in holmium was observed. Ho3Ni2 exists in two structural modifications depending on the temperature. HoNi and HoNi5 melt congruently at 1060 and 1370-degrees-C respectively. There are seven peritectic reactions and three eutectic reactions in this system.
关键词:
intermetallic compounds
Applied Physics Letters
Based on a self-similar array model, we systematically investigated the axial Young's modulus (Y-axis) of single-walled carbon nanotube (SWNT) arrays with diameters from nanometer to meter scales by an analytical approach. The results show that the Y-axis of SWNT arrays decreases dramatically with the increases of their hierarchy number (s) and is not sensitive to the specific size and constitution when s is the same, and the specific Young's modulus Y-axis(s) is independent of the packing configuration of SWNTs. Our calculations also show that the Y-axis of SWNT arrays with diameters of several micrometers is close to that of commercial high performance carbon fibers (CFs), but the Y-axis(s) of SWNT arrays is much better than that of high performance CFs. (C) 2005 American Institute of Physics.
关键词:
mechanical-properties;ropes;fibers;bundles
王燕
,
常勇
,
殷绍唐
,
王晓光
,
曹余惠
人工晶体学报
doi:10.3969/j.issn.1000-985X.2002.04.014
本文采用Boltzmann分布近似,计算了不同温度下Tm→Ho的净能量转移;计算了实验中不同温度下Ho3+离子的荧光发射强度在整个Tm-Ho体系荧光发射中的比例.我们的实验和计算表明,对Tm-Ho准三能级体系采用Boltzmann分布近似,其计算结果是可信的.
关键词:
Cr,Tm,Ho∶YAG晶体
,
Boltzmann分布近似
,
能量转移效率
