Si-Young Sung
,
Bong-Jae Choi
,
Beom-Suck Han
,
Han-Jun Oh
,
Young-Jig Kim
材料科学技术（英文）
The alpha-case formation reactions between Ti and investment molds (Al2O3, ZrSiO4, ZrO2, CaO stabilized ZrO2) were evaluated in a plasma arc melting furnace. Regardless of thermodynamic approaches, there were distinct alpha-case formations. The reaction products were characterized by electron probe micro-analysis and transmission electron microscopy. The α-case generation between Ti and Al2O3 mold was not able to be explained by the conventional α-case formation mechanism, which is known to be formed by the interstitials, especially oxygen dissolved from mold materials. However, from our experimental results and thermodynamic calculations, it was confirmed that the α-case is formed not only by an interstitial element but also by substitutional metallic elements dissolved from mold materials. Our newly established α-case formation mechanism will surely lead to a variety of significant applications of the α-case controlled Ti casting.
关键词:
Titanium
,
null
,
null
,
null
Bong-Jae Choi
,
Si-Young Sung
,
Myoung-Gyun Kim
,
Young-Jig Kim
材料科学技术（英文）
The main purpose of this study is an in-situ synthesis of (TiB+TiC) hybrid titanium matrix composites (TMCs) by vacuum induction melting method and to verify its mechanical properties. The melting route was adopted to synthesize the commercial pure titanium (cp Ti) and granular boron carbide (B4C). The reinforcements, the fraction of 10 vol. pct, were formed by adding 1.88 wt pct B4C to cp Ti. After in-situ synthesis of TMCs, electron probe micro-analysis elemental mapping was carried out to confirm the distribution and shape of reinforcements. The cone-on-disk type sliding wear test was also done for the identification of TMCs. It is concluded that (TiB+TiC) hybrid TMCs can be in-situ synthesized and has better wear properties than H13.
关键词:
Titanium matrix composites
,
null
,
null
,
null
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
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
郝玉琳
,
杨锐
,
李述军
,
崔玉友
,
李东
,
M.Niimomi
金属学报
doi:10.3321/j.issn:0412-1961.2002.z1.036
研究了Ti-29Nb-13Ta-4.6Zr医用钛合金时效处理对Young's模量和力学性能的影响.实验结果表明:在采用的热处理区间,合金的Young's模量具有组织敏感性.对于具有(α+β)、(α+β+ω)和(β+ω)组织的合金,Young's模量的增加总是伴随着强度和硬度的提高以及塑性的降低.对于具有(β+ω)组织的合金,由于其强度低、模量高和塑性差而不适合作为生物材料.对于具有(α+β)组织的合金,各相体积含量是影响模量和力学性能的主要因素.
关键词:
生物材料
,
Young's模量
,
力学性能
,
内耗
,
相变
