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1.
The 57Fe Mössbauer effect study at 5.0 K and in an external magnetic field of 9.0 T on a high-quality stable decagonal quasicrystal Al65Co15Cu19.9Fe0.1 is presented. It is shown that the iron atoms are located in two distinct classes of sites. The values of the principal component of the electric field gradient tensor and the asymmetry parameter at these sites are, respectively, ?1.90(10)?×?1021 V/m2, 0.97(15) and ?3.95(12)?×?1021 V/m2, 0.00(17). 相似文献
2.
以Ti4040Zr4040Ni2020合金为研究对象,用铜 模吸铸法制备出直径为3mm的致密单相准晶棒,通过维氏显微硬度测定和单向压缩实验方 法研究了该合金的室温力学性能 .结果表明:Ti4040Zr4040Ni2020准晶具有良好 的弹性变形能力,室温弹性应 变可达125%.同时,它具有相对高的室温硬度(约55GPa),是普通Ti合金的15倍.T i4040
关键词:
准晶
Ti-Zr-Ni合金
解理断裂 相似文献
3.
The amounts of decreased charge at Al sites of Al-based (Al–Pd–Cr–Fe, Al–Si–Mn, and Al–Re–Si) and at Zn sites of Zn-based (Zn–Mg–Zr) quasicrystals and approximant crystals were estimated. The evaluation was done by comparisons between chemical shifts experimentally observed by soft-X-ray emission spectroscopy and the amount of valence charge obtained by Bader analysis for first principle calculations of reference materials (Al, α-Al2O3, Zn, and ZnO). Decreased charges at Al sites of Al-based quasicrystals and at Zn sites of Zn-based quasicrystals were evaluated to be 1.0–2.5 e–/atom and 1.1–1.2 e–/atom, respectively. A covalent bonding nature alloy of Al–Re–Si also showed a decrease in valence charge at Al sites. 相似文献
4.
We present the Stroh formalism for two-dimensional subsonic steady-state motion of anisotropic quasicrystals. Using this new formalism and a series of identities and properties which follow, we investigate subsonic surface and interfacial waves in anisotropic quasicrystals. Our results suggest that there exist at most three subsonic surface wave speeds. This interesting observation is quite different from the unique surface wave speed known for anisotropic crystals. The degenerate case of decagonal quasicrystalline materials is discussed in detail. 相似文献
5.
6.
S. B. Fisher 《辐射效应与固体损伤》2013,168(3-4):173-177
The various factors influencing the nucleation of radiation damage in the HVEM are reviewed. A method for obtaining quantitative information from observations is given. The effect of reirradiation at room temperature on the damage formed at elevated temperatures is shown. This effect may give experimental information concerning the strain fields surrounding large dislocation loops. 相似文献
7.
8.
A DECAGONAL QUASICRYSTAL WITH AN ARC-SHAPED CRACK 总被引:2,自引:0,他引:2
Wang Xu Zhong Zheng 《Acta Mechanica Solida Sinica》2003,16(1):8-15
A decagonal quasicrystal,which is weakened by an arc-shaped crack penetratingthrough the solid in the period direction,and which is subjected to remote uniform phonon stresses,is investigated by applying the complex variable method which is just developed by the authors.It is found that the phonon and phason stresses near the crack tips exhibit inverse square rootsingularities.The four complex stress functions characterizing the phonon and phason fields arederived.Explicit expressions for the phonon and phason stress intensity factors,crack openingdisplacements and energy release rate are also presented. 相似文献
9.
Application of rotary tillage has been increased due to less tillage passes required, reduced draft, and greater efficiency through reduction in wheel slippage. Early failure of the bearing of tractor power take-off (PTO) shaft was observed in tractors of power range 30–35 horsepower during rotary tillage. An instrumentation setup involving an extended octagonal ring transducer (EORT) was developed and installed at the bottom of the bearing to measure the axial load and the vertical component of the radial load. The horizontal component of radial load was measured by strain gauges. Based on measured loads, the bearing life was assessed. Independent variables were: operating depth, number of blades, gear setting, engine speed, and tyre size. The average axial and radial loads varied from 786–3869 N, and 134–430 N, respectively. However, bearing experienced very high peak loads during each trial. The peak axial and radial loads was recorded between 1081–7534 N and 566–1794 N, respectively. The estimated bearing life based on peak loads was 171.98–28341.39 h. Based on the findings, it may be concluded that the average loads were not sufficient to cause quick failure of PTO bearing, rather sudden peak loads might be the root cause of early failure. 相似文献
10.
利用复变函数方法,通过构造保角映射,研究了一维六方准晶中带不对称三裂纹的圆形孔口的反平面剪切问题,给出了Ⅲ型裂纹问题的应力强度因子,在极限情形下,不仅可以还原为已有的结果,而且求得一维六方准晶中L裂纹问题在裂纹尖端的应力强度因子. 相似文献