Y.G. Cao
,
X.Y. Sun
金属学报(英文版)
J-integral and crack opening displacement δ(COD) were important parameters for characterization of fractures in engineering materials. The relationship between J-integral and COD has been investigated for a long time and was enerally represented as J = m σyδ, where σy is the yield strength and m is a function of specimen geometry and material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis (FRASTA) for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD and fracture surface average profile, the relationship between J-integral and COD was deduced and compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.
关键词:
FRASTA
,
null
,
null
Y.G. Cao
金属学报(英文版)
To investigate the causes that led to the formation of cracks in materials, a novel method that only considered the fracture
surfaces for determining the fracture toughness parameters of J-integral for plain strain was proposed. The principle of the
fracture-surface topography analysis (FRASTA) was used. In FRASTA, the fracture surfaces were scanned by laser microscope and the
elevation data was recorded for analysis. The relationship between J-integral and fracture surface average profile for plain strain
was deduced. It was also verified that the J-integral determined by the novel method and by the compliance method matches each
other well.
关键词:
FRASTA
,
null
,
null
Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences
This paper presents a cluster approach to the calculation of the g factors for 3d(7) ions in cubic octahedral crystals, in which the parameters related to the configuration interaction and the covalency reduction effects are obtained from optical spectra of the studied crystals, and so no adjustable parameters are applied. From the approach, the g factors for MgO:Co2+ and CaO:Co2+ are calculated. The calculated results show good agreement with the observed values. The experimental values of g < 4.333 (the first order value in absence of configuration and covalency interactions) for MgO:Co2+ and g > 4.333 for CaO:Co2+ are also explained.
关键词:
electron paramagnetic resonance (EPR);crystal-field theory;Co2+ ion;MgO;CaO
Communications in Theoretical Physics
The calculations of the whole energy spectrum and the g factor of the ground state for CaO:Ni2+ at normal pressure and their pressure-induced shifts have been carried out on the basis of the theory of pressure-induced shifts and the diagonalization of the complete dg energy matrix in a regular octahedral field. The calculated results are in very good agreement with experimental data. The physical essentials of the pressure-induced shifts of typical levels and g factor for the ground state have been revealed by using the wavefunctions and energy spectra at various pressures.
关键词:
high pressure;ligand field;energy spectra;optical properties;electronic spin resonance
Journal of Superconductivity and Novel Magnetism
The local structure and the g factors (g(x), g(y), and g(z)) of the Cu(2+) site in Y(2)BaCuO(5) are theoretically studied using the perturbation formulas of the g factors for a 3d(9) ion in orthorhombically elongated octahedra. The orthorhombic field parameters in these formulas are determined from the superposition model and the local geometry of the system. From the calculations, the oxygen octahedron is found to undergo the local elongation Delta Z (approximate to 0.05 angstrom) along c-axis and the relative bond length variation Delta X (approximate to 0.1 angstrom) along a- and b-axes, respectively. The calculated g factors based on the above local structure are in good agreement with the experimental data. The relationships between the anisotropies of the g factors and the low symmetrical (orthorhombic) distortions of the Cu(2+) site in Y(2)BaCuO(5) are discussed.
关键词:
Crystal fields and spin Hamiltonians;Electron paramagnetic resonance;Cu(2+);Y(2)BaCuO(5);crystal
Journal of Alloys and Compounds
The subsolidus phase relations of the system Y(2)O(3) -CaO-B(2)O(3) are investigated by means of X-ray diffraction (XRD) analyses. There are six binary compounds and three ternary compounds in this system. The phase diagram comprises 13 three-phase regions. The ternary compound CaYBO(4) is refined from powder XRD data by the Rietveld method. It has a warwickite-like structure with cell parameters a=10.4354(3) Angstrom, b=9.6126(2) Angstrom, c=3.5880(1) Angstrom and space group Nam. The rationality of the CaYBO(4) structure is examined by Brown bond valence model and IR spectra. (C) 2001 Elsevier Science BY. All rights reserved.
关键词:
oxide materials;crystal structure;X-ray diffraction;phase diagram;crystal-structure
于萍
,
王亚权
腐蚀学报（英文）
研究了添加0.1mass%稀土Y的铸造K38G高温合金在1000℃的恒温氧化行为.结果表明,较之不含Y的合金，含Y铸态K38G合金的氧化速率显著降低； 氧化时形成双层的外氧化膜，表层为以Cr2O3和TiO.2为主的混合氧化物层，内层为连续的Al2O3层；没有内氧化和内氮化，没有氧化膜的剥落，加入稀土Y有效地提高了氧化膜的粘附性能.
关键词:
高温氧化
,
null
,
null
,
null
于萍
,
王亚权
腐蚀学报（英文）
doi:10.3969/j.issn.1002-6495.2007.03.010
研究了添加0.1 mass%稀土Y的铸造K38G高温合金在1000℃的恒温氧化行为.结果表明,较之不含Y的合金,含Y铸态K38G合金的氧化速率显著降低;氧化时形成双层的外氧化膜,表层为以Cr2O3和TiO2为主的混合氧化物层,内层为连续的Al2O3层;没有内氧化和内氮化,没有氧化膜的剥落,加入稀土Y有效地提高了氧化膜的粘附性能.
关键词:
高温氧化
,
K38G
,
高温合金
,
稀土元素
,
Y
陈松林
,
袁林
,
冯中起
,
曾大凡
,
刘锡俊
,
曾鲁举
,
孙加林
,
王健东
材料热处理学报
镁锆砖具有优异的高温性能和抗渣性能,但生产中会出现表面龟裂等外观缺陷,为解决MgO-ZrO2耐火材料在烧结时相变导致的龟裂,研究了CaO添加剂和烧结助剂Y2O3对MgO-ZrO2材料性能的影响.结果表明,在镁锆砖中添加的CaO首先和ZrO2发生反应,而不和MgO发生反应或固溶,添加的CaO没有起到强化镁锫砖的作用,反而由于存在高温时的扩散过程和化学反应之间的定态耦合,致使CaO和Y2O3会发生逆向扩散,在晶界处富集偏析,出现非化学热力学平衡态的稳定结构,使得镁锆砖的高温韧性变差,耐热震性能变差.
关键词:
MgO-ZrO2耐火材料
,
添加剂
,
材料性能
,
非平衡态热力学
