Jie DENG
,
Qiyi LONG
,
Chiwei LUNG
材料科学技术（英文）
In this letter, a new method was proposed to visualize the crack front in stress corrosion fracture of high strength steel. The fractal characteristic of the crack front was analyzed by measuring its fractal dimension and roughness exponent at the same time. The experimental results show that the irregularity of the crack front was partly self-affine.
关键词:
佟媛媛
,
华勤
上海金属
doi:10.3969/j.issn.1001-7208.2010.03.011
运用热分析技术研究了冷却曲线特征值与319铝合金中化学成分之间的关系,并进行回归分析.结果表明,在不考虑工艺因素的情况下,试样的硅含量与α-Al枝晶生长回升温度TαDENG之间的相关性最大,相关系数r为-0.65,以硅含量可预测α-Al枝晶生长回升温度.在浇注过程中,冷却速度与α-Al枝晶生长回升温度TαDENG密切相关,相关系数为r=-0.72.在相同的冷却条件下,铝合金的浇注温度和浇注量对冷却速度有明显的影响,因此,可以通过调整浇注温度和浇注量,控制铝合金的冷却速度,进而也可预测铝合金中α-Al枝晶生长回升温度TαDENG.
关键词:
319铝合金
,
热分析
,
特征值
,
浇注工艺
Nuclear Engineering and Design
Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the two alloys. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM), the inclusions were analyzed by an energy dispersive spectroscopy (EDS), and the surface roughness was also measured by surface roughness tester to illustrate the evolution of erosion process. The results show that the cumulative mass loss of CE of Inconel 625 is about 1/6 that of Inconel 600 and the CE incubation period of the Inconel 625 is 4 times as long as that of the Inconel 600. The micro-morphology evolution of CE process illustrates that the twinning and hardness of the Inconel 625 plays a significant role in CE. In addition, the cumulative mass loss of JIE of Inconel 625 is about 2/3 that of Inconel 600 at impacting angle of 90 degrees, and almost equal to that of the Inconel 600 at impacting angle of 30 degrees. Overall, the resistance to CE and JIE of Inconel 625 is much superior to that of Inconel 600. (C) 2010 Elsevier By. All rights reserved.
关键词:
stress-corrosion cracking;aluminide intermetallic alloys;high-purity;water;mechanical-properties;crevice corrosion;solid particles;wear;behavior;microstructure;deformation;steam
Nuclear Engineering and Design
A composite coating was deposited on Inconel 600 substrate by cold spray method using pure Ni powder (60 wt.%) blended with alpha-Al(2)O(3) (40 wt.%) as feedstock. It is expected to be applied to repair the bellows eroded by the liquid droplet erosion (LDE). Microstructure of the coating was observed using optical microscope (OM) and scanning electron microscopy (SEM). Microhardness of the coating was determined by Vickers hardness tester. Cavitation erosion (CE) experiments were carried out in the distilled water. Jet impingement erosion (JIE) experiments were performed in slurry containing 1 wt.% quartz particle with the flow velocity of 15 m/s at impingement angles of 30 degrees, 60 degrees and 90 degrees, respectively. Cumulative mass loss vs. testing time was used to evaluate the erosion rate of the coating. The erosion mechanism was analyzed by OM, SEM, X-ray diffraction (XRD) and the microhardness measurement. The results show that the composite coating has compact microstructure and relatively high hardness. The resistance to CE of the coating is not as good as that of Inconel 600 substrate due to the weak bonds of the Al(2)O(3) particles. However, the results of the JIE test indicate that the slurry erosion resistance of the coating is better than that of Inconel 600 at the impact angles of 30 degrees and 60 degrees, but not at the normal impact angle. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
large powder particles;composite coatings;slurry erosion;kinetic;spray;liquid impact;alloy;microstructure;steels;deposition;resistance
Journal of Applied Physics
Motivated by the recent experimental fabrication of half-metallic MnSb and CrSb thin films with metastable zinc-blende structure [Aldous et al. Phys. Rev. B 85, 060403(R) (2012); Deng et al. J. Appl. Phys. 99, 093902 (2006)], we investigate the structural, electronic, and magnetic properties of TiSb in both ground-state NiAs and metastable zinc-blende phases by using the first-principles calculations. It is shown that the ground-state NiAs phase is metallic and nonmagnetic, but the metastable zinc-blende phase exhibits half-metallic ferromagnetism with a magnetic moment of 1.00 mu(B) per formula unit. We also reveal that the half-metallicity in bulk ZB TiSb is lost at the Sb-terminated (001) surface due to the appearance of surface states within the gap of the minority-spin channel, but the Ti-terminated (001) surface retains the bulk half-metallicity, which makes ZB TiSb a promising candidate for the possible epitaxial growth of half-metallic thin films or multilayers on semiconductor substrates for spintronic applications. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4739744]
关键词:
room-temperature ferromagnetism;molecular-beam epitaxy;crsb;cras;spintronics;state;mnas
涂娜
,
江向平
,
李小红
,
傅小龙
,
杨帆
人工晶体学报
采用传统固相法制备了(1-x)Bi4Ti3 O12-xSrBi2 Nb2 O9(BIT-SBN,x=0,0.025,0.050,0.100,0.150,0.200)铋层状无铅压电陶瓷.系统研究了SrBi2 Nb2 O9掺杂对Bi4Ti3 O12基陶瓷物相结构、微观结构以及jie电性能的影响.结果表明:所有陶瓷样品均为单一的铋层状结构;当SBN掺量为0.100时,样品具有最佳的电性能:d33=21 pC/N,相对密度ρ =98.1％,机电耦合系数kp=8.26％,εr=220,介电损耗tanδ =0.29％,剩余极化强度Pr=9.128 μC/cm2,Tc=594℃.同时,SBN的引入增强了样品的抗老化性和热稳定性.
关键词:
Bi4Ti3O12
,
SrBi2Nb2O9
,
铋层状
,
铁电陶瓷
,
介电性能
