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101.
研究一维正方准晶平行于准周期方向的直位错的平面弹性问题.在导出应力分量的复表示的基础上,利用广义复变方法,求解了一维正方准晶中两个平行的无限长直位错间的相互作用力问题,给出了相互作用力的解析表达式. 相似文献
102.
High temperature annealing was performed on upgraded metallurgical grade multicrystalline silicon (UMG multi-Si) wafers with a purity of 99.999%. The samples were mechanically polished and chemically etched, and then the microstructures were observed by a scanning electron microscope (SEM). The minority carrier lifetime and resistivity of the samples were measured using microwave photoconductance decay and four-point probe techniques, respectively. The results show that the electrical properties of the samples decrease rather than increase as the annealing temperature increases, while the number of dislocations in bulk Si reduced or even disappeared after annealing for 6 hours at 1100–1400°C. It is considered that the structural microdefects induced by the high concentration of metal impurities (including interstitial or substitutional impurities and nanoscale precipitates) determine the minority carrier recombination activity and thus the electrical properties of UMG multi-Si wafers rather than dislocations in bulk Si. 相似文献
103.
Jia Xiao Ming Li Jian-ping Liang Li Jiang De-jun Wang Xiang-xi Ye Ze-zhong Chen Na-xiu Wang Zhi-jun Li 《矿物冶金与材料学报》2021,28(11):1811-1820
An explosion-welded technology was induced to manufacture the GH3535/316H bimetallic plates to provide a more cost-effective structural material for ultrahigh temperature, molten salt thermal storage systems. The microstructure of the bonding interfaces were extensively investigated by scanning electron microscopy, energy dispersive spectrometry, and an electron probe microanalyzer. The bonding interface possessed a periodic, wavy morphology and was adorned by peninsula- or island-like transition zones. At higher magnification, a matrix recrystallization region, fine grain region, columnar grain region, equiaxed grain region, and shrinkage porosity were observed in the transition zones and surrounding area. Electron backscattered diffraction demonstrated that the strain in the recrystallization region of the GH3535 matrix and transition zone was less than the substrate. Strain concentration occurred at the interface and the solidification defects in the transition zone. The dislocation substructure in 316H near the interface was characterized by electron channeling contrast imaging. A dislocation network was formed in the grains of 316H. The microhardness decreased as the distance from the welding interface increased and the lowest hardness was inside the transition zone. 相似文献
104.
位错是晶体中的一种线型缺陷,它在晶体中普遍存在,不仅影响着晶体的力学强度,而且对固体的许多物理性质均有重要影响.为了能形象地理解位错的基本性质,本文以刃型位错作为研究算例,通过编写Visual C++程序,成功地实现了对刃型位错原子动态图象及其应力场分量的计算机模拟,并详细阐述了程序设计原理和实现方法.本文的编程思想和通过定性及定量分析得出的结论对深入研究位错的特性提供了很好的参考思路. 相似文献
105.
106.
目的 探讨全髋关节置换术治疗成人先天性髋关节脱位伴骨性关节炎的疗效。方法 2000年6月~2006年3月,对24例(30髋)成人先天性髋关节脱位伴骨性关节炎患者进行了全髋关节置换。其中双侧6例,单侧18例。年龄45~67岁。并对其疗效进行分析,疗效评价根据Harris评分而分为优、良、可、差四级。结果 所有患者手术顺利进行,术后伤口均一期愈合。术后5月,患者均能下地行走,生活自理且恢复日常工作。平均Harris评分由术前的(46.2±8.7)分恢复到术后1年的(90.5±7.4)分,术后与术前Harris评分比较t=17.6714(P〈0.05),其中评定为优13髋、良14髋、可2髋、差1髋,术后优良率达90.00%。术后髋关节脱位1例。本组病例无肺栓塞、深静脉血栓形成、感染等并发症发生。随访6~49月,X线检查示假体位置良好。结论 全髋关节置换术是治疗成人先天性髋关节脱位伴骨性关节炎的一种有效方法。 相似文献
107.
108.
表征晶体中位错的Peierls-Nabarro(PN)模型的控制方程十分复杂,求解往往直接给出解答,而没有给出求解过程,这为PN模型的应用带来了困难。针对Peierls-Nabarro模型的这一局限性,提出一种新的方法分析简单立方晶体中混合位错的成核过程。该方法将位错密度场表示成第一类Chebyshev多项式的形式,而滑移面上的剪应力表示成三角级数的形式,得到了新的控制方程,最后运用Newton-Raphson法对新的控制方程进行求解。计算结果表明,本文提出的方法对于分析简单立方晶体中混合位错的成核过程具有简单、精确的特点。 相似文献
109.
目的探讨锁骨钩钢板内固定治疗肩锁关节脱位和锁骨远端骨折的疗效。方法自2005年7月至2008年7月用锁骨钩钢板内固定治疗肩锁关节脱位和锁骨远端骨折共24例,其中肩锁关节脱位11例,锁骨远端骨折13例。术后早期进行功能锻炼。结果所有患者均获得良好复位和固定,术后X线评估复位率达100%。术后8-12月取出内固定后,关节功能恢复良好率100%,无骨折及脱位再发生。采用Karlsson分级标准进行疗效评定:A级21例,B级3例,无C级。结论锁骨钩钢板内固定治疗肩锁关节脱位和锁骨远端骨折操作简易、复位满意、患者恢复快,效果良好。 相似文献
110.
Effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging 下载免费PDF全文
The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation (GND) density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 μm×80 μm separate into fine equiaxed grains of 20 μm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83×1013 to 4.40×1011 m-2 in grains with 〈111〉 fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone (PFZ) are facilitated due to the eroding activity of the Graff etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference. 相似文献