排序方式: 共有74条查询结果,搜索用时 31 毫秒
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WANG Shuncai LI Chunzhi YAN Minggao Institute of Aeronautical Materials Beijing China BIAN Weimin Northeast Institute of Technology Shenyang China WANG Shuncai Graduated Student Institute of Aeronautical Materials Beijing China 《金属学报(英文版)》1990,3(2):104-109
X-ray microanalysis,convergent beam electron diffraction(CBD)and selected area electrondiffraction(SAD)studies on the structures and compositions of the constituent phases in2024 series Al alloys have been conducted.Partial substitution of alloying elements is found tooccur in all the constituent phases,which cause small deviations from the stoichiometric com-positions reported in these ternary compounds.The dominant phase is α-Al_(12)(FeMn)_3Si whichhas a body center cubic crystal structure with the Im■ space group and a=1.25 nm.The nextdominant phase is Cu_2FeAl_7 which has a primitive tetragonal crystal structure with theP4/mnc space group and a=0.6336 nm,c=1.487 nm.The minor phase is α'-Al_(12)Fe_3Si hav-ing α primitive cubic crystal structure with the Pm■ space group and α=1.27 nm. 相似文献
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LI Chunzhi WANG Shuncai JIN Yan Institute of Aeronautical Materials Beijing Laboratory of Atomic Imaging of Solids Institute of Metal Research Academia Sinica Shenyang China 《金属学报(英文版)》1992,5(4):227-230
The dispersoid phase Al_(20)Cu_2Mn_3 in a 2024 Al alloy is commonly composed of twins,An ob-servation of corresponding high resolution image shows that the twin boundary plane is a glideplane other than mirror one.Two neighbouring components of twins are not symmetry of re-flection or rotation,but of glide reflection.The“diamond”glide plane is(101)and the glidevector is(1/4)(-).Components of twins in the phase take shape of prism with thelongitudinal edge being parallel to[010]and side faces being{101}and{100}. 相似文献
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WU Yilei QIANG Jun WANG Shuncai LI Yongwei GUO Bichao LIU Bocao Institute of Aeronautical Materials Beijing Engineer Institute of Aeronautical Materials Beijing China 《金属学报(英文版)》1993,6(1):26-29
The fracture mechanism for Al-2.5Li-1.3Cu-0.9Mg-0.13Zr alloy is quite different fromundergone various regimes of heat treatment.With the decrease of solution temperature andthe increase of aging temperature,the intergranular delamination and necking fracture on thefracture surface increase and the shearing facture decreases.Thus,the toughness of the alloymay be much improved. 相似文献
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中国城市群空间规划的历史演化与空间逻辑——基于新国家空间视角 总被引:3,自引:0,他引:3
国家空间重构中,城市群空间规划成为缓解城市间竞争和提高地区竞争力的重要工具.本文基于新国家空间理论分析中国城市群空间规划的发展历程与演变特征,结合国家空间选择性探讨城市群空间规划的空间逻辑,包括空间特征与空间效应.研究表明:首先,在不同发展阶段,中国城市群空间规划内容及其扮演的角色存在较大差异,其发展转型折射出国家空间选择性由城市尺度向区域尺度转变;其次,在社会转型宏观背景下,中国城市群空间规划是国家对区域崛起的制度回应,通过多样化策略的分层叠加,塑造了动态与嵌套的国家空间形式;最后,作为柔性的尺度重组策略,城市群空间规划以灵活与低成本的方式引导资本在特定城市群地区实现了再领域化和权力尺度重组,提高了国家空间治理能力,实现了治理模式转型.然而,中国城市群空间规划主要依赖高尺度政府自上而下的推动,存在实施效果不一致等现实矛盾,亟待强化国家空间策略的内部整合与国家空间项目的衔接. 相似文献
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房柱式及巷式矸石充填开采中,煤柱与矸石两两相隔,破碎矸石充填体处于侧限压缩状态,破碎矸石的密实程度、孔隙特征及渗透特性对于煤层瓦斯流动及地下水渗流的控制具有重要的价值。基于稳态渗透法及轴向位移控制法,利用一套自制的破碎岩体渗透试验系统,测定了破碎矸石在不同混合粒径下承压过程中的非Darcy流渗透特性,得到渗透特性(渗透率k和非Darcy流β因子)随孔隙率的变化规律。研究表明:1)雷诺数计算及孔压梯度与渗流速度关系曲线说明破碎矸石的渗透特征属于非Darcy流;2)孔隙率随着压缩位移的增加而减小,对于混合粒径试样,较小颗粒充填到较大颗粒的孔隙中,是使岩样的初始孔隙率减小的主要原因;3)在侧限压缩下,大颗粒受挤压破碎是产生0~2.5 mm粒径的原因,而渗流造成细小颗粒质量流失;4)侧限压缩下,渗透率总的趋势减小,而非Darcy流β因子增加,但在压缩过程中,渗透特性的变化趋势受颗粒粒径的影响会出现局部波折,说明破碎矸石的渗透特性与侧限压缩位移、颗粒粒径大小、压缩破碎、排列方式及孔隙结构(通道)有关。 相似文献
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