期刊文献+
共找到3,827篇文章
< 1 2 192 >
每页显示 20 50 100
Correlation Between Crystal Rotation and Redundant Shear Strain in Rolled Single Crystals: A Crystal Plasticity FE Analysis
1
作者 Hui Wang Cheng Lu +3 位作者 Kiet Tieu Yu Liu Rui Wang Jintao Li 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第4期452-460,共9页
The correlation between crystal rotation and redundant shear strain in rolled single crystals was investigated by using the crystal plasticity finite element(CPFE) model in this paper. The deformation in aluminium sin... The correlation between crystal rotation and redundant shear strain in rolled single crystals was investigated by using the crystal plasticity finite element(CPFE) model in this paper. The deformation in aluminium single crystals of four representative orientations(rotated-Cube, Goss, Copper, and Brass) after rolling and plain strain compression was simulated, and the predictions have been validated by the experimental observations. In the rotated-Cube and Goss, the redundant shear strain and crystal rotation were in the same pattern, alternating along the thickness, while the relation between them was not obvious for the Copper and Brass due to their asymmetrical distributions of activated slip systems. The relations between slip system activation, crystal rotation, and shear strain were investigated based on the CPFE model, and the correlation between shear strain and crystal rotation has been built. 展开更多
关键词 CRYSTAL PLASTICITY finite element Single CRYSTAL CRYSTAL ROTATION Shear strain Orientation stability
A reduced-order method for parameter identification of a crystal plasticity model considering crystal symmetry
2
作者 HAN ShiWei YANG XiaoGuang +1 位作者 SHI DuoQi HUANG Jia 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第3期373-387,共15页
The focus of this paper is to identify the material parameters of a crystal plasticity model for Ni-base single crystal superalloys.To facilitate the stepwise calibration of the multistage flow rules, further decoupli... The focus of this paper is to identify the material parameters of a crystal plasticity model for Ni-base single crystal superalloys.To facilitate the stepwise calibration of the multistage flow rules, further decoupling and simplification are implemented without compromising its simulating capability. Reduced-order kinematics in crystal plasticity, which only comprise scalar components instead of their original tensors, are derived by considering the crystal symmetry and uniaxial loading condition. The relationships between components in elastic and plastic deformation gradient are established by explicitly accounting the control quantities, which is overall load in stress-controlled creep tests or displacement of gauge section in strain-controlled experiments,respectively. In addition, their approximate forms are also given by neglecting both elastic changes in volume and section area. A new objective function based on the shortest distance was introduced to correlate data from the simulations and experiments, and an integrated optimization process without finite element computation was developed into a commercial software package.Parameters in the crystal plasticity model are successfully calibrated by the efficient reduced-order method from the experimental data in such a sequence as: elastic, plastic, primary stage and secondary to tertiary stages creep laws. The multistage weak coupling flow rules can significantly reduce the non-uniqueness of the optimal solution under the circumstance of excessive parameters but insufficient experimental data. Finally, the optimized results with the reduced-order method have been validated by the finite element method. 展开更多
关键词 reduced-order CRYSTAL PLASTICITY PARAMETER identification finite DEFORMATION single CRYSTAL CRYSTAL SYMMETRY
软轴单晶炉晶体生长的固有干扰因素分析 预览
3
作者 张志坚 池蓉 罗凤灵 《云南冶金》 2019年第5期65-71,共7页
随着半导体产业技术发展,提高单晶材料生长的成晶率和晶体内在品质越来越重要。国内目前普遍采用软轴单晶炉进行锗、硅单晶棒生产,软轴单晶炉相对硬轴单晶炉具有结构紧凑,运行可靠、设备成本低等的优点,但是软轴单晶炉由于软轴系统类似... 随着半导体产业技术发展,提高单晶材料生长的成晶率和晶体内在品质越来越重要。国内目前普遍采用软轴单晶炉进行锗、硅单晶棒生产,软轴单晶炉相对硬轴单晶炉具有结构紧凑,运行可靠、设备成本低等的优点,但是软轴单晶炉由于软轴系统类似于单摆和弹簧振子的结构特点,容易产生固有共振干扰,存在对晶体品质不利的影响因素。对这些干扰因素、解决措施进行了简要分析和讨论。 展开更多
关键词 单晶 软轴单晶炉 固有干扰
在线阅读 免费下载
IN718单晶微柱体锯齿状变形的晶体塑性分析 预览
4
作者 张旭 祝明昊 +1 位作者 张万瑞 尚福林 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2019年第4期46-50,共5页
为较为准确可靠地预测IN718合金服役于各种复杂工况下的力学响应,开展了位移控制条件下微米尺寸IN718合金单晶锯齿状变形行为的理论建模研究工作.首先,基于微压缩测试的实验观察,建立了能够较为真实反映位移控制下晶体材料变形的'... 为较为准确可靠地预测IN718合金服役于各种复杂工况下的力学响应,开展了位移控制条件下微米尺寸IN718合金单晶锯齿状变形行为的理论建模研究工作.首先,基于微压缩测试的实验观察,建立了能够较为真实反映位移控制下晶体材料变形的'变形块-弹簧'力学分析模型.进而,通过分析晶体材料锯齿状变形行为中的应变强化、流动法则、加卸载准则以及应变突变判据等建模要素,构建了描述该行为的连续化晶体塑性本构理论模型之后,应用该模型分别研究了单滑移与双滑移取向的IN718合金单晶微柱体的轴向压缩响应,并与对应微压缩实验结果进行了比较.研究结果表明,基于上述理论模型预测的IN718单晶柱体轴向力学响应出现了加载、卸载以及应变突变3种变形方式,呈现出明显的锯齿状变形行为,与对应实验测试结果具有很好的吻合性.基于连续介质框架构建的微尺度锯齿状塑性本构模型,可为经典的连续化晶体塑性理论在亚微米尺度领域的发展提供有力理论支撑. 展开更多
关键词 IN718合金 微柱体 单晶 锯齿状行为 晶体塑性
在线阅读 免费下载
Scalable and ultrafast epitaxial growth of single-crystal graphene wafers for electrically tunable liquid-crystal microlens arrays
5
作者 Bing Deng Zhaowei Xin +18 位作者 Ruiwen Xue Shishu Zhang Xiaozhi Xu Jing Gao Jilin Tang Yue Qi Yani Wang Yan Zhao Luzhao Sun Huihui Wang Kaihui Liu Mark H. Rummeli Lu-Tao Weng Zhengtang Luo Lianming Tong Xinyu Zhang Changsheng Xie Zhongfan Liu Hailin Peng 《科学通报:英文版》 SCIE EI CSCD 2019年第10期659-668,共10页
The scalable growth of wafer-sized single-crystal graphene in an energy-efficient manner and compatible with wafer process is critical for the killer applications of graphene in high-performance electronics and optoel... The scalable growth of wafer-sized single-crystal graphene in an energy-efficient manner and compatible with wafer process is critical for the killer applications of graphene in high-performance electronics and optoelectronics. Here, ultrafast epitaxial growth of single-crystal graphene wafers is realized on singlecrystal Cu90Ni10(1 1 1) thin films fabricated by a tailored two-step magnetron sputtering and recrystallization process. The minor nickel(Ni) content greatly enhances the catalytic activity of Cu, rendering the growth of a 4 in. single-crystal monolayer graphene wafer in 10 min on Cu90Ni10(1 1 1), 50 folds faster than graphene growth on Cu(1 1 1). Through the carbon isotope labeling experiments, graphene growth on Cu90Ni10(1 1 1) is proved to be exclusively surface-reaction dominated, which is ascribed to the Cu surface enrichment in the Cu Ni alloy, as indicated by element in-depth profile. One of the best benefits of our protocol is the compatibility with wafer process and excellent scalability. A pilot-scale chemical vapor deposition(CVD) system is designed and built for the mass production of single-crystal graphene wafers, with productivity of 25 pieces in one process cycle. Furthermore, we demonstrate the application of single-crystal graphene in electrically controlled liquid-crystal microlens arrays(LCMLA), which exhibit highly tunable focal lengths near 2 mm under small driving voltages. By integration of the graphene based LCMLA and a CMOS sensor, a prototype camera is proposed that is available for simultaneous light-field and light intensity imaging. The single-crystal graphene wafers could hold great promising for highperformance electronics and optoelectronics that are compatible with wafer process. 展开更多
关键词 GRAPHENE ULTRAFAST growth CuNi(1 1 1)thin film Single CRYSTAL wafer Liquid CRYSTAL MICROLENS arrays
Molecular dynamics simulation of chip formation mechanism in single-crystal nickel nanomachining
6
作者 ZHU ZongXiao PENG Bin +3 位作者 FENG RuiCheng WANG LinJun JIAO Shi DONG Yun 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第11期1916-1929,共14页
Nanometric machining simulations of single-crystal nickel were performed using molecular dynamics.The atomic displacement vector method was applied to study the relationship between defect displacement vectors and the... Nanometric machining simulations of single-crystal nickel were performed using molecular dynamics.The atomic displacement vector method was applied to study the relationship between defect displacement vectors and the crystal slip system during different deformation stages as well as the displacement trend characteristics of workpiece atoms under different deformations.The arrangement characteristics of atoms in the machining region,relative density of atoms at different machining zones,and proportion of different atoms were investigated in detail.In addition,the atom shunt phenomenon was observed by studying the displacement trend of the atoms adjacent to the machining tool,and a method for determining the location of the shunt point was determined.Moreover,direct evidence of crystal transition caused by temperature was obtained.The effects of machining depth on workpiece damage,surface flatness,and workpiece temperature were investigated.With increasing machining depth,the chip gradually changed from spherical to strip-shaped,the damage depth of workpiece gradually increased,but the atomic arrangement of the machined surface became neater.Simultaneously,the dislocation reaction of subsurface defects was studied,and the rationality of the reaction was analyzed using an energy criterion.Furthermore,the overall temperature of the workpiece increased,but the temperature of the chip part gradually decreased. 展开更多
关键词 molecular dynamics simulation single crystal nickel atomic displacement vector crystal slip system shunt point
单晶LiNi0.6Co0.2Mn0.199Zr0.001O2材料的合成及性能改善研究 预览
7
作者 李文升 许国峰 +1 位作者 刘攀 樊勇利 《电源技术》 CAS 北大核心 2019年第7期1100-1103,共4页
利用共沉淀反应合成Ni0.6Co0.2Mn0.199Zr0.001(OH)2前驱体,配锂经900℃高温烧结12h制得平均粒径为3~5 μm的Li Ni0.6Co0.2M n0.199Zr0.001O2单晶材料.经喷雾干燥及450℃高温分解4h制得Al2O3包覆单晶LiN i0.6Co0.2Mn0.199Zr0.001O2复合材... 利用共沉淀反应合成Ni0.6Co0.2Mn0.199Zr0.001(OH)2前驱体,配锂经900℃高温烧结12h制得平均粒径为3~5 μm的Li Ni0.6Co0.2M n0.199Zr0.001O2单晶材料.经喷雾干燥及450℃高温分解4h制得Al2O3包覆单晶LiN i0.6Co0.2Mn0.199Zr0.001O2复合材料.利用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、透射电子显微镜法(TEM)、电感耦合等离子体光谱分析法(ICP)对材料进行分析,结果表明:Al2O3以非晶态包覆于颗粒表面且不改变材料的晶体结构与形貌特征;包覆0.25%(质量分数)Al2O3材料首次放电比容量为163.4 mAh/g,0.2 C下循环100次后容量保持率为98.69%,5 C/0.2 C容量保持率为78.6%;包覆Al2O3有效降低了电极阻抗,抑制了过渡金属离子溶解,包覆0.25% Al2O3的材料阻抗最小,电解液中过渡金属离子含量也最低.综合性能的提升证明Al2O3包覆层能抑制活性物质与电解液界面副反应,提高材料的结构稳定性. 展开更多
关键词 单晶 晶体结构 电性能 阻抗
在线阅读 免费下载
New dammarane-type saponins from the leaves of Panax notoginseng
8
作者 Jiwu Huang Chuangjun Li +5 位作者 Junzi Cao Jie Ma Yiqian Du Xinyi Liu Jingzhi Yang Dongming Zhang 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第2期447-450,共4页
Two new triterpenoid saponins named notoginsenoside-Ng3(1) and notoginsenoside-Ng4(2) along with three known saponins (3-5), were isolated from a water extract of the leaves of Panax notoginseng. Their structures were... Two new triterpenoid saponins named notoginsenoside-Ng3(1) and notoginsenoside-Ng4(2) along with three known saponins (3-5), were isolated from a water extract of the leaves of Panax notoginseng. Their structures were elucidated by HRESIMS, NMR, X-ray techniques and acid hydrolysis. Moreover,compound 2 was characterized with the conjugated double bonds side-chain, which was rarely found in this plant. The absolute configuration of notoginsenoside Fa (3) with five sugars was confirmed by the single-crystal X-ray diffraction for the first time. Acetylcholinesterase inhibitory activity experiments were also conducted, all the isolated saponins showed weak inhibitory activities in the final concentration of 0.16 mmol/L. 展开更多
关键词 PANAX notoginseng Notoginsenoside-Ng3 Notoginsenoside-Ng4 SINGLE-CRYSTAL X-ray diffraction ACETYLCHOLINESTERASE inhibitory activity
Controlled fabrication, lasing behavior and excitonic recombination dynamics in single crystal CH3NH3PbBr3 perovskite cuboids
9
作者 Fangtao Li Junfeng Lu +7 位作者 Qinglin Zhang Dengfeng Peng Zheng Yang Qian Xu Caofeng Pan Anlian Pan Tianfeng Li Rongming Wang 《科学通报:英文版》 SCIE EI CSCD 2019年第10期698-704,共7页
As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. T... As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with ID and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite w让h different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MSMAPbBr3), via solvothermal method. Furthermore, the as-prepared *crystals excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoiuminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices. 展开更多
关键词 Lead HALIDE PEROVSKITE SOLVOTHERMAL method Single crystal CUBOID LASING TRPL
Influences of Re on low-cycle fatigue behaviors of single crystal superalloys at intermediate temperature
10
作者 Liu Liu Jie Meng +4 位作者 Jinlai Liu Mingke Zou Haifeng Zhang Xudong Sun Yizhou Zhou 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第9期1917-1924,共8页
Low-cycle fatigue behaviors of Ni-base single crystal superalloys containing different Re contents have been investigated at 760℃. During heat treatment. Reretards γ phases coarsening and equalizes the distribution ... Low-cycle fatigue behaviors of Ni-base single crystal superalloys containing different Re contents have been investigated at 760℃. During heat treatment. Reretards γ phases coarsening and equalizes the distribution of γ' phases. As Re content increases, fatigue life increases and slip bands distribute more inhomogeneously. Moreover, adding Re not only reduces stacking fault energy of the matrix, but also promotes the element segregation to increase the lattice misfit. However, the larger lattice misfit does not lead to the formation of dislocation networks, but which activates dislocation movement and promotes dislocations cross-slip and climbing movement under high temperature and applied stress. On the other hand, with the addition of Re, cyclic deformation behaviors change from cyclic hardening to cyclic stability, mainly depending on a transformation of deformation mechanisms from slip bands cutting through γ and γ' phases to stacking faults shearing. 展开更多
关键词 Single crystal SUPERALLOYS Low-cycle FATIGUE DEFORMATION BEHAVIORS DEFORMATION mechanisms
3-酮-2硫杂-5-氮杂双环[2.2.1]庚烷-5-酸4-硝基苄酯在不同溶剂中溶解度测定与关联 预览
11
作者 王彦飞 刘宗京 赵晓昱 《中国抗生素杂志》 CAS CSCD 2019年第7期845-849,共5页
采用平衡法测定了283.15~353.15K范围内美罗培南中间体(3-酮-2硫杂-5-氮杂双环[2.2.1]庚烷-5-酸4-硝基苄酯)在乙酸乙酯、乙酸甲酯、正丙醇和丙酮溶液中的溶解度,并用Apelblat模型、经验多项式模型、λ-h模型对实验数据进行关联。结果证... 采用平衡法测定了283.15~353.15K范围内美罗培南中间体(3-酮-2硫杂-5-氮杂双环[2.2.1]庚烷-5-酸4-硝基苄酯)在乙酸乙酯、乙酸甲酯、正丙醇和丙酮溶液中的溶解度,并用Apelblat模型、经验多项式模型、λ-h模型对实验数据进行关联。结果证明:3-酮-2硫杂-5-氮杂双环[2.2.1]庚烷-5-酸4-硝基苄酯溶解度随着温度的升高而增加。Apelblat模型平均相对误差小于8%,经验模型平均相对误差小于10%,λ-h方程拟合平均相对误差小于2%,效果最佳。应用单晶衍射仪首次确定了晶体属正交晶系,空间群P21,晶胞参数a=7.1630nm、b=9.1713nm、c=20.998nm、α=90°、β=90°和γ=90°。 展开更多
关键词 美罗培南中间体 单晶 溶解度 参数估值 结晶 模型
在线阅读 下载PDF
化学气相沉积法在液态金属上快速生长石墨烯单晶
12
作者 郑舒婷 曾梦琪 +4 位作者 曹慧 张涛 高晓雯 肖遥 付磊 《中国科学:材料科学(英文版)》 CSCD 2019年第8期1087-1095,共9页
实现石墨烯大单晶的快速生长对于其未来在光电及电学器件领域的应用十分必要.目前已报道的在多晶金属衬底上生长石墨烯单晶的工作通常是通过降低前驱体供应量从而抑制成核来实现的,而这会显著降低成核以及后续生长的速度.新兴的液态金... 实现石墨烯大单晶的快速生长对于其未来在光电及电学器件领域的应用十分必要.目前已报道的在多晶金属衬底上生长石墨烯单晶的工作通常是通过降低前驱体供应量从而抑制成核来实现的,而这会显著降低成核以及后续生长的速度.新兴的液态金属催化剂具有准原子级平滑的表面和高扩散速率.理论上,液态金属是一个天然理想的基底,可同时实现低密度成核和快速生长.但截至目前,尚无工作探讨液态金属上石墨烯单晶的快速生长.在本研究中,我们成功地在液态铜表面实现了毫米级高质量石墨烯单晶的生长.液态铜中丰富的自由电子能加速石墨烯的成核,且其各向同性的平滑表面能显著抑制成核,使得成核密度较低.更重要的是,由于液态铜优异的可流动性,前驱体碳原子能实现快速扩散,这极大促进了石墨烯的生长,最高速率可达79μm s^-1.我们希望这一关于液态铜体系中石墨烯生长速率的研究能丰富研究者们对液态金属上二维材料生长行为的认知.我们也相信利用液态金属来实现石墨烯快速生长的策略能被拓展至其他二维材料,由此来促进它们在未来光电以及电学器件领域的应用. 展开更多
关键词 快速生长 液态金属 石墨烯 化学气相沉积法 单晶 成核密度 扩散速率 二维材料
新型金属钴配合物的制备及其光生电流性能研究 预览
13
作者 秦中建 李平 +4 位作者 刘肸 梁志荣 周井刚 冯冬艺 姚昱岑 《广州化工》 CAS 2019年第17期64-65,134共3页
利用水热法制备得到了一种新型金属钴配合物,单晶X-射线衍射分析结果可知,金属钴配合物为三斜晶系,空间群为Pī,a=11. 357(10)А,b=10. 028(7)А,c=14. 832(10)А,α=90°,β=91. 271(10)°,γ=90°,晶体学独立的Co(Ⅱ)离... 利用水热法制备得到了一种新型金属钴配合物,单晶X-射线衍射分析结果可知,金属钴配合物为三斜晶系,空间群为Pī,a=11. 357(10)А,b=10. 028(7)А,c=14. 832(10)А,α=90°,β=91. 271(10)°,γ=90°,晶体学独立的Co(Ⅱ)离子分别与来自6个COO^-中的6个O原子配位形成正八面体配位几何构型。在可见光的照射下,研究了该配合物的光生电流性能,结果显示:该配合物在可见光照射时产生的光生电流密度约为2. 0×10^-4m A·cm^-2,作为光电转化材料在光电器件领域具有广泛的应用价值。 展开更多
关键词 配合物 光生电流 水热法 单晶
在线阅读 下载PDF
MCrAlY涂层对单晶中γ'相消耗及TCP相生成影响的模拟研究 预览
14
作者 原慷 于月光 +1 位作者 刘建明 章德铭 《热喷涂技术》 2019年第1期23-29,共7页
高温下,MCrAlY涂层与高温合金单晶基材之间会发生元素互扩散,引起显微组织结构变化,往往造成单晶中具有析出强化作用的γ'相的消耗和对力学性能有害的拓扑密堆(Topological closed packed,TCP)相的生成。本研究采用扩散模拟计算的方... 高温下,MCrAlY涂层与高温合金单晶基材之间会发生元素互扩散,引起显微组织结构变化,往往造成单晶中具有析出强化作用的γ'相的消耗和对力学性能有害的拓扑密堆(Topological closed packed,TCP)相的生成。本研究采用扩散模拟计算的方法,设计了 6种 MCrAlY模型涂层,分析 Co、Cr、Al主元素对 DD6单晶基材显微组织的影响规律。研究结果表明,基材中γ'相消耗区在靠近涂层-基材界面处形成,该区的形成主要与 Co、Cr元素内扩散相关。基材中 TCP相则在更深位置的γ'相富集区内生成,γ'相富集区与 Al元素内扩散有关。另外,本文着重分析了涂层成分对γ'相消耗区深度及 TCP相生成含量与深度的影响。 展开更多
关键词 单晶 扩散 γ'相消耗 TCP相
在线阅读 免费下载
Evolution of interfacial dislocation networks during long term thermal aging in Ni-based single crystal superalloy DD5
15
作者 Qiang Gao Li-rong Liu +3 位作者 Xiao-hua Tang Zhi-jiang Peng Ming-jun Zhang Su-gui Tian 《中国铸造:英文版》 SCIE 2019年第1期14-22,共9页
Interfacial dislocations found in single crystal superalloys after long term thermal aging have an important effect on mechanical properties. Long term thermal aging tests for DD5 single crystal superalloy were carrie... Interfacial dislocations found in single crystal superalloys after long term thermal aging have an important effect on mechanical properties. Long term thermal aging tests for DD5 single crystal superalloy were carried out at 1,100 ℃ for 20, 100, 200, 500 and 1000 h, and then cooled by air. The effect of long term thermal aging on the dislocation networks at the γ/γ’ interfaces was investigated by FE-SEM. Results showed that during the long term thermal aging at 1,100 ℃, misfit dislocations formed firstly and then reorientation in the(001) interfacial planes occurred. Different types of square or rectangular dislocation network form by dislocation reaction. Square dislocation networks consisting of four groups of dislocations can transform into octagonal dislocation networks, and then form another square dislocation network by dislocation reaction. Rectangular dislocation networks can also transform into hexagonal dislocation networks. The interfacial dislocation networks promote the γ’ phase rafting process. The dislocation networks spacings become smaller and smaller, leading to the effective lattice misfit increasing from-0.10% to-0.32%. 展开更多
关键词 DD5 single crystal SUPERALLOY INTERFACIAL dislocations long TERM thermal AGING effective LATTICE MISFIT
钛酸锶单晶体生长工艺研究 预览
16
作者 邢彩凤 毕孝国 孙旭东 《人工晶体学报》 EI CAS 北大核心 2019年第5期817-821,共5页
使用数控焰熔法晶体生长炉生长钛酸锶单晶体,研究了气体参数、生长速度和退火工艺参数对晶体生长的影响。在氢氧比为2.5,等径生长速度保持在10mm·h^-1,生长出了直径26mm、等径长度20mm、总长40mm的钛酸锶单晶体,然后经过1550℃... 使用数控焰熔法晶体生长炉生长钛酸锶单晶体,研究了气体参数、生长速度和退火工艺参数对晶体生长的影响。在氢氧比为2.5,等径生长速度保持在10mm·h^-1,生长出了直径26mm、等径长度20mm、总长40mm的钛酸锶单晶体,然后经过1550℃×72h+1000℃×20h+600℃×24h的退火,消除钛酸锶单晶体的热应力和氧空位,得到完整的高品质的单晶体。偏光显微镜测试表明,晶体具有很好的完整性。 展开更多
关键词 数控焰熔法 单晶体 钛酸锶
在线阅读 下载PDF
高温合金单晶铸件中条纹晶缺陷的试验研究 预览 被引量:1
17
作者 马德新 王富 +1 位作者 孙洪元 徐维台 《铸造》 CAS 北大核心 2019年第6期558-566,共9页
对几种高温合金铸件中的条纹晶缺陷进行了考察和分析。发现条纹晶多出现于竖直的叶身部位,叶背多于叶盆,上部多于下部,而叶根(榫头)部位极少出现。在竖直的叶身部位的条纹晶多是纵向生长,但也有的是斜向发展。而处于水平状态的叶冠或缘... 对几种高温合金铸件中的条纹晶缺陷进行了考察和分析。发现条纹晶多出现于竖直的叶身部位,叶背多于叶盆,上部多于下部,而叶根(榫头)部位极少出现。在竖直的叶身部位的条纹晶多是纵向生长,但也有的是斜向发展。而处于水平状态的叶冠或缘板上会出现横向的条纹晶缺陷。所有条纹晶都是在基体枝晶组织的基础上形成,其基本走向由基体枝晶决定,不论这些枝晶是纵向、斜向还是横向。条纹晶不仅是是细长的线形缺陷,也可能发展为大尺度的三维缺陷,严重影响单晶铸件的质量。从铸件的微观组织来看,条纹晶实际上起源于单晶基体上断裂出来的一段枝晶。 展开更多
关键词 高温合金 单晶 定向凝固 条纹晶 晶体缺陷
在线阅读 下载PDF
Machine Learning to Instruct Single Crystal Growth by Flux Method
18
作者 姚唐适 唐岑瑶 +11 位作者 杨萌 朱恪嘉 闫大禹 伊长江 冯子力 雷和畅 李承贺 王乐 王磊 石友国 孙煜杰 丁洪 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第6期98-102,共5页
Growth of high-quality single crystals is of great significance for research of condensed matter physics. The exploration of suitable growing conditions for single crystals is expensive and time-consuming, especially ... Growth of high-quality single crystals is of great significance for research of condensed matter physics. The exploration of suitable growing conditions for single crystals is expensive and time-consuming, especially for ternary compounds because of the lack of ternary phase diagram. Here we use machine learning(ML) trained on our experimental data to predict and instruct the growth. Four kinds of ML methods, including support vector machine(SVM), decision tree, random forest and gradient boosting decision tree, are adopted. The SVM method is relatively stable and works well, with an accuracy of 81% in predicting experimental results. By comparison,the accuracy of laboratory reaches 36%. The decision tree model is also used to reveal which features will take critical roles in growing processes. 展开更多
关键词 MACHINE LEARNING Instruct Single CRYSTAL GROWTH FLUX Method
Surface treatments of CdGeAs2 single crystals
19
作者 Wei Huang Bei-Jun Zhao +4 位作者 Shi-Fu Zhu Zhi-Yu He Bao-Jun Chen Zhen Zhen Yun-Xiao Pu 《稀有金属:英文版》 SCIE EI CAS CSCD 2019年第7期683-688,共6页
The performances of second harmonic gen eration (SHG) and optical parametric oscillator (OPO) in CdGeAs2 crystal are strongly influenced by surface quality. In this paper, the surfaces of samples were treated by mecha... The performances of second harmonic gen eration (SHG) and optical parametric oscillator (OPO) in CdGeAs2 crystal are strongly influenced by surface quality. In this paper, the surfaces of samples were treated by mechanical polishing (MP), chemical polishing (CP), chemical-mechanical polishing (CMP) and CP following CMP closely (CMP + CP). Then, the surface state was characterized by optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM measurements show that an ultra-smooth surface is achieved after CMP + CP treatment and the roughness value is 0.98 nm. Meanwhile, the roughness of the surfaces treated by MP, CP and CMP are 4.53, 2.83 and 1.38 nm, respectively. By XRD rocking curves, the diffraction peak which belongs to the wafer treated by CMP + CP is the highest in intensity and best symmetrical in shape. XPS analysis indicates that Ge4+ proportions of GeO2 in total Ge content of CdGeAs2 wafers' surface after MP, CP, CMP and CMP + CP treatment are 27.6%, 42.8%, 6.1% and 30.3%, respectively. 展开更多
关键词 CdGeAs2 SINGLE CRYSTAL SURFACE TREATMENTS SURFACE ROUGHNESS
Stress dependence of the creep behaviors and mechanisms of a third-genegation Ni-based single crystal superalloy
20
作者 Quanzhao Yue Lin Liu +5 位作者 Wenchao Yang Chuang He Dejian Sun Taiwen Huang Jun Zhang Hengzhi Fu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第5期752-763,共12页
Elevated temperature creep behaviors at 1100℃ over a wide stress regime of 120-174 MPa of a thirdgeneration Ni-based single crystal superalloy were studied. With a reduced stress from 174 to 120 MPa, the creep life i... Elevated temperature creep behaviors at 1100℃ over a wide stress regime of 120-174 MPa of a thirdgeneration Ni-based single crystal superalloy were studied. With a reduced stress from 174 to 120 MPa, the creep life increased by a factor of 10.5, from 87 h to 907 h, presenting a strong stress dependence. A splitting phenomenon of the close-(about 100 nm) and sparse-(above 120 nm) spaced dislocation networks became more obvious with increasing stress. Simultaneously, ao<010> superdislocations with low mobil让ies were frequently observed under a lower stress to pass through γ precipitates by a combined slip and climb of two ao<110> superpartials or pure climb. However, ao<110> superdislocations with higher mobility were widely found under a higher stress, which directly sheared into y precipitates. Based on the calculated critical resolved shear stresses for various creep mechanisms, the favorable creep mechanism was systematically analyzed. Furthermore, combined with the microstructural evolutions during different creep stages, the dominant creep mechanism changed from the dislocation climbing to Orowan looping and precipitates shearing under a stress regime of 137-174MPa, while the dislocation dim bing mechanism was operative throughout the whole creep stage un der a stress of 120 MPa, resulting a superior creep performanee. 展开更多
关键词 NI-BASED single crystal SUPERALLOY CREEP Dislocation network Critical RESOLVED shear STRESS CREEP mechanism
上一页 1 2 192 下一页 到第
使用帮助 返回顶部 意见反馈