Cu—Zn—Al合金贝氏体的三个生长阶段及其精细结构研究

利用透射镜研究了Ｃｕ－Ｚｎ－Ａｌ合金贝氏体α１相在相变过程中的精细结构变化，发现贝氏体的生长经历三个阶段：初生态、中间态和退化态。初生贝氏体内不含层错亚结构，α１依台阶机制长大到一定程度后，内部出现层错；随转变进一步进行，α１内的层错结构逐渐消失，发生“过退火”，最终向平衡相转变。     

Cu－Zn－Al合金中贝氏体的扫描隧道显微镜分析

本文用扫描隧道显微镜（ＳＴＭ）在天气中研究了Ｃｕ－２７．２ｗｔ．％Ｚｎ－４．７ｗｔ．％Ａｌ合金中的贝氏体的精细结构，并与透射电镜（ＴＥＭ）及扫描电镜（ＳＥＭ）下的形态进行了比较，发现Ｃｕ－Ｚｎ－Ａｌ合金中贝氏体是由亚片条或亚单元组成，亚单元由超亚单元构成，进而为贝氏体相变机制的再认识提供了重要的实验基础，并在此基础上提出Ｃｕ－Ｚｎ－Ａｌ合金中贝氏体的形成模型。     

试样薄化导致的Cu－Al贝氏体／马氏体组织变化

加热到１１７３Ｋ的Ｃｕ－２５ａｔ；％Ａｌ合金块状试样经７２３Ｋ６０Ｓ等温淬火后其组织由片状的“羽毛状贝氏体（９Ｒ结构）和β＿１＇马氏体（１８Ｒ结构）组成。当试样被离子束轰去进一步薄化后，在足够薄的区域内生成了许多２Ｈ结构的薄片马氏体。初步分析认为该薄片马氏体形成的原因是由于贝氏体生成时在试样内留下了高的应力场，当试样薄化到一临界厚度以下时，试样区的三维约束条件松弛使试样内的应力场触发了薄片马氏体的生成。这些薄片马氏体是通过位于贝氏体界面上位错的重新启动而长大的。     

Cu－Zn－Al合金预贝氏体相变与贝氏体形核研究

本文考察了Ｃｕ－Ｚｎ－Ａｌ合金的预贝氏体相变与贝氏体形核。内耗实验表明预贝氏体相变的主要过程为溶质原子扩散、偏聚；能谱分析揭示预贝氏体相变时存在溶质偏聚引起的溶质原子贫化区与富化区；原位观察证实贝氏体于溶质原子贫化区切变形核。     

Cu─Zn─Al贝氏体及贝氏体／母相界面的精细结构

利用高分辨电镜考察了Ｃｕ－Ｚｎ－Ａｌ合金中不同生长时间的贝氏体及贝氏体／母相界面的精细结构；分析、讨论了贝氏体的有序性、贝氏体／母相界面点阵的共格性及贝氏体前沿母相中的微应变衬度。试验结果支持贝氏体相变的切变机制。     

Cu—Zn—Al合金中贝氏体的扫描隧道显微镜分析

本文用扫描隧道显微镜（ＳＴＭ）在大气中研究了Ｃｕ－２７．２ｗｔ．％Ｚｎ－４．７ｗｔ．％Ａｌ合金中的贝氏体的精细结构，并与透射电镜（ＴＥＭ）及扫描电镜（ＳＥＭ）下的形态进行了比较，发现Ｃｕ－Ｚｎ－Ａｌ合金中虫氏体是由亚片条或亚单元组成，亚单元由超亚单元构成，进而为贝氏相变机制的再认识提供了重要的实验基础，并在此基础上提出Ｃｕ－Ｚｎ－Ａｌ合金中贝氏体的形成模型。     

Al—Cu—Fe合金中的一个新相及其相关的无公度相

用电子衍射方法在Al-Cu-Fe合金系中发现了一个新相,它属四方晶系,a=b≌8.6A,c=21A。图1和2分别是其沿[001],[010]带轴拍摄的电子衍射花样。但是,不同晶粒[010]电子衍射花样上斑点间距和强度往往不同。例如图3中沿箭头所指方向看去,衍射斑点不在一条直线上。对所有衍射斑点的指标化都需要三个以上的指数。很显然,它具有一维无公度调制结构的特征。另一方面,这个特征又不同于一般。其一是从各个不同带轴的电子衍射花样上很难确定哪些衍射斑点是主衍射斑点,哪些是卫星衍射。因为在一般调制结构中,主衍射的强度都比其卫星斑点强。其二是如果不考虑强度,在图3中将     

Al－2．6Li－1．3Cu合金中T＇＿1相及其生长机制

用电子衍射方法给出了Ａｌ－２．６Ｌｉ－１．３Ｃｕ合金中Ｔ′＿１相的各种变体，并通过Ｔ′＿１相与母相的位向关系及Ｔ′＿１相的分子组成描述了Ｔ′＿２相的生长机制。Ｔ′＿１相呈不规则薄片状，通过消耗δ′相及从基体中吸取Ｃｕ原子逐渐长大。Ｔ′＿１相长大速度是各向异性的，侧面长大速度大于厚度方向的长大速度。     

Growth of Graphene-Like Structures on an Oxidized SiC Surface

Graphene-like structures were formed on an oxidized SiC (0001) surface following thermal annealing in a vacuum at high temperatures. The SiO₂/SiC structure was annealed at 1350°C in 10⁻⁵ Torr; the SiO₂ layer was vaporized, and two layer graphene-like structures were formed on the SiC surface. This method of fabricating graphene did not require an ultra-high vacuum. In the absence of the oxide layer, a film of vertical carbon nanotubes (CNTs) was grown on the SiC surface in the same temperature range at 10⁻⁵ Torr.     

Microstructure and thermal expansion properties of invar-type Cu-Zn-Al shape memory alloys

The effects of grain size, volume fraction of the α (fcc) phase in the β (bcc) matrix, and thermal stability on low thermal expansion (LTE) properties of Cu-Zn-Al shape memory (SM) alloys induced by cold rolling were investigated by dilatometry, optical microscopy, differential scanning calorimetry, and electrical conductivity measurements. The alloys with the larger grains showed a superior two-way memory (TWM) effect, wider LTE temperature intervals with excellent thermal stability under 80°C. The α+β two-phase alloys also exhibited a good combination of cold workability and LTE properties. These results suggest that the Cu-Zn-Al alloys with high electrical conductivity of about 20% International Annealed Copper Standard (%IACS) have high potential as a new class of Invar alloys that can be applied in various fields.     

过共晶Al－Si合金共生区激光表面处理

用２ｋＷ连续ＣＯ２激光对过共晶Ａｌ－１８Ｓｉ合金以不同能量密度和扫描速度进行快速熔凝处理。用扫描电镜、电子微区分析仪分析了微观结构。从计算机对Ａｌ－Ｓｉ合金ｆ－ｎｆ系统的非平衡理论计算所得的共生区及实验结果的分析可见，当能量密度和扫描速度决定的凝固条件处于共生区中部时，过共晶Ａｌ－Ｓｉ合金激光表面处理可以得到共晶间距低于２００ｎｍ的完全共晶结构。     

Macro-Sized All-Graphene 3D Structures via Layer-by-Layer Covalent Growth for Micro-to-Macro Inheritable Electrical Performances

Creating 3D-engineered macroscopic architectures while inheriting the superior properties of individual building blocks remains one of the fundamental challenges in nanotechnology. Stable covalent interconnection between micro/nanoblocks is a desired but underexplored strategy to meet the challenges, rather than current dependently-used weak physical forces or organic cross-linking, which disrupts the continuity of chemical composition and electrical properties. Herein, a novel layer-by-layer covalent growth protocol is developed to construct all-graphene macrostructures (AGM) with micro-to-macro inheritable electrical properties by laser-assisted covalent linkage of polyethersulfone-derived 3D porous graphene microblocks without introducing any catalysts, templates, and additives. Creatively, along with graphene generation and inter-layer bonding, a quality optimization process is integrated into one-step laser irradiation, which is unique and efficient for synthesizing high-crystalline graphene. With the covalently nondestructive bridge and free of non-graphene foreign phase impurities, AGM shows unprecedented electrical conductivity, especially a more than 100-fold improvement in cross-layer conductivity compared with non-covalent assembly. Furthermore, the covalent growth mechanism of AGM is clarified by molecular dynamics simulations. Finally, the application efficacy of AGM with enhanced isotropic conductivity is verified by using it as a supercapacitor electrode. This methodology enables the as-obtained AGM to possess the potential for high-performance-pursuing, multi-disciplinary, or large-scale applications.     

蓝宝石与铌合金的高温封接

通过对蓝宝石的钨金属化,实现了蓝宝石与铌合金的高温封接。实验显示钨金属化活化剂氧化钇的含量对封接件真空气密性、封接强度有着显著影响。此外,封接结构也影响着高温封接件的耐热冲击性能。     

InGaAlN四元合金的光学性质和低维结构

研究了用MOCVD方法生长lnGaAlN四元合金材料的生长规律，发现生长温度在800～880℃．其In组分随生长温度升高而降低。用变温光致发光谱和时间分辨谱研究了InGaAlN的光学性质。光致发光谱表明InGaAlN的发光强度随温度衰减规律与InGaN类似，但比GaN慢．室温下比GaN的发光强度大1个数量级以上。时间分辨光谱表明，在InGaAlN中存在低维结构的铟聚集区——在没有高温GaN中间层的InGaAlN材料中存在类似量子盘的二维铟聚集区；而在有高温GaN中间层的InGaAlN材料中存在类似量子点的零维铟聚集区。     

经济增长与电信普遍服务的五阶段模式

在引入米尔恩(Milne)提出的普遍服务五阶段模式的基础上,通过计量技术论证了我国的电信发展与经济增长存在着很强的正向关系,进而得出我国普遍服务发展的五阶段模式。从该模式可知,每个阶段的经济水平、电信水平、电信发展瓶颈都不太一样,所以我国普遍服务的目标、内容和实施措施都应该有所侧重。目前我国的普遍服务对象主要还是农村用户和中西部住宅用户,内容主要是固定电话服务,并不需要涵盖互联网接入服务,而有针对地进行补贴成为主要实施措施。而且这个阶段将会持续很长一段时闯。