D.G. Ren
,
Z.Q. Li
,
X.S. Fan and J. T. Guo Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China
金属学报(英文版)
By using AP-FIM the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and antisite defects in Ni_3Al. The extent of ordering is reduced with an increase in boron content and the autisite defects are most obvious for 0.52at.K B-doped sample that has the best ductility. Some results were verified by X-ray diffraction non. The addition of boron not only influences electron environment at grain boundary but also in the interior of Ni_3Al gm ins, the latter is favorable to improve the ductility of Ni_3Al grains.
关键词:
intermetallic compound
,
null
,
null
孙银洁
,
胡胜泊
,
李秀涛
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2010.02.027
利用SEM、TEM、XPS、XRD、Raman和元素分析仪分析了M40J和T300的表面化学、物理及微观结构特征.研究发现:M40J含碳量高于T300纤维,而含氮量低于T300纤维,且表面活性基团比T300纤维低;M40J和T300碳纤维表面具有大量沟槽,前者相对长而浅,后者相对短而深;T300纤维端面皮芯结构明显,而M40J端面结构较均匀;M40J的微晶结构及取向性优于T300碳纤维.
关键词:
M40J碳纤维
,
微观结构
,
化学特征
,
物理特征
谢兰清
,
王彩霞
兵器材料科学与工程
基于重整化平均场理论,在二维空穴掺杂t-t′-J-U模型的框架下,用Gutzwiller平均场近似理论研究高温超导体的基态相图,分析了次近邻跃迁电子(t′)对电子平均双重占据数(d)的影响.发现在掺杂浓度δ≠0的掺杂Gossamer超导态,次近邻跃迁的引入使d的数值在欠掺杂浓度区增大,在过掺杂浓度区显著减少.
关键词:
高温超导体
,
相图
,
电子态
,
电子次近邻跃迁
,
双重占据
孙长征
,
宇波
,
魏进家
工程热物理学报
通过分析气相、液相、管壁之间的关系,将气液混输管道中的流型划分为五种,并总结了各流型的特点及气液相和管壁间的几何关系;在对Baker、Brill、Beggs-Brill、Taitel、段塞特征分析(SCA)等流型判别方法进行分析的基础上,提出了一种综合使用SCA、Taitel和Brill三种方法的流型判别方法 S-T-B法.经算例验证,该方法对气液两相混输的流型判断准确性较高,可以作为气液混输工艺计算过程中确定流型的方法.
关键词:
气液混输
,
流型
,
段塞特征分析法
,
S-T-B
鲁二敬
,
卢峰华
,
许鸿吉
,
谢明
,
钮旭晶
机械工程材料
通过周期浸润腐蚀试验，对比研究了S355．12W耐候钢和Q345R低合金钢在NariSOs溶液中的耐腐蚀性能，并用扫描电镜对腐蚀产物进行了观察和分析。结果表明：在相同试验条件下，S355J2W耐候钢的腐蚀速率低于Q345R钢的；S355J2W耐候钢会在表面形成黑褐色锈层，而Q345R钢表面形成橘红色易剥落的疏松锈层；S355J2W耐候钢腐蚀产物微观形貌为沿放射性方向生长的针状晶体，Q345R钢为颗粒状聚合物堆积而成，形状无规则，颗粒之间有较大的空隙。
关键词:
S355J2W耐候钢
,
周期浸润腐蚀试验
,
耐腐蚀性能
Physical Review B
The pressure effect on crystallization kinetics of amorphous solids was investigated by means of thermodynamic analysis. A model was developed to describe the nucleation process under pressure by considering the crystalline/amorphous (c/a) interface that plays a dominant role in the nucleation process. Applying the model to three types of crystallization process, polymorphous (a-Se), primary (Al89La6Ni5), and eutectic (Ni80P20), we found the calculated results can give reasonable explanations for the experimental observations. The calculation suggests that for a-Se and Ni80P20 amorphous alloy, the initial stage of nucleation is a volume expansion process due to the c/a interface formation, resulting in an increase in the nucleation work with an increment of pressure. Hence the crystallization temperature of the amorphous phase rises when a pressure is applied, while for the Al-La-Ni amorphous alloy, the nucleation barrier decreases at higher pressures. The coincidence between the calculation and the experimental results illustrates that the cia interface formation is the governing factor in the crystallization kinetics of the amorphous solids. [S0163-1829(99)03534-1].
关键词:
activation volume;nanocrystalline state;metallic glasses;diffusion;alloy;selenium;phase;se;transformations;microstructure
朱杰武
,
柳永宁
,
许雁
,
冯耀荣
机械工程材料
doi:10.3969/j.issn.1000-3738.2005.06.007
在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.
关键词:
管线钢
,
断裂韧度
,
止裂韧度
,
韧-脆断裂转变
