欢迎登录材料期刊网

材料期刊网

高级检索

  • 论文(12339)
  • 图书()
  • 专利()
  • 新闻()

(a-AB-b+b-C-b)型线型缩聚体系的分子量分布

闫福安

高分子材料科学与工程

用统计理论得到了(a-AB-b+b-C-b)型线型缩聚体系的分子量分布函数;而且双官能度单体可以控制均缩聚的平均聚合度,所得聚合物的分子量分布远比Flory分布窄.

关键词: (a-AB-b+b-C-b)型线型缩聚 , 分子量分布 , 统计理论

Phase relation in the system Sm-Co-B

Journal of Alloys and Compounds

The isothermal section at 700 degrees C in the Co-rich ternary Sm-Co-B system was determined by means of X-ray diffraction. In this range, nine ternary borides were observed: Sm3Co13B2, SmCo4B, Sm3Co11B4, Sm2Co7B3, SmCo3B2, Sm2Co14B, SmCo12B6, SmCo4B4, SmCo2B2. The first five borides are members of the homologous series Smm + nCo5m + 3nB2n formed by alternative stacking m layers of SmCo5 with n layers of SmCo3B2 along the c-axis. The compound Sm3Co13B2 was not reported in previous isothermal sections found in the literature. (C) 2000 Elsevier Science S.A. All rights reserved.

关键词: Sm-Co-B;phase diagram;magnetic-properties

Phase relation in the system Gd-Co-B

Journal of Alloys and Compounds

The isothermal section at 700 degrees C in the Go-rich ternary Gd-Co-B system was determined by means of x-ray diffraction. In this range, nine ternary borides were observed: Gd3Co13B2, GdCo4B, Gd3Co11B4, Gd(2)Go(7)B(3), GdCo3B2 Gd2Co14B, GdCo12B6, GdCo4B4, GdGo(2)B(2). This isothermal section at 700 degrees C is similar to other isothermal sections found in the literatures, but they do not include the compounds Gd3Co13B2 and Gd2Co14B. The first five borides are members of the homologous series Gdm + nCo5m + 3nB2n, which is formed by alternative stacking of m layers of GdCo5 with n layers of GdCo3B2 along the c-axis. (C) 2000 Elsevier Science S.A. All rights reserved.

关键词: Gd-Co-B;phase diagram;earth

Dependence of Ni, Al and B boundary concentrations on the B bulk concentration for the Ni3Al-x at.% B grain boundary

Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms

We have applied the embedded atom method (EAM). to calculate boundary concentration distributions of Ni, Al and B, and B probabilities in the "interstitial" and, the "substitutional" sites, at the Ni3Al-x at.% B (100% Ni\100% Ni) [001]/Sigma5(210)/36.87 degrees. grain boundary at the equilibrium. We propose that the bulk effects of B on the grain boundary include the positive effect on the Ni enrichment at the grain boundary, i.e. the B atoms induce Ni atoms to substitute into Al sites, the negative effect on it, i.e. the B atoms substitute into Ni sites, and the neutral effect on it, i.e. the B atoms insert into interstices in the grain boundary. Our calculations show that owing to combination of the positive effect and the negative effect, corresponding to B-enrichment increasing, the Ni-enrichment and the Al-depletion become more and more obvious, when x increases from 0.1 to 0.5. Then, corresponding to B-enrichment decreasing, the Ni-enrichment and the Al-depletion also become more and more obvious, when x decreases from 0.9 to 0.5. Thus, between low (x = 0.1) and high (x = 0.9) B bulk concentrations, there is a B bulk concentration (x = 0.5), at which the Ni-enrichment and the Al-depletion become the most obvious, even if Ni is approximately saturated. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: computer-simulation;boron;segregation;fracture;metals;alloys

第27卷B辑作者索引

金属学报

Volu扣ne 27SeriesB1991AUTHOR INDEX CCAO Guanghan(曹光旱)············……6一B科6CAo weijie(曹卫恋)..················……5一B32oCAO Yilin(曹益林)··················……6一B443CHANG Xin(常听)···············……1一B48CHE Guang邻n(车广灿)·············一6一B科0CHEN Erbao(陈二保)···············……6一B410CHEN Jia....

关键词:

Decomposition of B4C and magnetic properties of Nd-Fe-(B,C) alloys synthesized by mechanical alloying

Journal of Alloys and Compounds

Nd-Fe-(B.C) alloys have been synthesized by mechanical alloying and subsequent heat-treatment, with B4C as one of the starting materials. It is found that when the pure B4C is milled alone, it proves difficult to decompose. When the B4C compound is milled with Nd and Fe, the complete decomposition of B4C and the formation of Nd2Fe14(B,C) phase is observed. Furthermore, the competition between B and C atoms for entering the Nd2Fe14B lattice. the effects of the B4C content on the structure and the magnetic properties of Nd2Fe14(B,C)-based alloys are investigated. A coercivity as high as 18.3 kOe and the maximum energy product of 10.4 MGOe have been achieved for the Nd-Fe-(B,C) alloys. (c) 2005 Elsevier B.V. All rights reserved.

关键词: permanent magnets;mechanical alloying;fe-c alloys;permanent-magnets;r2fe14c;nd

Effect of P and B on the creep behavior of alloy 718

Materials Letters

The effects of P and B on the creep behavior of 718 alloys are discussed in this paper. The result implies that P and B have little effect on the gamma" and gamma' phases of the alloy, but they can enhance the grain boundary strength by segregating there, which can be of beneficial to the higher creep properties. P also may increase the grains strength through solid solution. The beneficial effect of P and B were presented in both standard IN718 alloy and DA718 alloy. Adding P and B together does a better work than adding P alone. (c) 2006 Elsevier B.V. All rights reserved.

关键词: P and B;718 alloy;creep;grain boundaries;heat treatment;stress rupture;phosphorus;superalloy;boron

Orientation relationships between TiB (B27), B2, and Ti(3)Al phases

Journal of Materials Research

The orientation relationships among TiB (B27), B2, and Ti(3)Al phases have been investigated by transmission electron microscopy. By using the composite selected-area electron diffraction technique, the orientation relationship between TiB (B27) and B2 was determined to be [100](TiB)parallel to[00](B2), (001)(TiB)parallel to(010)(B2); and that between TiB (B27) and Ti(3)Al was [010](TiB)parallel to[1120](Ti3Al), (001)(TiB)parallel to(0001)(Ti3Al). These orientation relationships have been predicted precisely by the method of coincidence of reciprocal lattice points.

关键词: tial-based alloys;grain-refinement;titanium aluminides;boron;addition;al;microstructure;intermetallics;evolution;system

THREE-DIMENSIONAL TOPOLOGICAL ANALYSIS OF Nd-Fe-B AND Pr-Fe-B PHASE DIAGRAMS

LIU Guoquan XU Pingguo University of Science and Technology Beijing , Beijing , China professor , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

With the aid of 3-dimensional topological analysis methodology,relationships among phage regions on the isothermal section of the Nd-Fe-B phase diagram at 1000℃ and those on vertical sections of the Pr-Fe-B phase diagram passing through Pr_2 Fe_(14)B point have been re-discussed and modified.

关键词: Nd-Fe-B , null , null , null , null

CdZnTe材料(111)B和(211)B面上位错腐蚀坑密度的差异

顾惠明 , 杨建荣 , 陈新强 , 何力

人工晶体学报 doi:10.3969/j.issn.1000-985X.1999.02.012

用Everson腐蚀剂对CdZnTe晶体(111)B和(211)B面上的位错进行了腐蚀和观察,发现(111)B面上的腐蚀坑密度(EPD)值明显高于(211)B面上的EPD值,(111)B面上的EPD值与双晶衍射半峰宽有明显的依赖关系,(111)B面上的FWHM值随EPD的增加而增加.而(211)B面上的EPD则与材料的双晶衍射半峰宽无关.研究结果表明,用Everson腐蚀剂得到的EPD参数依赖于材料的晶体取向,在两种常用的晶体学取向中,(111)B面上得到的EPD能较为正确的反映CdZnTe材料中的位错密度.

关键词: CdZnTe , 位错 , 腐蚀法 , 布里奇曼法 , 衬底材料

  • 首页
  • 上一页
  • 1
  • 2
  • 3
  • 4
  • 5
  • 下一页
  • 末页
  • 共1234页
  • 跳转 Go

出版年份

刊物分类

相关作者

相关热词