Haitao YE
,
Olivier GAUDIN
,
Richard B.JACKMAN
,
null
,
null
,
null
材料科学技术（英文）
The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300℃ were reported. A wide range of chemical vapour deposition (CVD) materials were investigated, but here we concentrate on `black' diamond grown by microwave plasma enhanced CVD (MWPECVD). The Cole-Cole (Z' via Z'') plots are well fitted to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at 300℃, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF up to 300℃ suggesting that the diamond grain boundaries are dominating the conduction. At 400℃, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.
关键词:
Black diamond
,
diamond
,
Impedance
,
spectroscopy
,
Act
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
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
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
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:
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
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
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
