Xinchun CHANG
,
Jianqiang WANG
,
Nanlin SHI and Zhuangqi HU (State Key Lab. of RSA
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)Yijun DU
,
(Manufacturing Engineering Dept.
,
City University of Hong Kong
,
Kowloon
,
Hong Kong)
材料科学技术（英文）
An electrochemical sudece-treatment method has been used for modifying surface condition of large diameter CVD SiC (W core) fibers. The average tensile strength of the fibers was increased obviously from 2270.1 to 3002.9 MPa. X-ray photoelectron spectroscopy (XPS) studies on the treated fiber sudece indicate that a silicon-oxide film (primarily α-SiO2) has formed,accompanying the precipitation of amorphous carbon as the products of an anode oxidation reaction. In addition, the substantial increase of fiber strength through the electrochemical treatment may be described to the formation of oxide films and elimination of defects on the fiber surface.
关键词:
Physica B-Condensed Matter
The structural, mechanical, thermodynamics properties and phase transition of FeVSb are investigated extensively using the first principle calculations and the quasi-harmonic Debye model. From the calculated elastic constants of cubic FeVSb, some other mechanical quantities, such as bulk modulus and Poisson's ratio, are drawn. Surprisingly, it is found that almost all these mechanical quantities are larger than those of CoVSb (Bo Kong et al., J. Alloys Compd. 509 (2011) 2611); the obtained corresponding transition pressure from fcc to hcp is also larger than that of CoVSb. For these distinctions, their complete different electronic and magnetic behaviors in their cubic structures may be responsible. However, in their hexagonal structures, atomic configurations are similar in terms of the analysis of both the ground-state structure and enthalpy-pressure curves. It is also shown that the elastic instability of cubic FeVSb does not appear with pressure upto 120 GPa and should not be a reason for the pressure-induced phase transition. In addition, heat capacity, Debye temperatures, and so on are obtained successfully for cubic FeVSb under the quasi-harmonic Debye model. Furthermore, we attempt to explore the phase diagram of FeVSb with the model. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
FeVSb;Mechanical properties;Thermodynamics properties;Phase;transition;Generalized gradient approximation;semi-heusler compounds;ab-initio calculations;electronic-structure;elastic-constants;thermoelectric-materials;transport-properties;crystals;pressure;gap;instabilities
