Jiefeng Wu

Effects of Zr Addition on Strengthening Mechanisms of Al-Alloyed High-Cr ODS Steels

Oxide dispersion strengthened (ODS) steels with different contents of zirconium (denoted as 16Cr ODS, 16Cr-0.3Zr ODS and 16Cr-0.6Zr ODS) were fabricated to investigate the effects of Zr on strengthening mechanism of Al-alloyed 16Cr ODS steel. Electron backscatter diffraction (EBSD) results show that the mean grain size of ODS steels could be decreased by Zr addition. Transmission electron microscope (TEM) results indicate that Zr addition could increase the number density but decrease the mean diameter and inter-particle spacing of oxide particles. Furthermore, it is also found that in addition to Y-Al-O nanoparticles, Y-Zr-O oxides with finer size were observed in 16Cr-0.3Zr ODS and 16Cr-0.6Zr ODS steels. These changes in microstructure significantly increase the yield strength (YS) and ultimate tensile strength (UTS) of ODS steels through mechanisms of grain boundary strengthening and dispersion strengthening.

Plasma facing conponents of EAST

EAST plasma facing components (PFCs) have the function of protecting the vacuum vessel, heating systems and diagnostic components from the plasma particles and heat loads, and also additional to this particles and heat loads handling. They are installed in the vacuum vessel together with in-vessel coils, cryopump and diagnostic components. The design, fabrication and assembly have been finished. The PFCs are designed up-down symmetry to accommodate with both double null and single null plasma configuration. All PFCs use graphite tile for plasma facing surfaces affixed to copper alloy heat sink. A special deep hole drilling technology was developed to drill cooling channels directly on heat sink for high efficient heat removal. All Heat sink are installed onto the base alignment rails through stainless steel supports. As the benchmark of assembly for PFCs, the base rails are installed and measured precise based on a new alignment method integrating the optical instruments and a mechanical template. And so is a mechanical check template for checking the surface of first wall. As indicated, all the first wall components were fabricated and assembled successfully and meet the design requirement for the plasma operation.

The fabrication and preassembly of HT-7 Superconducting Tokamak

The HT-7 Superconducting Tokamak is being built in Hefei, China. It is a device reconstructed and upgraded from T-7 Tokamak of Russia. This project is a co-operating item of fusion research between Russia and China. The Research and Manufacturing Center (RMC), ASIPP is responsible for the fabrication and assembly of HT-7. The design of HT-7 was carried out by both of Russian and Chinese engineers in 1991, and the main parts of the machine were fabricated in 1992. The preassembly of HT-7 was completed in April, 1993. This paper emphasizes on the manufacturing steps necessary to produce the HT-7 and a series of technological methods to overcome the key techniques.

Statistical Mechanics Treatment of the Broadened Snoek Relaxation Peak in Ternary Niobium–Vanadium–Oxygen Alloys

The Snoek relaxation profiles for ternary Niobium–Vanadium–Oxygen systems were analyzed by an embedded-cell model of statistical mechanics treatment. The relaxation characteristic and broadening mechanism were systematically discussed and some conflicting interpretations in the early research were clarified. The complicated Snoek spectrums of the Nb–V–O system can be resolved into a series of effective elementary Debye peaks, which result from the transitions of interstitial oxygen atoms between adjacent octahedral sites. The relaxation parameters of each elementary peak can be determined by element species and atomic arrangements within the corresponding embedded octahedron. The Snoek relaxation characteristic in Nb–V–O systems mainly depends on the sites distributions and the transitions status of the interstitial oxygen atoms, which are controlled by the site-dependence energies and the transition probabilities, respectively.