Fuxing YIN
,
Y. Ohsawa and A.Sato (National Research Institute for Metals
,
Tsukuba
,
Ibaraki 305-0047
,
Japan)K.Aawahara(B.B.Materia Co. Ltd.
,
Chiba-Shi
,
Chiba 267-0066
,
Japan)
材料科学技术（英文）
A high damping condition is easily obtained in Mn-(16~24)Cu-(4~6)Ni-2Fe (at. pct) alloys,when cooling rate is controlled after the solid solution treatment at 1173 K. It is observed that the temperature dependent changes of Iogarithmic decrement in 10 h cooled samples are sensitive to the alloy composition. As compared with water quenching treatment, controlled 10 h cooling improves TN temperature of the alloys extensively by producing a Mn-enriched matrix portion in the alloys. Calcuiations suggest that the relative decreases of Cu and Ni content in the matrix portion be dominated by the Ni content in the original alloys, and therefore, the volume fraction of the Cu, Ni-enriched precipitates is estimated to be about 20% and 10% in the 4Ni and 6Ni alloys, respectively. As a result, the TN temperature fOr each alloy, corresponding to the rising temperature of logarithmic decrement, has been related to the Cu, and Ni content in the Mnenriched matrix. The existence of {110} twinning boundaries is confirmed in the microstructure of both 4Ni and 6Ni alloys. However, the relative lattice strains, which the twinning boundaries act to accommodate, are found largely different in the two alloys. It is considered that boundaries with smaller orientation deviation could coordinate the external Stresses easily by cyclic moving, and therefore, the broader damping peak which occurs in the 10 h cooled 6Ni alloy becomes feasible. Electron diffraction results also indicate possible for mation of many sub-crystals in the matrix phase, which are relatively rotated on some invariant planes. Those sub-crystal boundaries might play some attenuation roles in the temperature range between TN and room temperature.
关键词:
WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
,
Lawrence Livermore National Laboratory
,
Livermore
,
CA 94551)
金属学报(英文版)
The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.
关键词:
: U.S. Materials Science. U.S. National Laboratories and Facilities
,
null
Yan NIU
,
Weitao WU and Chaoliu ZENG (State Key Lab. for Corrosion and Protection
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)F. Gesmundo and F. Viani (Instituto di Chimica
,
Facolta di Ingegneria
,
Un
材料科学技术（英文）
The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe
关键词:
材料科学技术（英文）
The corrosion of an Fe-based alloy containing 15 wt pet Y in H-2-H2S mixtures under 10(-3) Pa S-2 was studied at 600 similar to 800 degrees C in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneficial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus, Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition, but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12 similar to 17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe.
关键词:
high-temperature sulfidation;most-reactive component;ni-nb alloys;h2-h2s mixtures;behavior;600-degrees-c-800-degrees-c;oxidation
S.H.O
材料科学技术（英文）
The magnetic property of soft magnetic metals and alloys depends strongly on the crystallographic orientation. In automated equipment for orientation research. the intensity for drawing up the pole figure is measured in detail. The present research shows that the accurate pole figure can be drawn up without measuring concretely the intensity. For directional Si steel sheet the measuring step may be 4 similar to 5 degrees. In this paper the experimental equation for defocusing correction was derived from the experimental data in different specimens with random orientation.
关键词:
Philosophical Magazine a-Physics of Condensed Matter Structure Defects and Mechanical Properties
A first-principles method based on the local-density approximation using discrete variational clusters has been used to study the electronic structure of the hcp metals, Be, Mg, Sc, Y, Ti, Zr, Co, Zn and Cd. The binding energy of these metals was calculated in relation to the volume of a unit cell. The variation in the binding energy with the unit cell volume was obtained by means of a polynomial fit. The theoretical tensile strength and bulk modulus of these metals were estimated from the electronic structure and binding energy calculations. The predicted bulk moduli for these metals are in good agreement with experimental findings and other available theoretical data. A linear relationship between the calculated and the experimental strengths is observed.
关键词:
potentials;density
X.L. Tian C.W. Zhan J.X. Hou X.C. Chen J.J. Sun
材料科学技术（英文）
A nanocrystal model for liquid metals and amorphous metals has been developed. With the nanocrystal model, the broadening peak profiles (BPPs) of Cu, Al, Al65Cu20Fe15 alloy, Cu70Ni30 alloy and Fe50Si50 alloy were gained by broadening the X-ray diffraction (XRD) peaks of a crystal lattice. By comparing the BPPs with the XRD intensity curves measured on the liquid metals, it is found that the BPPs are closely in agreement with the XRD intensity curves, respectively, except the Fe50Si50 alloy. Therefore, the nanocrystal model can be used to determine if the atomic cluster structure of the liquid metal is similar to the structure of its crystal lattice.
关键词:
Liquid metal
,
Atomic Cluster
,
Structure
,
Crystal Lattice
