材料期刊网

HIGH STRAIN RATE SUPERPLASTICITY OF DISCONTINUOUS CERAMIC FIBER REINFORCED ALUMINUM COMPOSITES

T. Imai , L. Geng , J. F. Mao and I. Tochigi 1) National Industrial Research Institute of Nagoya , 1-1 Hirate-cho , Kita-ku , Nagoya , 462-8510 , Japan 2) School of Materials Science & Engineering , Harbin Institute of Technology , Harbin 15001 , China 3) Kanagawa High-Technology Foundation , Kanagawa Science Park , 3-2-1 , Sakado , Takatsu-ku , Kawasaki , Kanagawa 213 , Japan

金属学报(英文版)

β-Si3N4 whisker reinforced aluminum composites was fabricated by squeeze casting before extrusion and an effect of content of Mg on the High Strain Rate Superplastic- ity (HSRS) were investigated, The optimum temperature of the composites at which maximum total elongation is obtained decreases according to magnesium content and the β-Si_3N_4w/Al-3Mg exhibits the total elongation of about 200% at the strain rate of 10~(-1) s~(-1) and at 853-858 K, although the β-Si_3N_4w/Al-0Mg composite shows about 100% elongation at the strain rate of about 1×10~(-1) s~(-1) at 903-913 K. Optimum strain rate of the composites fabricated by squeeze casting was about 1×10~(-1) s~(-1) but TEM observation indicates that the β-Si_3N_4w/Al-Mg has a fine grain of about 2- 3μm and that the whisker might no react with Mg at the interfaces, although the β-Si_3N_4 whisker react with aluminum matrix.

关键词: high strain rate superplasticity , null , null

EVALUATION OF EMBRITTLEMENT BEHAVIOR DUE TO SENSITIZATION IN A CRYOGENIC AUSTENITIC STAINLESS STEEL BY MEANS OF SMALL PUNCH AND FRACTURE TOUGHNESS TESTS

S.C Liu(Research Institute for Fracture Technology Faculty of Engineering , Tohoku University , Sendai , Japan , on leave from Dalian Railway Institute , Dalian 116028 , China)II-Hyun Kown , T Hashida and H Takahashi(Research Institute for nacture Technology , Faculty of Engineering , Tohoku Univeristy , Sendai , Japan)

金属学报(英文版)

In order to evaluate the tendency of mechanical properties degrudation due to weld-ing and other processing in materials used for supporting coils in super conducting rnaguets utilized in thermonuclear jusion reactore, a small punch (SP) test was used.This test, which was originally developed to study irradiation damage using miniatursized specimens was performed at 77 and 4 K for solution treated and sensitized JN1 austenitic stainless steel, a candidate cryogenic structural material. The area under the load-deflection curve up to the maximum applied load in SP test was defined as the SP enerpy, to characterize the resistance to fracture. Although solution treated material exhibited ductile fracture mode with high SP enerpy, embrittlement behavior due to sensitization at 650-800°for 1-5 h was shown clearlg by SP test with brittle intergranular fracture and decreased SP enerpy. Comparison of the results obtained by SP test with those by fracture toughness test showed the usefulness of SP test for evaluation of sensitization induced embrittlement at cryogenic temperature. The re-sults obtained in this study can be very usefol in predicting the degradation due to welding and other processing in cryogenic materials.

关键词: small punch test , null , null , null

ELEVATED AND ROOM TEMPERATURE MECHANICAL BEHAVIOR OF BORON DOPED NiAl ALLOYS

TAN YiDalian University of Technology , Dalian , ChinaSHINODA THitachi Research Laboratory , Hitachi Ltd. 391-12 Hitachi , JapanMISHIMA YTokyo Institute of Technology , Nagatuta. Midori-Ku , Yokohama 227 , JapanSUZUKI TDepartment of Metallurgical Engineering , Tokyo Institute of Technology. Ookayama , Meguro-Ku , Tokyo 152 , Japan

金属学报(英文版)

The effects of boron addition on defect hardening at room temperature and on high temperature creep properties are investigated in the B2 NiAl intermetallic compound. It is found that boron addition is effective on increasing the room temperature hardeness on the Ni-rich side but it has no effect on the A1-rich side of stoichiometry. These observations are attributed to interstitial dissolution of boron in Ni-rich NiAl and to a lack of solubility and also due to an enrichment at grain boundaries on the A1-rich side. The similar effect is found in high temperature creep resistance of NiAl by boron addition. The high temperature creep resistance increases on the Ni-rich side but it does not affect the A1-rich side of off-stoiciometry.

关键词:

R & D OF HYDROGEN ABSORBING ALLOYS IN JAPAN

K. Mii (Sumitomo Metal Industries , Ltd. , 1-t-3 Otemachi , Tokyo 100 , Japan)M Amano (National Research Institute for Metals , 1-2-1 Sengen , Tsukuba 305 , Japan)

金属学报(英文版)

The R & D of hydrogen absorbing alloys in Japan started in the early 1970s.Many alloys such as TiMm1.5 based alloys, Fe-Ti-O alloys (e.g. FeTi1.15 O0.024) andthe(mischmetal)Ni5 based alloys (e.g. MmNi4.5 Cr0.46 Mn0.04) were developed by the early 1980s. The application of these alloys to hydrogen storage, heat storage, heat pump, hydrogen purification and motor vehicles has been tried in many iaboratories,and the various techniques for using hydrogen absorbing alloys have been developed.The standarkization of evaluation methods for hydrogen absorbing alloys has been promoted by the Ministry of International Trade and Industry (MITI), and four of them were established as Japanese Industrial Standard (JIS).Alloys for Ni-Metal Hydride batteries have been extensively investigated since 1987in Japun. Mm-Ni-Co-Al-Mn alloys (e.g. MmNi3.55 Co0.75Al0.9Mn0.4) have been devel-oped and commereialized since 1990. The amount of production of small-size Ni-MH batteries in 1995 was about three hundred milliion in number and about one hundred billion yen. The R & D for higher enerpy-density Ni-MH batteries is intensively in progress.MITI and STA (Science and Technology Agency) have promoted the R & D of hydro-gen absorbing alloys in Japan by carrying out the national projects such as Sunshine Program (MITI: 1974-1993) and Utilization of Wind Engeray (STA 1980-1985). The New Sunshine Program (MITI 1993-2020) have started in 1993. This program con-tains the application of hydrogen absorbing alloys to Economical- Enerpy- City System and to We-NET (International Clean Energy System of Technology Utilizing Hydro-gen: World Energy Network.

关键词: hydrogen absorbing alloy , null , null , null

INTERMETALLIC COMPOUNDS AND THEIR FORMATION REACTIONS IN SYSTEM Fe-Cr-Mo AT HIGH-TEMPERATURES

LIU Shicheng , Dalian Railway Insitute , Dalian , ChinaHamaguchi Yoshikazu , Kuwano Hisashi , Muroran Institute of Technology , Muroran , Japan

金属学报(英文版)

The stable ranges concerning the composition and temperature have been experimentally de- termined for the intermetallic compounds in system Fe-Cr-Mo at high-temperatures. The isothermal section of the Fe-Cr-Mo ternary phase diagram at 1250℃ and the formation re- actions for the intermetallic compounds, which are different in part from those shown in the literature, have been proposed.

关键词: Fe-Cr-Mo system , null , null , null , null

CHARACTERISTICS OF METAL-HYDROGEN INTERACTION IN HYDROGEN STORAGE ALLOYS

M.Morinaga and H. Yukawa Department of Materials Science and Engineering , Graduate School of Engineering , Nagoya University , Furo-cho , Chikusa-ku , Nagoya 464-8603 , Japan

金属学报(英文版)

The electronic structures are calculated by the DV-Xa molecular orbital method employing small model clusters in order to clarify the roles of the hydride forming elements, A, (e.g., La, Zr Ti, Mg) and non-forming elements, B, (e.g., Ni, Mn, Fe) in hydrogen storage alloys. It is confirmed from this calculation that hydrogen interacts more strongly with hydride non-forming elements, B, than hydride forming elements, A, in agreement with our previous calculations. However,the B-H interaction is enhanced only when some A element exists in the neighborhood. Otherwise, such a B-H interaction never operates in the alloy. In this sense,the coexistence of A and B elements are essential in the constitution of hydrogen storage alloys. Also, it is shown that the A/B compositional ratio of hydrogen storage alloys is understood in terms of a simple parameter, 2Bo(A - B) / /Bo(A - A)+ Bo(B-B)], where the Bo(A-B), Bo(A-A) and the Bo(B-B) are the bond strengths between atoms given in the parentheses.

关键词: electronic structure , null , null , null , null , null , null

Foreword for the special issue of the 7th China-Japan bilateral symposium on high temperature strength of materials

金属学报(英文版)

关键词:

Recent Developments in the Continuous Processing of Steels

Hiroshi Takechi Nippon Steel Corporation , Japan.

材料科学技术（英文）

This paper reviews recent developments in the contin- uous processing of steels in Japan.The following items are discussed:continuous casting-direct rolling(CC-DR) process of hot-rolled strip:thermomechanical control process(TMCP)of heavy plates:in—line heat treating pro- cess of rails:direct lead patenting(DLP)process of wire rods;and fully integrated processing line(FIPL)of cold-rolled strip.

关键词: continuous casting , null , null , null

热空气老化和热水老化对PC冲击性能的影响

詹茂盛 , 方义 , 王瑛 , 范荣峥

航空材料学报 doi:10.3969/j.issn.1005-5053.2000.04.010

在40℃和80℃环境中,分别对Bayer-PC、Japan-PC、Korea-PC三种聚碳酸酯缺口冲击试样进行了热空气老化和热水老化实验研究.在0～400h老化时间内,研究了这三种PC的热空气老化和热水老化对冲击强度和断面形貌的影响,讨论了PC热空气老化和热水老化机理.结果表明:老化前,Japan-PC、Korea-PC和Bayer-PC冲击强度分别为95kJ/m2、83 kJ/m2和55 kJ/m2;在40℃和80℃热空气老化后,三种PC冲击强度均有所下降,其中80℃热空气老化引起的降幅最大,热空气老化400h后的冲击强度顺序为Japan-PC>Korea-PC>Bayer-PC,在40℃热水老化后,三种PC的冲击强度几乎不受老化时间影响;在80℃热水老化后,三种PC冲击强度均有所下降,其中Bayer-PC降幅最小,Japan-PC次之,Korea-PC最大,但PC的平衡冲击强度大小与热空气老化的情况相同.由扫描电镜对冲击断面形貌观察可知,未老化的三种PC均以剪切屈服破坏机理为主,老化后的三种PC主要以银纹集中破坏机理为主.

关键词: 聚碳酸酯 , 热空气老化 , 热水老化 , 破坏形貌

DEVELOPMENT OF THE RISK-BASED MAINTENANCE OPTIMIZATION SYSTEM FOR FOSSIL POWER PLANTS

D.Watanabe

金属学报(英文版)

Cost reduction in electric power generation is a major management concern, and it is therefore necessary to reduce maintenance expenses while upholding plant reliability. A maintenance optimization system "FREEDOM", which uses RBM technique, DCF (discounted cash flow) and NPV (net present value) calculation functions, has been newly developed. This system probabilistically evaluates the lifetime of boiler and turbine and quantitatively calculates the risk defined as the cumulative probability of failure multiplied by the consequence of failure. Economically optimized timing of inspection and alternative countermeasure such as repair and replacement are then recommended. This system has already been applied to seven plants in Japan, and its effectiveness has been confirmed.

关键词: plant asset management , null , null