LI Geping
,
GUAN Shaoxuan
,
WANG Qingjiang
,
LIU Yuyin
,
LI Dong
,
HU Zhuangqi (Institute of Metal Researeh
,
Chinese Academy of Sciences
,
Shenyang
,
China Manuscript received 23 January. 1995)
金属学报(英文版)
The morphologies of the Nd-rich phase particles in the Ti-5Al-4Sn-2Zn -1Mo-0.25Si-1Nd alloy after high temperature deformation are investigaied by optical microscope and transmission electron microscope. It is found that the Nd-rich phase particles are 1.0～14 μm in diameter and uniformly distributed in ihe matrix, and the majority of the particles are elliptical. Under high temperature deformaiton, high stress concentration occurs on the particles, the particles near to sphericity are obtained.
关键词:
: Ti alloy
,
null
,
null
王君
,
邹家桂
,
陈政标
,
高建武
,
刘彦坤
,
张杰元
,
宋莎
绝缘材料
为解决苯乙烯和甲基苯乙烯在VPI浸渍树脂应用于风力发电机中的不足，采用不饱和聚酯亚胺、引发剂和无挥发活性稀释剂研制出116HU聚酯亚胺无挥发浸渍树脂，并对其各项性能进行了研究。结果表明：116HU聚酯亚胺无挥发浸渍树脂的常规性能满足风力发电机的要求，其耐热等级可达H级。用该树脂浸渍的风电模拟线棒具有优异的介电性能、耐湿热交变和高低温循环冲击性能及耐盐雾性能等，能满足风力发电机在极端环境运行的要求。
关键词:
聚酯亚胺
,
无挥发
,
VPI
,
风力发电机
,
耐湿热
,
耐盐雾
MA Zongyi YAO Zhongkai Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure
关键词:
composite
,
null
,
null
,
null
Applied Physics Letters
The dielectric resonance and multiple magnetic resonances which correspond to multiple microwave absorptions in the 2-18 GHz range have been studied in the composite Fe/TiO(2). The Fe grain size is found to have great impact on the dielectric resonance in this metal-semiconductor composite. The polarization mechanism is attributed to interfacial polarization. The multiple magnetic resonances can be ascribed to the natural resonance and exchange resonances, which can be explained by Aharoni's exchange resonance theory. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3496393]
关键词:
ferromagnetic particles;carbon nanotubes;absorption;permeability
材料科学技术（英文）
Molecular structures of adsorbed waters at metal surfaces are essential to understanding the widespread processes ranging from ice nucleation, to water involved catalytic surface reactions, to many phenomena of biological and astrochemical importance. Instead of providing a comprehensive literature survey, we focus in this review on detailed structural information, such as water orientations and occupation sites, of intact waters at low temperatures and ultrahigh vacuum conditions investigated by various surface techniques. Despite progresses made in direct imaging the surface waters at high resolutions, as exemplified in a close-packed (e.g. Pd(111)) and an open metal surfaces (e.g. Cu(110)) supported waters, structural mysteries remain at diverse metal surfaces. We highlight experimental challenges and discuss structural mysteries in elucidating surface water structures at molecular levels.
关键词:
Water monolayer;Surface structure;Transition metal surfaces;scanning-tunneling-microscopy;density-functional theory;vibrational-spectra;ice;pt(111);adsorption;dissociation;ru(0001);excitation;molecules
Jibiao Li Shenglong Zhu Fuhui Wang
材料科学技术（英文）
Molecular structures of adsorbed waters at metal surfaces are essential to understanding the widespread processes ranging from ice nucleation, to water involved catalytic surface reactions, to many phenomena of biological and astrochemical importance. Instead of providing a comprehensive literature survey, we focus in this review on detailed structural information, such as water orientations and occupation sites, of intact waters at low temperatures and ultrahigh vacuum conditions investigated by various surface techniques. Despite progresses made in direct imaging the surface waters at high resolutions, as exemplified in a close-packed (e.g. Pd(111)) and an open metal surfaces (e.g. Cu(110)) supported waters, structural mysteries remain at diverse metal surfaces. We highlight experimental challenges and discuss structural mysteries in elucidating surface
water structures at molecular levels.
关键词:
Water monolayer
,
surface structure
,
transition metal surfaces
J.Q.ZHANGD.J.YOUNG
中国腐蚀与防护学报
Metaldusting attacks iron, low and high alloy steels and nickel-or cobalt-base alloys by disintegrating bulk metals and alloys into metal particles in a coke deposit. It occurs in strongly carburising gas atmospheres (carbon activity aC>1) at elevated temperatures (400 ℃~1000 ℃). This phenomenon has been studied for decades, but the detailed mechanism is still not well understood. Current methods of protection against metal dusting are either directed to the process conditions-temperature and gas composition-or to the development of a dense adherent oxide layer on the surface of the alloy by selective oxidation. However, metal dusting still occurs by carbon dissolving in the base metal via defects in the oxide scale. The research work at UNSW is aimed at determining the detailed mechanism of metal dusting of both ferritic and austenitic alloys, in particular the microprocesses of graphite deposition, nanoparticle formation and underlying metal destruction. This work was carried out using surface observation, cross-section analysis by focused ion beam and electron microscopic examination of coke deposits at different stages of the reaction. It was found that surface orientation affected carbon deposition and metal dusting at the initial stage of the reaction. Metal dusting occurred only when graphite grew into the metal interior where the volume expansion is responsible for metal disintegration and dusting. It was also found that the metal dusting process could be significantly changed by alterations in alloy chemistry. Germanium was found to affect the iron dusting process by destabilising Fe3C but increasing the rate of carbon deposition and dusting, which questions the role of cementite in ferritic alloy dusting. Whilst adding copper to iron did not change the carburisation kinetics, cementite formation and coke morphology, copper alloying reduced nickel and nickel-base alloy dusting rates significantly. Application of these fundamental results to the dusting behaviour of engineering alloys is discussed.
关键词:
metal dusting
,
null
,
null
,
null
,
null
,
null
Journal of Applied Physics
To date, high compressive ductility and energy absorption have been achieved in amorphous metal foams based on high-toughness Pd- and Zr-based metallic glasses and are known to result from two extrinsic toughening mechanisms: bending of struts and shear band arrest by pores. We study here a syntactic amorphous metallic foam produced by infiltration of a bed of hollow crystalline iron spheres with a low-toughness Mg-based metallic glass (Mg60Cu21Ag7Gd12). After quenching to vitrify the matrix, this foam exhibits much higher compressive failure strain and energy absorption than the monolithic metallic glass, an improvement which is assigned to an intrinsic mechanism, i.e., composite toughening by the network of hollow ductile iron spheres.(C) 2007 American Institute of Physics.
关键词:
glass matrix composites;mechanical-properties;enhanced plasticity;syntactic foams;alloys;fabrication;damage
Applied Physics Letters
The magnetotransport behaviors of a series of rare earth manganites with the same A-site cational mean radius and different A-site ionic radii variance (A-site disorder) are investigated. It is found that the system's ground state transforms from ferromagnetic metal to cluster-glass insulator with increasing A-site disorder. In the cluster-glass state, the magnetization shows the steplike behavior, indicating the existence of short-range magnetically ordered clusters. The significant effect of the A-site disorder on the electronic phase separation is revealed by detecting the cluster-glass ground state at low temperature. (c) 2006 American Institute of Physics.
关键词:
manganese oxide perovskites;phase-separation;cation disorder;double-exchange;magnetoresistance;resistivity
