QI Yunxin TANG Wentai XIA Jianguo Nei Mongol Institute of Metallic Materials
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Baotou
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ChinaLI Wang ZHAN Zhenzong Institute of Physical and Chemical Engineering Research
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Tianjin
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China
金属学报(英文版)
The surface segregation of substrate elements through the Au layer in the Au-Ni-Kovar sys- tem specimens heated at 250—350℃ for 0.5—1.5 h has been studied by SAM and XPS. Visual evidence of the mechanism for Ni and Co surface segregation of the complicated sys- tem has been given,i.e.Ni and Co penetrated the gold layer mainly by grain boundary diffu- sion and then covered the Au layer by surface diffusion.The strdy results of the chemical states of surface segregation elements not only indicate that oxygen adsorption and oxidation reaction are the driving force for the surface segregation of Ni and Co,but also show that the above segregation can result in water absorption on surfaces.
关键词:
Au-Ni-Kovar alloy system
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Journal of the Physical Society of Japan
In this study, we implement first-principles calculation to study the physical and chemical properties of two-dimensional (2D) hexagonal crystals. The ab initio results of the crystallographic, elastic, and electronic band-gap parameters of C, Si, Ge, BN, CN, SiN, and SiC monolayers are presented. Similarly to graphene, CN and BN are among compounds with the highest 2D elasticity. The in-plane elastic moduli of Si and Ge monolayers are relative small. C, Si, and Ge monolayers are semimetal. All the four binary 2D crystals are semiconductors with wide band gaps. Two typical 2D hexagonal lattice structures, i.e., sp(2) flat and sp(3) rumpled configurations, are classified. The orbital sp(2)-hybridization in graphene and 2D BN is verified by angular-momentum projected atomic density of state calculation. 2D SiC is basically in sp(2)-hybridization. The orbital hybridization of Si, Ge, CN, and SiN monolayers is of the sp(3)-type on the whole. In view of the structural and chemical features of these monolayers, different methods for the experimental preparation of 2D crystals are suggested.
关键词:
2D crystals;orbital hybridization;elastic moduli;first-principles;calculation;iii-v compounds;elastic-constants;silicon-nitride;graphene;pseudopotentials;membranes;graphite;phase
Y.Chen X.Chen A.M.Guo D.X.Luo
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B.F.Xu
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Z.X.Yuan
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P.H.Li
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S.K.Pu
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S.B.Zhou
金属学报(英文版)
The different chemical composition of silicon and manganese as well as different re-tained austenite fraction ranged from 4to 101163326174f the high strength and high elon-gation steels were studied in the paper.The dislocations and carbon concentration in retained austenite were observed by a transmission electron microscope and an electric probe analyzer,respectively.The experimental results showed that silicon and manganese are two fundamental alloying elements to stabilize austenite effectively but retaining austenite in different mechanis-↑ms.Meanwhile,the cooling processing played an important role in controlling the fraction of retained austenite of the hot-rolled high strength and high plasticity steels.
关键词:
high strength
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Andrej Atrens
材料科学技术（英）
Corrosion research by Atrens and co-workers has made significant contributions to the understanding of the service performance of engineering materials. This includes: (1) elucidated corrosion mechanisms of Mg alloys, stainless steels and Cu alloys, (2) developed an improved understanding of passivity in stainless steels and binary alloys such as Fe-Cr, Ni-Cr, Co-Cr, Fe-Ti, and Fe-Si, (3) developed an improved understanding of the melt spinning of Cu alloys, and (4) elucidated mechanisms of environment assisted fracture (EAF) of steels and Zr alloys. This paper summarises contributions in the following: (1) intergranular stress corrosion cracking of pipeline steels, (2) atmospheric corrosion and patination of Cu, (3) corrosion of Mg alloys, and (4) transgranular stress corrosion cracking of rock bolts.
关键词:
Stress corrosion cracking
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Advanced Materials
Modern methods of in situ transmission electron microscopy (TEM) allow one to not only manipulate with a nanoscale object at the nanometer-range precision but also to get deep insights into its physical and chemical statuses. Dedicated TEM holders combining the capabilities of a conventional high-resolution TEM instrument and atomic force -, and/or scanning tunneling microscopy probes become the powerful tools in nanomaterials analysis. This progress report highlights the past, present and future of these exciting methods based on the extensive authors endeavors over the last five years. The objects of interest are diverse. They include carbon, boron nitride and other inorganic one- and two-dimensional nanoscale materials, e.g., nanotubes, nanowires and nanosheets. The key point of all experiments discussed is that the mechanical and electrical transport data are acquired on an individual nanostructure level under ultimately high spatial, temporal and energy resolution achievable in TEM, and thus can directly be linked to morphological, structural and chemical peculiarities of a given nanomaterial.
关键词:
transmission electron microscopy;nanotubes;nanowires;nanosheets;boron-nitride nanotubes;in-situ tem;filled carbon nanotubes;gan-nanowires;tensile tests;deformation;nanosheets;transport;graphene;nanocontacts
