{"currentpage":1,"firstResult":0,"maxresult":10,"pagecode":5,"pageindex":{"endPagecode":5,"startPagecode":1},"records":[{"abstractinfo":"Polycrystalline Fe78B13Si9 alloys with nanoscale grain sizes prepared by the crystallization method have been studied by positron <span style=\"color:red\">lifetime</span> and Doppler-broadened line-shape measurements. The results obtained are different from those on amorphous or coarse-grained crystalline alloys with the same composition. When the grain sizes are clearly smaller than the mean positron diffusion length (L+ congruent-to 100 nm), saturation trapping and annihilation of the positrons in the samples should occur at traps within the interfaces. There are two kinds of defects in the interfaces of the nanocrystalline FeBSi alloys, i.e., the free volumes (the size of which is slightly smaller than that of the amorphous counterpart) and the microvoids. The dependence of grain sizes on the type of interface defects and strucure-sensitive properties has also been studied by positron <span style=\"color:red\">spectroscopy</span>. The measurements and comparison of the mean positron <span style=\"color:red\">lifetime</span> tauBAR and the Doppler pammeter S on the nanocrystalline amorphous, and coarse-grained crystalline alloys have given a satisfactory explanation for the relationship between the structure-sensitive properties, grain sizes, and crystalline states.","authors":[],"categoryName":"|","doi":"","fpage":"5124","id":"8b38c813-11d5-449e-b533-5345be0dc28f","issue":"11","journal":{"abbrevTitle":"JOAP","id":"7dcf8a89-0513-40ee-be2d-759941dcef7e","issnPpub":"0021-8979","publisherId":"JOAP","title":"Journal of Applied Physics"},"keywords":[{"id":"b4c96398-a5dd-445e-ae84-14e15db4eb41","keyword":"<span style=\"color:red\">lifetime</span> <span style=\"color:red\">spectroscopy</span>;<span style=\"color:red\">metals</span>;<span style=\"color:red\">vacancies</span>;<span style=\"color:red\">iron</span>","originalKeyword":"lifetime spectroscopy;metals;vacancies;iron"}],"language":"en","publisherId":"0021-8979_1992_11_1","title":"INVESTIGATIONS ON NANOCRYSTALLINE FE78B13SI9 ALLOYS BY POSITRON-ANNIHILATION <span style=\"color:red\">SPECTROSCOPY</span>","volume":"72","year":"1992"},{"abstractinfo":"The mechanism of melting is investigated by considering the role of surfaces with regard to the concentration and migration of <span style=\"color:red\">vacancies</span>. For many <span style=\"color:red\">metals</span>, it is found that while the vacancy concentration in the bulk is similar to 0.37% at the equilibrium melting point (T-0), the vacancy concentration at the free surface is as high as 10%, i.e. similar to that in the bulk at the superheating limit. Melting is believed to be associated with a lattice instability induced at a critical vacancy concentration of similar to 10%, both at the surface and within the crystal lattice. The abrupt increase in vacancy concentration from 0.37 to 10% on melting at T-0 can be explained as a result of melting of the surface. The surface pre-melting behaviour of <span style=\"color:red\">metals</span> is quantitatively interpreted by considering the vacancy migration there.","authors":[],"categoryName":"|","doi":"","fpage":"203","id":"3284e6d6-8689-465a-87d0-19c463286c34","issue":"3","journal":{"abbrevTitle":"PML","id":"b99457c8-ca12-41f0-ae76-446b65a3b4c0","issnPpub":"0950-0839","publisherId":"PML","title":"Philosophical Magazine Letters"},"keywords":[{"id":"d473b4d0-a7ab-4e13-9789-9671043e4f8e","keyword":"kinetic stability limit;crystals;au(110);al(110);point;al","originalKeyword":"kinetic stability limit;crystals;au(110);al(110);point;al"}],"language":"en","publisherId":"0950-0839_2008_3_1","title":"Melting of <span style=\"color:red\">metals</span>: role of concentration and migration of <span style=\"color:red\">vacancies</span> at surfaces","volume":"88","year":"2008"},{"abstractinfo":"Nanostructured Ag (polycrystalline Ag with nanometre-sized grains), synthesized by inert-gas condensation plus in situ vacuum compaction, has been investigated by positron <span style=\"color:red\">lifetime</span> <span style=\"color:red\">spectroscopy</span> (PLS). The results indicate that there is a common character, i.e. only three <span style=\"color:red\">lifetime</span> components (tau(1), tau(2) and tau(3)) are resolvable from the <span style=\"color:red\">lifetime</span> spectrum on each of the specimens synthesized under the whole compacting pressure range investigated (from 0.15 to 1.50 GPa). Corresponding to the three <span style=\"color:red\">lifetime</span> components, there are three types of defect (traps) in nanostructured Ag: (a) vacancy-like (VL) defects, (b) vacancy-cluster (VC) defects and (c) larger voids. Compacting pressure and annealing treatment has great influences on the positron annihilating behaviour. The lifetimes tau(1), tau(2) and corresponding intensities I-1, I-2 decreased irreversibly with compacting pressure and annealing temperature, indicating that the VL defects and VC defects are both mechanically and thermally unstable, and so it is inappropriate to consider them as structural elements in nanostructured Ag. Moreover, the interfaces in n-Ag can be considered as superpositions of VL defects on the normal ordered boundaries, and since the number and size of the VL defects change with external conditions, the interfaces in n-Ag can stay in various metastable states, which implies that its interfacial structures may range from total random states (gaslike) to complete ordered structures, depending on the number and size of the VL defects contained. The forming process of bulk nanostructured Ag revealed by PLS can be roughly divided into three stages: (1) formation stage of interfaces (compacting pressure p less than or equal to 0.6 GPa); (2) rapid elimination of the three types of defect (0.6 GPa < p < 1.1 GPa); (3) gradual elimination of those defects (p > 1.1 GPa). Based on these results obtained on nanostructured Ag, a density criterion D-c approximate to 96% that of the polycrystalline counterpart is proposed for the formation of bulk nanostructured materials.","authors":[],"categoryName":"|","doi":"","fpage":"3075","id":"dbd64d01-5257-4aef-972f-6d4de2fd6fd7","issue":"13","journal":{"abbrevTitle":"JOPM","id":"f0e359df-48a6-4a7f-b16d-2389d3e793ee","issnPpub":"0953-8984","publisherId":"JOPM","title":"Journal of Physics-Condensed Matter"},"keywords":[{"id":"83f1d051-04db-4470-9516-a4823178d436","keyword":"nanocrystalline materials;temperature-dependence;grain-boundaries;palladium;microstructure;diffusion;<span style=\"color:red\">metals</span>;hrem;<span style=\"color:red\">iron</span>","originalKeyword":"nanocrystalline materials;temperature-dependence;grain-boundaries;palladium;microstructure;diffusion;metals;hrem;iron"}],"language":"en","publisherId":"0953-8984_1998_13_1","title":"Formation process of interfaces and microdefects in nanostructured Ag studied by positron <span style=\"color:red\">lifetime</span> <span style=\"color:red\">spectroscopy</span>","volume":"10","year":"1998"},{"abstractinfo":"A nanocrystalline Ni-P alloy prepared by the crystallization method has been studied by using positron <span style=\"color:red\">lifetime</span> <span style=\"color:red\">spectroscopy</span>. The <span style=\"color:red\">lifetime</span> results and the corresponding interfacial defects in the sample are discussed in comparison with those of the nanocrystalline <span style=\"color:red\">iron</span> materials prepared by compacting ultrafine powders.","authors":[],"categoryName":"|","doi":"","fpage":"4451","id":"9bb26cb3-d5b5-4118-9d07-bcefab5b44c8","issue":"8","journal":{"abbrevTitle":"JOAP","id":"7dcf8a89-0513-40ee-be2d-759941dcef7e","issnPpub":"0021-8979","publisherId":"JOAP","title":"Journal of Applied Physics"},"keywords":[{"id":"a709fbdb-8c24-461f-a734-8b8d842355b0","keyword":"<span style=\"color:red\">lifetime</span> <span style=\"color:red\">spectroscopy</span>;<span style=\"color:red\">iron</span>","originalKeyword":"lifetime spectroscopy;iron"}],"language":"en","publisherId":"0021-8979_1991_8_2","title":"INVESTIGATION OF THE INTERFACIAL DEFECTS IN A NANOCRYSTALLINE NI-P ALLOY BY POSITRON-ANNIHILATION <span style=\"color:red\">SPECTROSCOPY</span>","volume":"69","year":"1991"},{"abstractinfo":"Effect of Si, Al and Bi on the microstructure and mechanical properties of as-welded and austempered ductile <span style=\"color:red\">iron</span> weld <span style=\"color:red\">metals</span> has been studied with SEM, TEM, X-ray diffraction, image analysing system, tension and other test methods. Results show that increasing weld Si, Al and Bi content favours improving the chilling tendency of as-welded ductile <span style=\"color:red\">iron</span> weld and mechanical properties of austempered ductile <span style=\"color:red\">iron</span> weld and the mechanism is also discussed. On this basis the optimum chemical composition of weld is determined. The mechanical properties of weld and welded joint after austempering can match those of austempered ductile <span style=\"color:red\">iron</span>","authors":[{"authorName":"Daqian SUN","id":"1e08e77a-ae86-4033-b4f4-ee620212ae42","originalAuthorName":"Daqian SUN"},{"authorName":" Zhenfeng ZHOU and Haicheng CAO (Dept. of Mater. Sci. Eng.","id":"79e7cd8e-45a1-4c0e-8618-2575b558f1c1","originalAuthorName":" Zhenfeng ZHOU and Haicheng CAO (Dept. of Mater. Sci. Eng."},{"authorName":" Jilin University of Technology","id":"da9859fb-f6bb-48e0-9720-d6b75b93b33e","originalAuthorName":" Jilin University of Technology"},{"authorName":" Changchun 130022","id":"7edaac7a-3923-4cc2-8380-8ce85cedf67a","originalAuthorName":" Changchun 130022"},{"authorName":" China)","id":"2a2e5750-7fe4-4120-80cc-a1add9dc8e80","originalAuthorName":" China)"}],"categoryName":"|","doi":"","fpage":"347","id":"b19f4508-e0fe-4502-bb10-6c76ef8d2e70","issue":"5","journal":{"abbrevTitle":"CLKXJSY","coverImgSrc":"journal/img/cover/JMST.jpg","id":"11","issnPpub":"1005-0302 ","publisherId":"CLKXJSY","title":"材料科学技术（英文）"},"keywords":[],"language":"en","publisherId":"1005-0302_1996_5_2","title":"Effect of Si, Al and Bi on Structure and Properties of As-welded and Austempered Ductile <span style=\"color:red\">Iron</span> Weld <span style=\"color:red\">Metals</span> during Gas Welding","volume":"12","year":"1996"},{"abstractinfo":"The results of positron <span style=\"color:red\">lifetime</span> and Doppler broadening spectrum of defects in the hydrogen charged non-heat treatable 5xxx Al alloys are presented in this work. The yield stress of the sample was reduced for about 20 MPa after hydrogen was charged. A similar trend was observed in positron <span style=\"color:red\">lifetime</span> measurement, as the average <span style=\"color:red\">lifetime</span> tau(av) descended remarkably to almost the level of Al matrix. The change in coincidence Doppler broadening (CDB) <span style=\"color:red\">spectroscopy</span> was also significant, exhibited by the characteristic change in CDB radio curves of a sample before and after hydrogen was charged. After hydrogen charging, there is an obvious enhancement in the high momentum region compensating dehancement in the low momentum region. This indicates the existence of hydrogen filling effect. The <span style=\"color:red\">vacancies</span> around the Mg atoms should be preferential filling sites for hydrogen because Mg has a strong affinity for hydrogen. The formation of an Mg-H bond parallel to a grain boundary is an important factor in weakening the grain boundary cohesion.","authors":[],"categoryName":"|","doi":"","fpage":"1791","id":"c2221e8f-4a27-4ddd-9172-4c1cca689436","issue":"5","journal":{"abbrevTitle":"JOMR","id":"155c387a-c8cb-4083-85f3-6b58aeef4116","issnPpub":"0884-2914","publisherId":"JOMR","title":"Journal of Materials Research"},"keywords":[{"id":"2e2d155a-71b8-4603-9201-02a6f172aa69","keyword":"aa5754 alloys;annihilation","originalKeyword":"aa5754 alloys;annihilation"}],"language":"en","publisherId":"0884-2914_2009_5_3","title":"Positron <span style=\"color:red\">lifetime</span> and Doppler broadening study of defects in hydrogen charged Al-Mg alloys","volume":"24","year":"2009"},{"abstractinfo":"The protection behaviors of two new phosphate self-assembled films, triphenyl phosphate (TPP) and bis-(2-ethylhexyl) phosphate (BEP), against the corrosion of <span style=\"color:red\">iron</span> in 0.5 M H2SO4 were investigated using the electrochemical impedance <span style=\"color:red\">spectroscopy</span> (EIS), polarization curves, Fourier transform infrared (FT-IR) <span style=\"color:red\">spectroscopy</span>, and molecular simulations. The polarization curves showed a decrease in corrosion current density for the electrode covered with phosphates. Impedance spectra demonstrated that the charge-transfer resistance (R-ct) of the electrode covered with phosphate was greater than that of the naked <span style=\"color:red\">iron</span> electrode. Results show that TPP molecules can adsorb on the <span style=\"color:red\">iron</span> surface quickly in a short time and that the coverage (theta) of the film will get to the maximum in 4 h. Subsequently, the amount of TPP molecules on the <span style=\"color:red\">iron</span> surface remains constant, while theta of BEP on the <span style=\"color:red\">iron</span> surface increases with the immersion time in 24 h. FT-IR <span style=\"color:red\">spectroscopy</span> was applied for the surface analysis and confirmed the adsorption of phosphates on the <span style=\"color:red\">iron</span> surface by monitoring the functional group peaks of the compounds. Molecular simulations were performed to illustrate the adsorption process at a molecule level and to provide some theoretical information for our experiment.","authors":[],"categoryName":"|","doi":"","fpage":"3109","id":"6ce36b96-00b7-4bbf-9fdd-efb3394a6b96","issue":"7","journal":{"abbrevTitle":"JOPCC","id":"ac67555d-0402-4e5c-8a4c-93f73d479ea5","issnPpub":"1932-7447","publisherId":"JOPCC","title":"Journal of Physical Chemistry C"},"keywords":[{"id":"9cf3c1b9-c3d1-48be-a7a4-f694573afae5","keyword":"2-dimensional polymer-films;corrosion inhibition;alkanethiol;monolayers;copper corrosion;schiff-base;gold;protection;behavior;steel;acids","originalKeyword":"2-dimensional polymer-films;corrosion inhibition;alkanethiol;monolayers;copper corrosion;schiff-base;gold;protection;behavior;steel;acids"}],"language":"en","publisherId":"1932-7447_2007_7_1","title":"Investigations of triphenyl phosphate and bis-(2-ethylhexyl) phosphate self-assembled films on <span style=\"color:red\">iron</span> surface using electrochemical methods, Fourier transform infrared <span style=\"color:red\">spectroscopy</span>, and molecular simulations","volume":"111","year":"2007"},{"abstractinfo":"Polycrystalline Ni-P alloys with ultrafine grains from a few to one hundred nanometers in size prepared by the crystallization method have been studied by using positron-<span style=\"color:red\">lifetime</span> <span style=\"color:red\">spectroscopy</span>. Two kinds of microdefect were found in the interfaces of the Ni-P samples: free volumes (the size of which is smaller than a monovacancy) and microvoids. Variations on the interfacial defects with grain size were revealed by an analysis of the <span style=\"color:red\">lifetime</span> results. The interface characteristics derived from the positron-<span style=\"color:red\">lifetime</span> results can be used to give a satisfactory interpretation of the dependence of mechanical behaviors on the grain size. Differences between the interfacial defects of the nanocrystalline materials prepared by the ultrafine-powder compaction method and by the crystallization method were also discussed","authors":[],"categoryName":"|","doi":"","fpage":"6466","id":"dade0407-2c03-404a-a4d2-261ed7479a2d","issue":"12","journal":{"abbrevTitle":"PRB","id":"48ba155b-d6de-484c-bd85-973be949b8c5","issnPpub":"1098-0121","publisherId":"PRB","title":"Physical Review B"},"keywords":[{"id":"1e9f529f-c57e-4261-aa18-7e51b80cd180","keyword":"nanocrystalline materials;<span style=\"color:red\">spectroscopy</span>;<span style=\"color:red\">iron</span>","originalKeyword":"nanocrystalline materials;spectroscopy;iron"}],"language":"en","publisherId":"1098-0121_1991_12_1","title":"POSITRON-<span style=\"color:red\">LIFETIME</span> STUDY OF POLYCRYSTALLINE NI-P ALLOYS WITH ULTRAFINE GRAINS","volume":"44","year":"1991"},{"abstractinfo":"Precipitation in Inconel 625 alloy has been studied by positron annihilation <span style=\"color:red\">spectroscopy</span> and electron microscopy. The observed dependence of annihilation characteristics on aging time is attributed to the change of the positron state due to the increase and decrease of the density and size of the γ″ precipitates. Hardness measurements and <span style=\"color:red\">lifetime</span> measurements are in good agreementr","authors":[{"authorName":"M.Ahmad","id":"0cca0953-69fc-4559-a3bf-33f168681bbc","originalAuthorName":"M.Ahmad"},{"authorName":" W.Ahmad","id":"a0d86f26-b4b3-4727-8cd1-fd0f3419dfa0","originalAuthorName":" W.Ahmad"},{"authorName":" M.A.Shaikh","id":"1d156021-0f49-4228-956d-5776fde6b94f","originalAuthorName":" M.A.Shaikh"},{"authorName":" Mahmud Ahmad","id":"ab1d054e-efd4-4393-9cf6-125455dcbec2","originalAuthorName":" Mahmud Ahmad"},{"authorName":" M.U.Rajput","id":"bc757ae2-cdef-4dfe-b953-6319e9fd90bb","originalAuthorName":" M.U.Rajput"}],"categoryName":"|","doi":"","fpage":"434","id":"81b0ac0f-7c01-4852-82e0-c512a0ef10af","issue":"5","journal":{"abbrevTitle":"CLKXJSY","coverImgSrc":"journal/img/cover/JMST.jpg","id":"11","issnPpub":"1005-0302 ","publisherId":"CLKXJSY","title":"材料科学技术（英文）"},"keywords":[{"id":"d35502c9-04c7-471e-bf67-24f22f59d533","keyword":"Positron <span style=\"color:red\">lifetime</span>","originalKeyword":"Positron lifetime"},{"id":"2551562e-7341-4224-bd37-79561a695a6e","keyword":"null","originalKeyword":"null"},{"id":"435e42da-aa6d-44fc-b898-03bfbdf1f4b5","keyword":"null","originalKeyword":"null"},{"id":"b29d57ee-e9da-45a4-96d8-1bc4989194e9","keyword":"null","originalKeyword":"null"},{"id":"96f7d330-c97f-449c-963f-ba77714a84c0","keyword":"null","originalKeyword":"null"}],"language":"en","publisherId":"1005-0302_2003_5_24","title":"Precipitation Study in Inconel 625 Alloy by Positron Annihilation <span style=\"color:red\">Spectroscopy</span>","volume":"19","year":"2003"},{"abstractinfo":"The effects of <span style=\"color:red\">vacancies</span> on diffusion of interstitial and substitutional atoms as well asinteraction between them in <span style=\"color:red\">metals</span> were discussed.In the interstitial alloy,a coupling betweeninterstitial atoms and vacancy is interrelated through the reaction of formation anddissociation of complex.For substitutional alloy with E_b<kT,if the atom diffusion is of thevacancies exchange mechanism,the <span style=\"color:red\">vacancies</span> may considerably affect atom diffusion.Basedon the micromechanism of diffusion in these two alloys,their diffusion equations under generalcondition may be obtained,and the second Fick' s law is only an approximate form when neg-lecting vacancy influence.","authors":[{"authorName":"ZHANG Sanhong HE Xinlai CHU Youyi KE Jun (T.Ko) University of Science and Technology Beijing","id":"ff792562-c135-4b97-ae7e-ff0d6cb08bfd","originalAuthorName":"ZHANG Sanhong HE Xinlai CHU Youyi KE Jun (T.Ko) University of Science and Technology Beijing"},{"authorName":"China Doctor","id":"2c972ed4-5ca6-444a-b39f-b5a36b6ab0b1","originalAuthorName":"China Doctor"},{"authorName":"Department of Materials Physics","id":"38f04201-3352-41a4-a6ce-a7c9223e9b62","originalAuthorName":"Department of Materials Physics"},{"authorName":"University of Science and Technology Beijing","id":"20ceb3fa-24c6-4750-9a92-02f123928dd4","originalAuthorName":"University of Science and Technology Beijing"},{"authorName":"Beijing 100083","id":"e44570e0-9043-4185-9f20-63153e9bfd2a","originalAuthorName":"Beijing 100083"}],"categoryName":"|","doi":"","fpage":"395","id":"e2241fbc-5395-4997-8ae2-e736ff671c9c","issue":"6","journal":{"abbrevTitle":"JSXBYWB","coverImgSrc":"journal/img/cover/amse.jpg","id":"49","issnPpub":"1006-7191","publisherId":"JSXBYWB","title":"金属学报(英文版)"},"keywords":[{"id":"f0350fdb-dda1-415d-93f2-403c8c711b37","keyword":"vacancy","originalKeyword":"vacancy"},{"id":"7a5d3fe0-9a5f-4d40-b986-b149e28b1c40","keyword":"null","originalKeyword":"null"},{"id":"53735470-d1b3-4d57-afb2-00f3847b695f","keyword":"null","originalKeyword":"null"}],"language":"en","publisherId":"1006-7191_1992_6_4","title":"BEHAVIOUR OF VACANCY INFLUENCE DURING DIFFUSION IN <span style=\"color:red\">METALS</span>","volume":"5","year":"1992"}],"totalpage":254,"totalrecord":2537}