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  • 1
    Electronic Resource
    Electronic Resource
    Growth Characteristic and Fracture Toughness of Laser Rapidly Solidified Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/YAG/ZrO〈sub〉2〈/sub〉 Ceramic Eutectic 〈i〉In Situ〈i〉 Composite (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 495-500 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Directionally solidified oxide ceramic eutectic composites with superior strength,oxidation resistance, creep resistance, structural stability and low sensitivity to crack at hightemperature have aroused much attention in recent years, and various preparation techniques havebeen developed. In situ fabrication of ceramic eutectic composites by laser rapid solidification is acheap and quick method compared to conventional multi-step fabrication methods of fiber reinforcedcomposites for high temperature use. In this paper, Al2O3/YAG/ZrO2 ternary eutectics are rapidlyprepared from melt by directional solidification using laser zone remelting technique, the growthcharacteristic and fracture toughness are investigated. The results show that: (1) Laser rapidlysolidified Al2O3/YAG/ZrO2 ceramic eutectic in situ composite presents a fine interpenetratingnetwork structure, in which Al2O3, YAG and ZrO2 phases are continually interconnected and finelycoupled without pores, colonies and grain boundaries between interfaces. (2) Laser scanning rate andpower density strongly affect the eutectic growth. With the processing parameters adjusted properly,the eutectic shows homogeneous and coupled lamellar microstructure. The characteristic dimensionsof the microstructure are around 2~3 1m for Al2O3 and YAG phases, and around 0.2~1 1m for ZrO2phases, respectively. (3) The hardness and fracture toughness of the rapidly solidifiedAl2O3/YAG/ZrO2 eutectic are 16.7 GPa and 8.0 MPa.m1/2, respectively
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.495.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Laser Zone-Remelted Alumina-Based Eutectic In Situ Composite (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 539-543 (Mar. 2007), p. 832-836 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Due to excellent oxidation and corrosion resistance at elevated temperature, oxide ceramiccould be the preference served at high temperature oxidizing atmosphere over a long period of time.In recent years, alumina-based eutectic in situ composite prepared by various solidificationtechniques, which has superior properties even close to the melting point about 2100K, has been paidmuch attention. In this paper, Al2O3/YAG/ZrO2 ternary eutectic and hypoeutectic ceramics areprepared from melt by laser zone-remelting technique, the rapid solidification characteristic and themechanical property of the composites are investigated. The results show that: (1) Compared tosintered composite with the same composition, laser zone-remelted Al2O3/YAG/ZrO2 eutectic in situcomposite has different microstructure showing fine interpenetrated network with Al2O3, YAG andZrO2 phases continuously intergrown, while none of pores, grain boundaries and amorphous phasesis found. (2) The scanning rate and the power density of the laser beam has strong effect on themicrostructure morphology. When the power density is determined, the eutectic spacing is reducedwith the scanning rate increased. The characteristic eutectic spacings and phase sizes of YAG andAl2O3 are about 2~3μm, and the characteristic dimension of ZrO2 is less than 1μm. (3) The hardnessand the room-temperature fracture toughness of Al2O3/YAG/ZrO2 eutectic are respectivelyHv=16.7±2.0 GPa and KIC=8.0±2.0 MPa.m1/2, and those of hypoeutectic are respectivelyHv=15.8±2.0 GPa and KIC=3.9±1.0 MPa.m1/2
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.832.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Microstructure and Mechanical Properties of an Advanced Niobium Based Ultrahigh Temperature Alloy (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 539-543 (Mar. 2007), p. 3690-3695 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The microstructure and mechanical properties including room temperature fracturetoughness Kq, tensile strengthσb and elongationδ at 1250℃ of the Nb based alloy directionallysolidified in an electron beam floating zone melting (EBFZM) furnace have been evaluated. Themicrostructure is primarily composed of Nb solid solution (Nbss), α-(Nb)5Si3 and (Nb)3Si phases.After directional solidification with the moving rate of electron beam gun R being respectively 2.4,4.8 and 7.2 mm/min, the primary Nbss dendrites, Nbss + (Nb)5Si3/(Nb)3Si eutectic colonies(lamellar or rod-like) and divorced Nb silicide plates align along the longitudinal axes of thespecimens. When R = 2.4 mm/min, the best directional microstructure is obtained. Directionalsolidification has significantly improved theσb at 1250℃ and Kq. The maximumσb occurs for thespecimens with R = 2.4 mm/min and is about 85.0 MPa, meanwhile, the Kq is about 19.4 MPam1/2
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.3690.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Microstructure Evolution of Ti-Al Peritectic System during the Initiated Stage of Directional Solidification (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1447-1450 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The microstructure evolution of Ti-Al peretectic system in transient stage and steady statein directional solidification was predicted via theoretical analysis. The solute distribution controlledby diffusion at and ahead the solid-liquid interface will determine whether the properitectic andperitectic phases can nucleate and grow ahead of the opposing solid phase. The formation of bandingstructure is possible in a certain composition range. At the steady state, a microstructure selection mapwas set up based on interface response function model. The microstructure of TiAl alloys withdifferent aluminum content was studied with Bridgman directional solidification method. Someevidence in the experiment has been found to support the theoretical prediction
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/16/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.546-549.1447.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Microstructure and Mechanical Property of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Y〈sub〉3〈/sub〉Al〈sub〉5〈/sub〉O〈sub〉12〈/sub〉 (YAG) Eutectic Ceramic In Situ Composite Prepared by Laser Zone Melting (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 561-565 (Oct. 2007), p. 999-1002 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Directionally solidified Alumina-based eutectic ceramic in situ composite is a kind ofpromising candidate for high temperature structural material applied at elevated temperature above1923K because of its excellent properties. With laser zone melting directional solidification,Al2O3/Y3Al5O12 (YAG) eutectic ceramics are successfully prepared. The relationship between theeutectic microstructure and the processing parameter is studied, and the mechanical property of thecomposite is measured. The results show that: (1) Laser power density and scanning rate stronglyaffect the eutectic microstructure. With proper processing parameters adjusted, the binary lamellareutectic microstructure is obtained, in which Al2O3 and YAG phases are three-dimensionally coupledand continuously connected without grain boundaries and amorphous interface phases. (2) Theeutectic spacing decreases to about 1μm with increasing scanning rate. (3) The maximum hardness of19.5GPa and the room fracture toughness of 3.6MPa.m1/2 are obtained by Vickers indentationmeasurement
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.561-565.999.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Recent Activities on Directional Solidification at the State Key Laboratory of Solidification Processing (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 539-543 (Mar. 2007), p. 3106-3111 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Directional solidification technique permits materials to grow along specificorientation, in order to obtain mechanical and/or physical anisotropy. The present researchattempts to introduce the research work in the field of processing of some advanced materialsby innovative directional solidification techniques performed at State Key Laboratory ofSolidification Processing and with author’s intended research work.The paper deals with the specific topics on state of the art of directional solidification:single crystal superalloy and Nd-Fe-B alloys under high thermal gradient, Cu-Ni alloys underdeep supercooling of the melt.The relevant solidification phenomena, such as morphological evolution, crystal growthfor multi-phases in the processing of directional solidification, are discussed briefly. The trendsof developments of directional solidification techniques are also prospected
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.3106.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis on the Ceasing Mechanism of the YBCO Crystal Growth during Melting Growth Process by Unidirectional Solidification (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 2091-2096 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The unidirectional solidification technology by a zone melting method was performed toobtain the large single domain YBCO. The interface morphology and chemical composition at thegrowth front of the YBCO crystal were investigated in order to make clear the growth characteristic ofthe YBCO crystal during melting growth by unidirectional solidification. It was found that YBCOcrystal would cease growing when yttrium was depleted in the liquid phase at the YBCO crystalgrowth front. For maintaining the continuous growth of YBCO crystal, compositions of Y, Ba and Cuin raw samples have to be adjusted so as to make yttrium rich in the liquid phase at the YBCO crystalgrowth front during the melting growth process. It is very useful for the study on the mechanism of theYBCO crystal growth
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/16/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.546-549.2091.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    Unidirectional Solidification of a Nb〈sub〉ss〈/sub〉/Nb〈sub〉5〈/sub〉Si〈sub〉3〈/sub〉 In-Situ Composite (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 475-479 (Jan. 2005), p. 745-748 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The directionally solidified specimens of Nb-13.52 Si-22.60 Ti–6.88 Hf–2.54 Cr–2.24 Al alloy were prepared in an electron beam floating zone melting furnace at the withdrawing rate of 0.1, 0.3, 0.6, 1.0, 2.4 and 6.0 mm/min. All the primary Nb solid solution (Nbss) columns, Nbss + (Nb)3Si/(Nb)5Si3 eutectic colonies and divorced (Nb)3Si/(Nb)5Si3 plates or chains align well along the longitudinal axis of the specimens. With increasing of the withdrawing rate, the microstructureis gradually refined, and the amount of Nbss + (Nb)3Si/(Nb)5Si3 eutectic colonies increases. Both the room temperature ultimate tensile strength σb and fracture toughness KQ are improved for the directionally solidified specimens. The tensile fracture occurs in a cleavage way
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/09/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.475-479.745.pdf
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  • 9
    Electronic Resource
    Electronic Resource
    Research on the Coupling between Electromagnetic Pressure and Temperature Field in Dual-Frequency Electromagnetic Shaping Process (2003)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 426-432 (Aug. 2003), p. 3855-3860 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/07/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.426-432.3855.pdf
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  • 10
    Electronic Resource
    Electronic Resource
    Investigation on a Fabrication Technique of TiAl Sheet (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 475-479 (Jan. 2005), p. 805-808 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A TiAl sheet fabrication technique from Ti/Al foils was studied experimentally. Firstly, the reaction sequence between Ti and Al foils were studied with DSC and then a three stage solid transformations processing was carried out. At the first stage, Al diffused into Ti foils and formed Al3Ti. The heating temperature was selected based on a ruler that the pure Al was consumed by solid diffusion with a short time and avoiding the melting of Al. The resulted microstructure consists of pure Ti and Al3Ti. At the second stage, part of Al in Al3Ti diffused into pure Ti and formed the high temperature phase. At the third stage, the sample was heated into the high temperature -phase zone and hold a given time and then cooling with the furnace. A full density γ-TiAl based alloy sheet with lamellar microstructure was successfully fabricated under above processing. The lamellar orientations are aligned around 0-45o compared to the longitudinal direction of the sheet
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/09/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.475-479.805.pdf
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