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Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 154-168页

作者： Fei Weng Guijun Bi Youxiang Chew Shang Sui Chaolin Tan Zhenglin Du Jinlong Su Fern Lan Ng key laboratory for Liquid-Solid Structural Evolution and Processing of materials Ministry of EducationShandong Engineering&Technology Research Center for Superhard MaterialSchool of Materials Science and EngineeringShandong UniversityJinan 250061China Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou 510095China Singapore Institute of Manufacturing Technology 5 Cleantech Loop636732Singapore

The feasibility of manufacturing Ti-6Al-4V samples through a combination of laser-aided additive manufacturing with powder(LAAM_(p))and wire(LAAM_(w))was explored.A process study was first conducted to successfully circumvent defects in Ti-6Al-4V deposits for LAAM_(p) and LAAM_(w),*** the optimized process parameters,robust interfaces were achieved between powder/wire deposits and the forged substrate,as well as between powder and wire *** characterization results revealed the epitaxial prior β grains in the deposited Ti-6Al-4V,wherein the powder deposit was dominated by a finerα′microstructure and the wire deposit was characterized by lamellar α *** mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and *** mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications(AMS 6932)even without post heat *** fracture occurred within the interfacial area,further suggesting the robust *** findings of this study highlighted the feasibility of combining LAAM_(p) and LAAM_(w) in the direct manufacturing of Ti-6Al-4V parts in accordance with the required dimensional resolution and deposition rate,together with sound strength and ductility balance in the as-built condition.

关键词： laser-aided additive manufacturing powder deposition wire deposition interfacial characteristic mechanical behavior

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High pressure structural phase transitions of TiO_2 nanomaterials

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Chinese Physics B 2016年第7期25卷 22-30页

作者：李全军刘冰冰 State key laboratory of superhard materials Jilin University

Recently, the high pressure study on the TiO_2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO_2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO_2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO_2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO_2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets,and nanoporous materials, and pressure-induced amorphization（PIA） and polyamorphism in ultrafine nanoparticles and TiO_2-B nanoribbons. Various TiO_2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO_2 nanoribbons, α-PbO_2-type TiO_2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO_2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO_2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications.

关键词： high pressure nanomaterials phase transition TiO2

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Crystal structure and ionic conductivity of Mg-doped apatite-type lanthanum silicates La_(10)Si_(6-x) Mg_x O_(27-x)(x=0–0.4)

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Chinese Physics B 2014年第4期23卷 663-668页

作者：尹广超殷红仲林红孙美玲张俊凯谢晓君丛日东王欣高伟崔啟良 State key laboratory of superhard materials Jilin University

Lanthanum silicates LaloSi6 xMgxO27_x （x = 0-0.4） were prepared by solid state synthesis to investigate the effect of Mg doping on crystal structure and ionic conductivity. Rietveld analysis of the powder XRD patterns reveals that Mg substitution on Si site results in significant enlargement of channel triangles, favoring oxide-ion conduction. Furthermore, an increase of Mg concentration significantly influences the linear density of interstitial oxygen, which plays an important role in ionic conductivity. The Arrhenius plots of LaloSi6_xMgxO27 x （x = 0-0.4） suggest that Mg-doped samples present higher conductivity and lower activation energy than non-doped La10Si6027, and LaloSis.8Mgo.2026.8 exhibits the highest conductivity with a value of 3.0× 10-2 S .cm 1 at 700 ℃. Such conductive behavior agrees well with the refined results. The corresponding mechanism has been discussed in this paper.

关键词： solid oxide fuel cells electrolyte ionic conduction

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In-situ high-pressure behaviors of double-perovskite Sr_2ZnTeO_6

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Chinese Physics B 2013年第5期22卷 644-649页

作者：韩丹丹高伟李娜娜唐瑞莲李会马艳梅崔启良朱品文王欣 State key laboratory of superhard materials Jilin University

Structural and spectroscopic properties of Sr2ZnTeO6 （SZTO） were investigated by angle-dispersive synchrotron X- ray powder diffraction and Raman spectroscopy in a diamond anvil cell up to 31 GPa at room temperature. Although SZTO remained stable up to the highest pressure, the different pressure coefficients of the normalized axial compressibility were obtained as βab=8.16×10-3 GPa-1 andβc=7.61 x 10-3 GPa-1. The bulk modulus B0 was determined to be 190（1） GPa by fitting the pressure-volume data using the Birch-Mumaghan equation of state. All the observed Raman modes exhibited a broadening effect under high pressure. The vibrational band V1 around 765 cm-1, which is associated with the Te-O stretching mode in the basal plane of the TeO6 octahedron had the largest pressure coefficient, and the Griineisen parameters for all the observed phonon modes were also calculated and presented. These parameters could be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for monitoring the magnitude of the shift of phonon frequencies with strains.

关键词： crystal structure high pressure X-ray diffraction optical spectroscopy

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Preferred orientations of encapsulated C_(60) molecules inside single wall carbon nanotubes

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Chinese Physics B 2013年第7期22卷 369-376页

作者：姚震刘然马凤仙路双臣田夫波段德芳崔田刘冰冰 State key laboratory of superhard materials Jilin University

A systematical study of the orientational behavior of C60 molecules in single wall carbon nanotubes （SWCNTs） with different chirality and diameter has been performed by using a model of an infinite long nanotube filled with two C60 （denoted as C60-1 and C60-2） molecules. We studied the preferred orientation of the C60-1 molecule when the neighboring C60-2 molecule was fixed at the pentagon, double-bond, and hexagon orientations respectively. Our results showed that the C60-1 molecule prefers the pentagon （hexagon） orientation when the tube diameter is smaller （larger） than 1.31nm （1.36nm）. For the tube diameter in between, the preferred molecular orientation of C60-1 changes from pentagon to hexagon with the increasing tube diameter when the neighboring C60-2 molecule is fixed at the pentagon or double-bond orientation. A novel vertex orientation for the C60-1 molecule has been found when the C60-2 molecule is fixed at the hexagon orientation.

关键词： peapod C60 nanotube orientation

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Doping effects on structural and magnetic evolutions of orthoferrite SmFe_((1-x) )Al_x O_3

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Chinese Physics B 2014年第4期23卷 438-443页

作者：李娜娜李会唐瑞莲韩丹丹赵永胜高伟朱品文王欣 State key laboratory of superhard materials Jilin University

The structural and magnetic properties of SmFeO3 with B site substitution of non-magnetic atom A1 are investigated. The x-ray diffraction patterns show that SmFe（1-x）AlxO3 remains an orthorhombic structure within the whole doping range, and the unit-cell volume decreases monotonically with the increase of doped A1 concentration. Besides, the octa- hedral tilting distortions of FeO6 are found to be alleviated while the tolerance factor increases. However, the relationship between the lattice parameters and Al concentration is observed to deviate from Vegard＇s rule, and this may be caused by magnetostriction effects. For the doping content values in a range 0 〈 x 〈 0.6, the ferromagnetism, antiferromagnetism, and paramagnetism are observed to occur continuously. Moreover, the magnetization and the spin reorientation temperature （Tk） decrease monotonically as Al content value increases. With the doping content values being x = 0.8 and 1.0, these compounds only show paramagnetic behavior.

关键词： magnetic materials X-ray diffraction magnetic properties

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Controllable synthesis of fullerene nano/microcrystals and their structural transformation induced by high pressure

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Chinese Physics B 2013年第9期22卷 135-146页

作者：姚明光杜明润刘冰冰 State key laboratory of superhard materials Jilin University

Fullerene molecules are interesting materials because of their unique structures and properties in mechanical, electrical, magnetic, and optical aspects. Current research is focusing on the construction of well-defined fullerene nano/microcrystals that possess desirable structures and morphologies. Further tuning the intermolecular interaction of the fullerene nano/microcrystals by use of pressure is an efficient way to modify their structures and properties, such as creation of nanoscale polymer structures and new hybrid materials, which expands the potential of such nanoscale materials for di- rect device components. In this paper, we review our recent progress in the construction of fullerene nanostructures and their structural transformation induced by high pressure. Fullerene nano/microcrystals with controllable size, morphology and structure have been synthesized through the self-assembly of fullerene molecules by a solvent-assisted method. By virtue of high pressure, the structures, components, and intermolecular interactions of the assemblied fullerene nano/microcrystals can be finely tuned, thereby modifying the optical and electronic properties of the nanostructures. Several examples on high pressure induced novel structural phase transition in typical fullerene nanocrystals with C60 or C70 cage serving as build- ing blocks are presented, including high pressure induced amorphization of the nanocrystals and their bulk moduli, high pressure and high temperature （HPHT） induced polymerization in C60 nanocrystals, pressure tuned reversible polymeriza- tion in ferrocene-doped C60/C70 single crystal, as well as unique long-range ordered crystal with amorphous nanoclusters serving as building blocks in solvated C60 crystals, which brings new physical insight into the understanding of order and disorder concept and new approaches to the design of superhard carbon materials. The nanosize and morphology effects on the transformations of fullerene nanocrystals have a

关键词： fullerenes nanocrystals high pressure polymerization structural transitions

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Theoretical design of diamondlike superhard structures at high pressure

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Chinese Physics B 2016年第7期25卷 1-8页

作者：李全郑伟涛 Department of materials Science Key Laboratory of Automobile Materials of MOE and State Key Laboratory of Superhard MaterialsJilin University

Diamond, as the hardest known material, has been widely used in industrial applications as abrasives, coatings, and cutting and polishing tools, but it is restricted by several shortcomings, e.g., its low thermal and chemical stability. Considerable efforts have been devoted to designing or synthesizing the diamond-like B-C-N-O compounds, which exhibit excellent mechanical property. In this paper, we review the recent theoretical design of diamond-like superhard structures at high pressure. In particular, the recently designed high symmetric phase of low-energy cubic BC3 meets the experimental observation, and clarifies the actual existence of cubic symmetric phase for the compounds formed by B-C-N-O system,besides the classical example of cubic boron nitride.

关键词： crystal structures high pressure superhard materials

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In-situ high pressure X-ray diffraction studies of orthoferrite SmFeO_3

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Chinese Physics B 2014年第6期23卷 635-638页

作者：李娜娜李岩李会唐瑞莲赵永胜韩丹丹马艳梅崔启良朱品文王欣 State key laboratory of superhard materials Jilin University

The high-pressure behaviors of SmFeO3 are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO3 remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be βa = 0.60 × 10-3 GPa-1,βb = 0.79 × 10-3 GPa-1, βc = 1.28 × 10-3 GPa- 1, and the bulk modulus （B0） is determined to be 293（3） GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. Furthermore, the larger compressibility of the FeO6 octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures.

关键词： crystal structure high-pressure X-ray diffraction

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Growth and annealing study of hydrogen-doped single diamond crystals under high pressure and high temperature

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Chinese Physics B 2012年第5期21卷 652-656页

作者：李勇贾晓鹏胡美华刘晓兵颜丙敏周振翔张壮飞马红安 State key laboratory of superhard materials Jilin University

A series of diamond crystals doped with hydrogen is successfully synthesized using LiH as the hydrogen source in a catalyst-carbon system at a pressure of 6.0 GPa and temperature ranging from 1255 C to 1350 *** is shown that the high temperature plays a key role in the incorporation of hydrogen atoms during diamond *** transform infrared micro-spectroscopy reveals that most of the hydrogen atoms in the synthesized diamond are incorporated into the crystal structure as sp 3-CH 2-symmetric（2850 cm-1） and sp 3 CH 2-antisymmetric vibrations（2920 cm-1）.The intensities of these peaks increase gradually with an increase in the content of the hydrogen source in the *** incorporation of hydrogen impurity leads to a significant shift towards higher frequencies of the Raman peak from 1332.06 cm-1 to 1333.05 cm-1 and gives rise to some compressive stress in the diamond crystal ***,hydrogen to carbon bonds are evident in the annealed diamond,indicating that the bonds that remain throughout the annealing process and the vibration frequencies centred at 2850 and 2920 cm-1 have no observable ***,we suggest that the sp 3 C-H bond is rather stable in diamond crystals.

关键词： high pressure and high temperature hydrogen-doped diamond crystals annealing LiH additives

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