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THE MICROSTRUCTURE AND COMPRESSIVE PROPERTIES IN NiAl(Co) MATRIX COMPOSITE

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Acta Metallurgica Sinica(English letters) 1996年第6期9卷 653-657页

作者： l.Chen Y.F. Han C.H Tao and M.l. Xie(Beijing Institute of Aeronautical Materials, Beijing 100095, ) Beijing Inst of Aeronautical Materials Beijing China

The microstructures of NiAl(Co)-TiB_2 composite prepared using exothermal dispersion (XD) method have been studied by optical microscopy, XRD, EDS, and TEM The results show that, TiB_2 paritcles are typically single crystal, and fairly uniformly distributed. The matrix mainly consists of β-NiAl phase, ll_2γ′Ni_3Al phase and δ-Ni_3Al phase. The δNi_3Al has a fcc crystal structure with lattice parameter a=*** data of compressive testing at room temperature show that the room temperature ductility of NiAl(Co) matrix composite is much better than that of stoichiometric NiAl.

关键词： intermetallic compound exothermal dispersion method

Tuning the melting point and phase stability of rare-earth oxides to facilitate their crystal growth from the meltv

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Journal of Advanced Ceramics 2022年第9期11卷 1479-1490页

作者： Matheus PIANASSOlA Kaden l.ANDERSON Joshua SAFIN Can AGCA Jake W.MCMURRAY Bryan C.CHAKOUMAKOS Jöerg C.NEUEFEIND Charles l.MElCHER Mariya ZHURAVlEVA Scintillation Materials Research Center The University of TennesseeKnoxville 37996USA Department of Materials Science and Engineering The University of TennesseeKnoxville 37996USA Materials Science and Technology Division Oak Ridge National LaboratoryOak Ridge 37831USA Neutron Scattering Division Oak Ridge National LaboratoryOak Ridge 37831USA Department of Nuclear Engineering The University of TennesseeKnoxville 37996USA

The challenge of growing rare-earth(RE)sesquioxide crystals can be overcome by tailoring their structural stability and melting point via composition *** work contributes to the advancement of the field of crystal growth of high-entropy oxides.A compound with only small REs(lu,Y,Ho,Yb,Er)_(2)O_(3)maintains a cubic C-type structure upon cooling from the melt,as observed via in-situ high-temperature neutron diffraction on aerodynamically levitated *** the other hand,a compound with a mixture of small and large REs(lu,Y,Ho,Nd,la)_(2)O_(3)crystallizes as a mixture of a primary C-type phase with an unstable secondary *** of compositions(lu,Y,Ho,Nd,la)_(2)O_(3)and(lu,Y,Gd,Nd,la)_(2)O_(3)were grown by the micro-pulling-down(mPD)method with a single monoclinic B-type phase,while a powder of(lu,Y,Ho,Yb,Er)_(2)O_(3)did not melt at the maximum operating temperature of an iridium-rhenium *** minimization of the melting point of the two grown crystals is attributed to the mismatch in cation *** electron probe microanalysis reveals that the general element segregation behavior in the crystals depends on the composition.

关键词： high-entropy oxides crystallography neutron diffraction crystal growth

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不同取向镍基单晶高温合金650℃原位拉伸

电子显微学报 2024年第3期43卷 295-302页

作者：李菲祺吕俊霞程晓鹏王晋张跃飞张泽北京工业大学材料与制造学部北京100124 浙江大学材料科学与工程学院浙江杭州310027

镍基单晶高温合金作为飞机涡轮发动机叶片的主要使用材料,其在服役过程中受到各向应力作用产生变形导致材料失效,因此本文基于课题组自主研发的原位拉伸设备对[140]取向、[340]取向、[122]取向的镍基单晶高温样品进行了650℃原位拉伸。... 详细信息

镍基单晶高温合金作为飞机涡轮发动机叶片的主要使用材料,其在服役过程中受到各向应力作用产生变形导致材料失效,因此本文基于课题组自主研发的原位拉伸设备对[140]取向、[340]取向、[122]取向的镍基单晶高温样品进行了650℃原位拉伸。其中[140]取向样品在屈服阶段后样品硬化到塑性变形后期出现了幅度较小的应力下降,最后样品在应力作用下滑移迹线所在的基体发生开裂,裂纹沿着滑移迹线所在方向扩展至样品断裂。[340]取向样品在整个塑性变形阶段,样品的应力持续下降,孔洞缺陷处形成缺陷导致材料失效。[122]取向样品一直处于硬化阶段,到塑性变形后期样品出现了应力的下降,跟[340]取向样品失效方式相同,孔洞开裂形成裂纹源导致材料失效。本文针对三种取向样品的力学性能,塑性变形过程中的滑移情况以及对应的施密特因子变化、样品失效的方式进行了分析,对合金在真实服役过程中提高其服役寿命具有重要意义。

关键词：镍基单晶高温合金原位拉伸滑移分析力学性能

Stress-rupture behavior of a Re-containing Ni-base single crystal superalloy at high temperatures

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Journal of Materials Science & Technology 2023年第32期163卷 237-244页

作者： G.l.Wang D.Q.Qi J.l.liu J.D.liu J.G.li Y.Z.Zhou X.F.Sun Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

A Re-containing Ni-base single crystal superalloy was used to investigate the elementary processes associated with stress-rupture behavior at different temperatures where theγʹrafting *** 900°C,the rupture behavior is mainly determined by the multiplication of dislocations within the wideningγchannels,which is closely linked with the propagation of microcracks along the inherentγ/γʹ*** rapid formation of lamellaγ/γʹraft structure,along with the developed-well interfacial dislocation networks,and its elastic instability are primarily responsible for the rupture behavior at 1100°*** is a clear curvature tendency in the larson-Miller plot of stress-rupture lifetime in relation to stress at high *** indicates that the influence extent ofγʹrafting on stress-rupture behavior is sensitive to the acting conditions of temperature and stress.

关键词： Ni-based single crystal superalloy Re effect γʹrafting Stress-rupture behavior Elementary process larson-Miller plot

Effects of varying Alx moles on structure and luminescence properties of ZnAl_(x)O_(1.5x+1):0.1 mol%Tb^(3+)nanophosphors prepared using citrate sol-gel method

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Journal of Rare Earths 2023年第3期41卷 358-364,I0002页

作者： V.M.Maphiri l.T.Melato M.R.Mhlongo T.T.Hlatshwayo T.E.Motaung l.F.Koao S.V.Motloung Department of Physics Sefako Makgatho Health Science UniversityP.O.Box 94Medunsa0204South Africa Department of Mathematics Non Destructive Testing and PhysicsVaal University of TechnologyAndries Potgieter BlvdVanderbijlpark1900South Africa Department of Physics University of PretoriaPretoria0002South Africa Department of Chemistry School of Science in the College of Science Engineering and TechnologyUniversity of South AfricaPreller StreetMuckleneuk RidgeCity of TshwaneP.O Box 392UNISA 0003South Africa Department of Chemistry Sefako Makgatho Health Science UniversityP.O.Box 94Medunsa0204South Africa Department of Physics University of the Free State(Qwaqwa Campus)Private Bag X13Phuthaditjhaba 9866South Africa Department of Chemical and Physical Sciences Walter Sisulu UniversityMthathaSouth Africa

Un-doped and ZnAl_(x)O_(1.5x+1):0.1 mol%Tb^(3+)(ZAOT)nano-powders were synthesized via citrate sol-gel *** AIx moles were varied in the range of 0.25≤x≤*** X-ray powder diffraction(XRD)data reveal that for xles crystal structure consists of mixed phases of the cubic ZnAl_(2)O_(4) and hexagonal ZnO phases,while for x>1.5 the structure consists of single phase of cubic ZnAl_(2)O_(4).The Raman and Fourier-trans form infrared(FTIR)vibrational spectroscopy show the presence of vibrations emanating ZnAl_(2)O_(4) *** electron microscopy(SEM)and transmission electron microscopy(TEM)show the presence of irregular sphere at x>2.0 attributed to ZnAl_(2)O_(4).The photoluminescence(Pl)spectroscopy reveals emissions from both the host and Tb^(3+)*** from Tb^(3+)are observed at 382,414,439,458 nm and 489,545,585,621 nm,which were attributed to the^(5)D_(3)→^(7)F_(6,5,4,2) and ^(5^)D_(4)→^(7)F_(6,5,4,3),*** results confirm that the Tb^(3+)occupation site depends on the Alx *** International Commission on Illumination(CIE)colour chromaticity shows that the emission colour can be tuned from blue to green by varying the AIx moles.

关键词： Citrate sol-gel ZnAl_(2)O_(4)/ZnO Tb^(3+)-doped Al_(x)moles Photoluminescence Rare earths

A novel direct reduction method to synthesize ordered Fe-Pt alloy nanoparticles

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Journal of Materials Science & Technology 2019年第4期35卷 560-567页

作者： Q.Zheng Z.R.Zhang J.Du l.l.lin W.X.Xia J.Zhang B.R.Bian J.P.liu School of Materials and Chemical Engineering Ningbo University of Technology CAS Key laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology & EngineeringChinese Academy of Sciences Department of Physics University of Texas at Arlington

In this work, a direct green solid-phase reduction method for the fabrication of large yield of ordered phase Fe-Pt alloy nanoparticles was reported, in which inorganic salts were used as metal precursors and H_2-containing atmosphere was used as reducer. Utilizing this method, the composition and chemical ordered phase, such as l1_2-Fe_3 Pt, l1_2-FePt_3, and l1_0-FePt phases can be easily achieved by one step reaction. The synthesized nanoparticles have clean surface because no organic precursors, no organic solutions or organic surfactants/ligands were used. Their magnetic performance and the formation mechanism of Fe-Pt alloy nanoparticles were also investigated. This strategy can be applied to synthesize many other types of alloy nanoparticles with desired composition and necessary crystal structure, which can be used for a variety of practical applications, such as in magnetism and catalyst research fields.

关键词： Magnetic nanoparticles FePt Chemical synthesis

The structure of Rap1 in complex with RIAM reveals specificity determinants and recruitment mechanism

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Journal of Molecular Cell Biology 2014年第2期8卷 128-139页

作者： Hao Zhang Yu-Chung Chang Mark l. Brennan Jinhua Wu Developmental Therapeutics Program Fox Chase Cancer Center 333 Cottman Avenue Philadelphia PA 19111 USA

The small GTPase Rap1 induces integrin activation via an inside-out signaling pathway mediated by the Rapl-interacting adaptor mol- ecule （RIAM）. Blocking this pathway may suppress tumor metastasis and other diseases that are related to hyperactive integrins. However, the molecular basis for the specific recognition of RIAM by Rap1 remains largely unknown. Herein we present the crystal structure of an active, GTP-bound GTPase domain of Rap1 in complex with the Ras association （RA）-pleckstrin homology （PH） structural module of RIAM at 1.65 A. The structure reveals that the recognition of RIAM by Rap1 is governed by side-chain interactions. Several side chains are critical in determining specificity of this recognition, particularly the lys31 residue in Rap1 that is oppositely charged compared with the Glu31/Asp31 residue in other Ras GTPases. lys31 forms a salt bridge with RIAM residue Glu212, making it the key specificity determinant of the interaction. We also show that disruption of these interactions results in reduction of Rapl：RIAM association, leadingto a loss of co-clustering and cell adhesion. Our findings elucidate the molecular mechanism by which RIAM med- iates Rapl-induced integrin activation. The crystal structure also offers new insight into the structural basis for the specific recruitment of RA-PH module-containing effector proteins by their smaU GTPase partners.

关键词： RIAM Rap1 integrin signaling inside-out signaling crystal structure RA-PH

crystal structure and magnetic properties of YbZn_(0.7)In_(1.3)

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Journal of Rare Earths 2011年第10期29卷 943-945页

作者： Yu.Verbovytskyy l.C.J.Pereira A.P.Gon alves Department of Chemistry Nuclear and Technological InstituteNational Rd.102686-953SacavémPortugal

The new ternary YbZn0.7Inl.3 compound was synthesized in evacuated quartz ampoules at 900 ℃, followed by annealing at 400 ℃. It crystallized in the UHg2 structure type with a=0.47934（5） nm, c=0.36955（5） nm, V=0.073535（15） nm3. The shortest distances between the atoms in this structure were equal to 0.3696 nm （Yb-Yb）, 0.3328 nm （Yb-M） and 0.2767 nm （M M）, respectively. Magnetization measurements indicated that the title compound exhibited a paramagnetic behavior down to 2 K, with antiferromagnetic-like interactions. Calculated magnetic moment for YbZn0.7inl.3 （μeft =3.86μB/Yb） could indicate mixed valence state of Yb.

关键词： ytterbium intermetallics crystal structure magnetic measurements rare earths

掺铒CaF_(2)、SrF_(2)、PbF_(2)晶体的光谱性能与团簇结构研究

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无机材料学报 2024年第3期39卷 330-336,I0009,I0010页

作者： TAM YU Puy Mang 徐愉高泉浩周海琼张振尹浩李真吕启涛陈振强马凤凯苏良碧暨南大学光电工程系广东省晶体材料与激光技术工程研究中心广州510632 广东省光纤传感与通信重点实验室广州510632 暨南大学分析测试中心广州510632 中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室上海201899 广东省工业超短脉冲激光技术重点实验室深圳518055

3μm波段中红外激光处于大气传输窗口,又可以作为基础光源,是激光技术研究的前沿。目前,铒离子激活的激光晶体材料是产生3μm中红外激光的重要途径之一。然而,Er3+离子4I11/2激光上能级荧光寿命较短,下能级4I13/2的寿命较长,难以实现粒... 详细信息

3μm波段中红外激光处于大气传输窗口,又可以作为基础光源,是激光技术研究的前沿。目前,铒离子激活的激光晶体材料是产生3μm中红外激光的重要途径之一。然而,Er3+离子4I11/2激光上能级荧光寿命较短,下能级4I13/2的寿命较长,难以实现粒子数反转,导致自终止现象。为了解决这一难题,往往需要高浓度掺杂,通过能量传递降低4I13/2能级的寿命。然而高浓度掺杂又会造成晶体热性能变差,限制了掺Er3+激光晶体效率和功率。三阶铒离子容易在氟化物晶体中形成团簇,导致稀土离子间距缩短,即使在低掺杂浓度下稀土离子之间的能量传递作用仍较为显著。同时,低浓度掺杂还可以减轻激光运转下晶体的热堆积效应。掺铒氟化物晶体已成为一类重要的高功率、高效率中红外激光材料。然而,掺铒氟化物晶体的光谱性能与铒离子团簇结构之间的相互联系尚不明确,制约了掺铒氟化物晶体光谱和激光性能的进一步发展。本文采用第一性原理计算模拟了铒离子在CaF_(2)、SrF_(2)和PbF_(2)晶体中的团簇结构。结果显示,铒离子团簇结构随基质晶体变化逐渐演变。结合模拟计算和实验表征定性揭示了不同晶体离子团簇与光谱性能的联系,为掺铒氟化物中红外激光晶体材料的调控与设计提供参考。

关键词：铒掺杂氟化物晶体铒离子团簇光谱性能