X-Ray Stress Measurement of Composite Material Using Synchrotron Radiation

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JAlloysComp-2006-419(1-2)227

Journal of Alloys and Compounds419(2006)227–233Self-propagating high-temperature synthesis ofTiC–WC composite materialsM.J.Mas-Guindal a,∗,L.Contreras a,X.Turrillas b,G.B.M.Vaughan c,˚A.Kvick c,M.A.Rodr´ıguez aa Instituto de Cer´a mica y Vidrio,CSIC,C/Kelsen,No5,28049Madrid,Spainb Eduardo Torroja Institute for Construction Sciences,CSIC,28033Madrid,Spainc European Synchrotron Radiation Facility,38043Grenoble,FranceReceived7July2005;accepted22August2005Available online18November2005AbstractTiC–WC composites have been obtained in situ by self-propagating high-temperature synthesis(SHS)from a mixture of compacted powders of elemental titanium,tungsten and graphite.The Rietveld method has proved to be a useful tool to quantify the different phases in the reaction and calculate the cell parameters of the solid solution found in the products.The reaction has also been followed in real time by X-ray diffraction at the European Synchrotron Radiation Facility(ESRF ID-11Materials Science Beamline).The mechanism of the reaction is discussed in terms of the diffusion of liquid titanium to yield titanium carbide with a solid solution of tungsten.The microstructures of the materials obtained by this method are presented.©2005Elsevier B.V.All rights reserved.Keywords:Self-propagating high-temperature synthesis;Combustion synthesis;Synchrotron radiation;X-ray diffraction;Carbides1.IntroductionIn this paper,the TiC–WC system is being discussed;char-acteristic of this system is the high hardness of its components (TiC has31GPa Vickers hardness and WC has25GPa),which facilitates its uses as abrasives and cutting and polishing tools among others[1,2].Metcalfe was theﬁrst to report a study on this system[3].The phase diagram at low temperature shows the existence of two main regions(Fig.1):under45mol%of WC a solid solution of(Ti,W)C is formed,in which titanium atoms of the TiC fcc cubic cell are substituted by tungsten atoms.If more than45mol%of WC is present,two phases appear:the solid solution and a phase only formed by hexagonal WC.When temperature is above1600◦C an increase in the degree of solid solution is observed and more tungsten is accepted in solid solu-tion before the appearance of the two phases[4,5].The self-propagating high-temperature synthesis(SHS)is a technique that has proved to be very useful to obtain metallic,∗Corresponding author.Tel.:+34917355840;fax:+34917355843/45.E-mail address:mjmg@icv.csic.es(M.J.Mas-Guindal).ceramic and composite materials with hardness and refractori-ness that make them useful as abrasives,cutting tools,armour of vehicles,thermal barriers,etc.Among these compounds there are borides,carbides,carbonitrides,hydrides,nitrides,silicides and others.The reaction is characterised by a high exothermicity which leads to a self-sustained process.Ignition is usually pro-duced by means of an electric or caloriﬁc device and combustion front propagation is made at high speeds(1–100mm/s),favoured if powders are compacted.As advantages we could mention the low energetic cost,its productivity or the high yields obtained [1,6–11].The objective is to develop a way of predicting the solid solution degree by the calculation of the unit cell parameters and study the phase percentages obtained when different com-positions of TiC–WC are prepared by means of SHS.Reactions to be studied are:4Ti+5C+W→4TiC+WC(I) 3Ti+4C+W→3TiC+WC(II) 2Ti+3C+W→2TiC+WC(III)0925-8388/$–see front matter©2005Elsevier B.V.All rights reserved. doi:10.1016/j.jallcom.2005.08.079228M.J.Mas-Guindal et al./Journal of Alloys and Compounds 419(2006)227–233Fig.1.Binary phase diagram for TiC–WC system (6).Vertical gross lines indicate the localization of the different reactions in the diagram.Ti +2C +W →TiC +WC (IV)Ti +3C +2W →TiC +2WC(V)Also reaction of pure titanium with graphite to give titaniumcarbide was studied as a reference.Additional work has been done using Synchrotron Radiation to try to explain the mecha-nism of the combustion.It has been empirically established that when the adiabatic temperature (T ad )is lower than 1800K,reactions are not self-sustained [6].Calculation of T ad can be done by solving the equation,which comes from the deﬁnition of heat capacity [12]:H = H r ,T 0+T adT 0C p (products)d Twhere H is the reaction enthalpy, H r ,T 0is the enthalpy at T 0(initial temperature,normally 298K)and C p (products)is the heat capacity for the products of the reaction.If the system isadiabatic,then:− H r ,T 0=T adT 0C p (products)d T Using data taken from bibliography [13]and summarised in Table 1we ﬁnd that all reactions proposed can be self-sustaining;however,reaction (V)will have trouble to be self-sustaining for its T ad is below the limit.It is also seen that pure tungsten carbide formation is not self-sustaining (T ad =1000K).On the other hand,pure titanium carbide has a very favoured reaction,as expected by its high T ad (3200K).Thus another advantage of mixing both,titanium and tungsten with carbon,is that tita-nium carbide formation acts as a sort of chemical activator for obtaining tungsten carbide by SHS.The high temperatures reached and the high speeds of com-bustion front propagation make these reactions difﬁcult to fol-low,so little knowledge about the mechanism or kinetics is available.Time resolved X-ray diffraction (TRXRD)using high intensity synchrotron radiation has proved to be very useful forTable 1Thermodynamic data for basic substances [13]SubstanceMelting point (◦C)H ◦298(J/mol)C p (J/mol K)a AB C D Ti 19410.017.83424.376 3.047−8.840W36800.019.30420.7100.385−18.086C (graphite)38200.0−7.09459.1540.799−32.718TiC 3290−184,568.0−97.045667.897 4.587−826.766WC3058−40,180.843.3918.639−9.321−1.021aC p =A +B ×10−3T +C ×105T 2+D ×10−6T 2.M.J.Mas-Guindal et al./Journal of Alloys and Compounds419(2006)227–233229in situ following of the reaction[9–11].For this part of the work,the Materials Science Beamline(ID11)at the European Synchrotron Radiation Facility(ESRF)in Grenoble,France,has been used as a complement to study reaction(I).Finally,the Rietveld reﬁnement method[14]for quantitative phase analysis has been used in diffractograms recorded with conventional X-ray diffraction to obtain the phase percentage of the products and reﬁne the cell parameters in order to obtain the degree of solid solution[15].2.Experimental procedure2.1.Powder preparationThe following starting materials have been used:(a)pure Ti powder>99%(William Rowland Ltd.,UK)with particle size d50=84␮m,(b)graphite pow-der99.6%(Sofacel,Spain)with particle size d50=1.7␮m,(c)pure W powder(William Rowland Ltd.,UK)with particle size d50=1.2␮m.Also,an extra amount of Ti+C was weighted,in the same proportion given,in order to use it as an ignitor of combustion(this way it supplies the necessaryenergy for the starting of the reaction).Powders were mixed in an agata mortar and pressed in a30-mm diameterstainless steel die.A pressure of2MPa was applied to obtain15mm thicknesscylindrical pellets.2.2.Post-reaction studyReactions were made in a SHS reactor and triggered in argon atmosphereusing a tungsten wire and titanium–graphite powder as bed reaction.Pelletswith composition(IV)had to be almost fully covered with the Ti–C powder inorder to make reaction possible.Reaction(V)did not start because of its verylow T ad.2.3.Real-time studyThe ESRF ID-11Materials Science Beamline was used.Pressed-powder wasplaced between the X-ray source(λ=0.26102˚A)and the detector on a graphitesample-holder,which was adjusted so that the beam hit the centre of the sample(0.2mm×0.2mm).The diffracted photons,within a15◦2θcone,obtained bytransmission,were collected with a Frelon CCD camera.Initiating current was fed through the wire a few seconds before startingthe XRD acquisition.The experiment was conducted in air atmosphere.Moredetails of the experiment are found in[11].Exposure time per frame was35ms and the total readout data storage timewas30ms,rendering a total time resolution of65ms per frame.During eachexperiment600XRD frames were recorded successively by a workstation run-ning under LINUX with Spec[16]acting as software for control and dataacquisition.2.4.SEMPorous specimens were embedded in an epoxy resin under vacuum.Polishingwas made on a lapping disk with diamond paste up to a degree of1␮m Thepolished surface was cleaned with isopropilic alcohol,dried and coated with goldby sputtering.Then,it was observed by SEM with a Zeiss DSM-950microscope(including EDS analysis).2.5.XRDProducts were ground and sieved below60␮m size for DRX.Powders weremixed with20%Si-NIST used as an internal standard.Recording of the datawas made in a Siemens Diffraktometer D5000(K Cu␣→λ=1.54056˚A)with a program to ensure quality of data.The range was from20to80◦at a step rateof0.03◦and an acquisition time of22s for each step.The diffractometer optic used to collect the samples was:aﬁxed aperture slit of2mm,one scattered-radiation slit of2mm after the sample,followed by a system of secondary Soller slits and the reception slit of0.2mm.After that secondary curved graphite monochromator is placed andﬁnally the detector slit of0.6mm.2.6.Data processingThe frames collected at the ESRF containing diffraction rings were integrated using scripts developed at ID11around the Fit2D program[17].Information of each frame was condensed into a standard format containing,2θ,intensity and statistical error for every step.Further treatment of the XRD patterns was made with a series of scripts written in IDL[18]toﬁt diffraction peaks to Gaus-sian curves.Transform[19]was used to map the diffraction pattern sequence. Rietveld analysis was made using Fullprof Suite[20].3.Results and discussion3.1.Post-synthesis studyHere,the obtained results from the reactions made at the laboratory will be brieﬂy described.3.1.1.TiCAs expected,Rietveld analysis shows that mostly TiC is present,together with some unreacted elemental titanium and graphite.Table2shows the phase percentages obtained for all the reactions.Fig.2(a)shows the adjusted diffractogram with phases indicated by Bragg peaks’positions.3.1.2.4TiC:1WCIt can be seen in Table2,that a67%of solid solution with formula Ti0.8W0.2C(correlating well with phase equilibrium diagram prediction)is detected.There is also presence of tita-nium carbide without tungsten(18%)and ca.12%of unreacted mixture and WC.3.1.3.3TiC:1WCAlthough there is still a majority of solid solution(with approximate formula Ti0.75W0.25C),very little impurities have been detected(WC and W2C)and there is no titanium carbide without solid solution,but there is little presence of unreacted titanium,tungsten and graphite.SEM study(Fig.3(a))conﬁrms the data by showing the presence of two main zones:a majori-tarian darker one,which corresponds to the solid solution,and a lighter one which corresponds particularly to the unreacted mixture(ca.18%of product).Table2Phase percentages obtained for each of the reactionsTiC4TiC:lWC3TiC:lWC2TiC:lWC1TiC:1WC %(Ti,W)C67.0078.6352.7625.92%TiC78.6017.97%WC 2.71 3.3612.3339.91%W2C0.69 2.9214.41%W 4.00 5.5711.91 4.03%C11.42 3.39 2.39 3.80 4.87%Ti9.98 4.009.3613.2810.86230M.J.Mas-Guindal et al./Journal of Alloys and Compounds419(2006)227–233Fig.2.Selected adjusted diffractograms for reaction products;dotted line corre-sponds to observed data and continuous line to calculated data;Bragg positions are indicated with vertical lines under each peak and it is also shown the differ-ence curve.(a)Diffractogram of TiC obtention(R p=24.2,R wp=31.2,R e=4.73,χ2=43.4);(b)diffractogram of reaction(III)(R p=13.8,R wp=17.5,R e=4.05,χ2=18.7);(c)diffractogram of reaction(IV)(R p=l3.5,R wp=17.0,R e=15.2,χ2=1.3).3.1.4.2TiC:1WCThe solid solution percentage appears decreased to a52% of the total product;its formula is Ti0.67W0.33C.An increase on the amount of unreacted mixture to a30%level is observed and up to11%of WC is found;Fig.2(b)shows thediffrac-Fig.3.SEM Micrographs of different reactions:(a)reaction(II),(b)reaction (IV),(c)reaction(IV).Zoom on the light phase showing the micrometrical spheres.togram with Bragg-peaks’positions and Rietveld reﬁnement. SEM-microstructure is similar as that of previous reaction but with an increase in the lighter zone percentage,corresponding to the unreacted mixture.M.J.Mas-Guindal et al./Journal of Alloys and Compounds 419(2006)227–233231Table 3Cell parameters and solid solution degree Composition S.S.degree a =b =c TiCTiC4.32804TiC:1WC Ti 0.8W 0.2C 4.32603TiC:1WC Ti 0.75W 0.25C 4.32472TiC:1WC Ti 0.65W 0.35C 4.32351TiC:1WCTi 0.60W 0.40C4.32273.1.5.TiC:WCThe most abundant phase corresponds now to WC (40%)and solid solution percentage has decreased to 26%;its formula is Ti 0.55W 0.45C which corresponds to saturation of the solid solu-tion.It is clearly seen an increase in the amount of W 2C to a 14%and the unreacted mixture percentage is a 20%.Fig.2(c)shows the diffractogram.Micrograph in Fig.3(b)shows the existence of a mostly light phase corresponding to WC and a darker one,which is the remainder.A zoom on the light phase (Fig.3(c))shows that WC has a microstructure of little spheres of micro-metric size (ca.1.5␮m).3.1.6.DiscussionTable 3shows the unit cell parameters and the degree of solid solution found using the Rietveld method.Results are in good agreement with expected behaviour,i.e.the more tungsten enter-ing in solid solution within the titanium carbide cell,a reduction in the unit cell is observed.This can be explained by the atomicradii of atomic elements:tungsten radium is 1.41˚Aand tita-nium radium is 1.47˚A,and a substitution of titanium atoms by tungsten atoms will thus result in a decrease of the cell and a displacement of the peaks corresponding to solid solution to a higher angle in the difrractogram.A graphic representation of cell parameter versus solid solu-tion degree (Fig.4)shows that it ﬁts a linear model indicating that Vegard’s Law for solid solutions is being followed [21].The equation for this model is:Y =4.32805−1.29803×10−4X(IX)Fig.4.Representation of cell parameter vs.solid solution degree and result of linear ﬁtting of the dots.Y being the cell parameter and X the amount of tungsten in solid solution (takes values between 0and 0.45).This expression,then,can be used for predicting the approxi-mate solid solution degree found in any ﬁnal proportion between TiC and WC of this system.The presence of secondary phases and rests of reactants in the product pellets is noticeable.There are various explanations for this.Mainly,it is due to the lack of equilibrium during the reaction:rapid heating and cooling of the sample makes it difﬁ-cult to reach the equilibrium;as reactions happen at high speed and intermediate species,like W 2C (which should not be stable below 1300◦C [22,23]),don’t evolve to the desired products and remain intact.Due to the small size of the pellets,which implies a bigger percentage of powder exposed to the atmosphere,there is an increase in non-desired products,specially at the surface of pellets.This is the case of the tungsten oxide that appears in the reaction at the synchrotron.A secondary effect of the lack of equilibrium is that reacting agents do not react completely;therefore,they appear in the ﬁnal product.3.2.Real-time study3.2.1.Synchrotron resultsFig.5shows diffractograms of reaction (I)obtained at the laboratory and the synchrotron.Data have been converted to d −1(nm −1)for ease of comparison.The ﬁrst impression shows that the synchrotron product is far cleaner from impurities and non-reacted parts than the laboratory obtained one;this happens not only because of the better precision that synchrotron radi-ation generates,but also from the fact that at the synchrotron measure is made on only one spot of the pellet,while for normal DRX,the product has suffered a milling and sieving process that introduces some impurities as a larger part of the pellet is used during the milling.Synchrotron peaks are assigned mainly to solid solution;nevertheless,solid solution and titanium car-bide have a similar pattern,and in the case of the synchrotron the lack of signiﬁcant peaks for WC or W 2C leads to supposi-tion that most of the tungsten is present in the solid solution,as expected for that composition.One can also observe the pres-ence of non-reacted graphite and a small peak at d −1=4.5,whichparative among the diffractogram of reaction 4:1made at laboratory (down)and at the synchrotron (up).232M.J.Mas-Guindal et al./Journal of Alloys and Compounds 419(2006)227–233Fig.6.Contour map of reaction;main peaks have labels identifying them.could correspond to non-reacted tungsten.Peak at d −1=2.6cor-responds to tungsten oxide,which appears only at the surface of the pellet because of the contact with air.3.3.Reaction mechanismFour main stages are seen:heating,transformation of ␣-titanium into ␤-titanium,reaction and cooling.Collected diffrac-tograms provide a map of the reaction;it is worth noting that reaction happens rapidly after the preheating of reactants.A con-tour bidimensional map of the reaction shows the evolution of the different phases during the process (Fig.6)and is helpful in visualising the mechanism,explained next.Selected diffrac-tograms of the depicted stages are found in Fig.7:-Initial situation at t =0s shows the peaks corresponding to ␣-titanium,tungsten and graphite.-At about 2.5s,the transformation of ␣-titanium (hexagonal-P63/mmc)into (␤-titanium (bcc-Fm3m)starts.At t =3.25,peak at d −1=4.3,corresponding to cubic titanium reaches the highest intensity and a moment later peaks decrease pre-sumably due to appearance of liquid titanium,but no evidence is shown.-Titanium (supposedly in liquid state)diffuses at ca.t =4.0s through the graphite and starts the reaction.The diffractogram at about 4.62s shows peaks corresponding to the conversion of the elements into the products;at that time,also the reac-tion of tungsten into solid solution can be observed,as tung-sten’s main peak at d −1=4.46disappears.At 6s,anincreaseFig.7.Diffractograms acquired with synchrotron radiation during reaction and representative of each stage:t =0s,raw products.t =2.5s,starting of transformation of ␣-titanium to ␤-titanium.t =3.25s,maximum intensity of ␤-titanium peak at d −1=4.3.t =4.62s,start of appearance of products.t =8.3s,reaction starts to cool.t =20.5s,principal phases already formed.t =24.5s,at the medium of cooling,product is already formed.Diffractogram corresponding to ﬁnal cooled product.M.J.Mas-Guindal et al./Journal of Alloys and Compounds419(2006)227–233233of some of the peaks corresponding to the products can be observed.-The process starts cooling at about8.3s from the initial moment.From now on no special additional features are observed.The main characteristic of this stage is the consol-idation of the solid solution phase with the growing of solid solution peaks and the solidiﬁcation of the molten substances. The presence of W2C is also detected,but at20s it trans-forms into product and does not appear in theﬁnal diffrac-togram.-At about14s,one observes the appearance of peaks corre-sponding to tungsten oxide,(mainly WO3);which,as already mentioned,is an effect that happens only at the surface of the pellet.-Cooling after this time does not add new noticeable reactions as can be seen at20.5s,24.5s and theﬁnal diffractogram.Summing up,reaction passes through the transformation of ␣-titanium into␤-titanium and then into liquid,so that it diffuses through the sample.Formation of products starts just after the melting of reactants(about5s after starting).4.Conclusions-A hard composite material made of a mixed carbide of titanium and tungsten has been obtained by means of a SHS reaction using as reagents the elemental forms.-The speed of the SHS reaction implies that no complete equi-librium state is achieved during reaction and secondary phases appear diminishing purity.-The Rietveld method has been used successfully to develop an expression which permits us to have a quite accurate mea-sure of the cell parameter of the solid solution formed in the mixed carbide;insertion of tungsten into the titanium carbide cell results in a linear evolution of the unit cell parametre, according to Vegard’s Law for solid solutions.Its expression is:Y=4.32805−1.29803×10−4Xfor X between0and0.45.Cell parameter decreases with the introduction of tungsten.-If more than45%of tungsten is present,two phases occur: saturated solid solution(Ti0.55W0.45C)and pure tungsten car-bide.-The percentage of solid solution formation decreases when there is more tungsten in the reaction and results in more amount of reactants in theﬁnal product.-Coexistence of phases starts to appear when going near the saturation of solid solution.The solid solution percentagedecreases markedly when entering the two-phase zone and an increase in tungsten carbide percentage is observed.-The reaction mechanism probably occurs through the dif-fusion of liquid titanium into the graphite and the tungsten forming titanium carbideﬁrst,and then entering tungsten into this formed carbide.AcknowledgmentsWe thank the ESRF for beamtime granted through experiment CH-1235.This work has been supported by the Spanish Science and Technology Agency(CICYT)under project No.MAT2004-04923-C02-01.References[1]A.G.Merzhanov,Ceram.Int.21(1995)371–379.[2]M.Pidria,E.Merlone,M.Rostagno,L.Tabone,F.Bechis,D.Vallauri,F.A.Deorsola,I.Amato,M.A.Rodr´ıguez,Mater.Sci.Forum432(2003)4374–4378.[3]A.G.Metcalfe,J.Ins.Met.73(1947)591–607.[4]S.Johnsson,Z.Metallkd.87(10)(1996)788.[5]A.Saidi,M.Barati,J.Mater.Prod.Tec.124(2002)166–170.[6]Z.A.Munir,U.Anselmi-Tamburini,Mater.Sci.Rep.3(7–8)(1989)277–365.[7]M.A.Rodr´ıguez,N.S.Makhonin,J.A.Escri˜n a,I.P.Borovinskaya,M.I.Osendi,M.F.Barba,J.E.Iglesias,J.S.Moya,Adv.Mater.7(8)(1995) 745–747.[8]J.S.Moya,J.E.Iglesias,F.J.Limpo,J.A.Escri˜n a,N.S.Makhonin,M.A.Rodr´ıguez,Acta Mater.45(8)(1997)3089–3094.[9]C.Curfs,I.G.Cano,G.B.M.Vaughan,X.Turrillas,˚A.Kvick,M.A.Rodr´ıguez,J.Eur.Ceram.Soc.22(2002)1039–1044.[10]L.Contreras,X.Turrillas,G.B.M.Vaughan,˚A.Kvick,M.A.Rodr´ıguez,Acta Mater.52(2004)4783–4790.[11]L.Contreras,X.Turrillas,M.J.Mas-Guindal,G.B.M.Vaughan,˚A.Kvick,M.A.Rodr´ıguez,J.Solid State Chem.178(2005)1595–1600.[12]C.R.Bowen,D.Derby,Br.Ceram.Trans.96(1)(1997)25.[13]HSC CHEMISTRY5.11©Outokumpu Research Oy,Pori,Finland,A.Roine /hsc.[14]H.M.Rietveld,J.Appl.Cryst.2(1969)65–71.[15]L.B.McCusker,R.B.V on Dreele,D.E.Cox,D.Lou¨e r,P.Scardi,J.Appl.Cryst.32(1999)36.[16]SPEC,Certiﬁed Scientiﬁc Software,P.O.BOX390640,Cambridge,MA02139.[17]A.Hammersley,S.O.Svensson,A.Thompson,Nucl.Instrum.MethodsA346(1994)312–321.[18]Research Systems Inc.(Kodak Company),Sterling,V A20164,USA.Program IDL Version5.2(1998).[19]Research Systems Inc.(Kodak Company),Sterling,V A20164,USA.Program NOeSYS.Version1.2(1998).[20]T.Roisnel,J.Rodr´ıguez-Carvajal,FullProf Suite(May2003)http://www.llb.cea.fr/fullweb/winplotr/winplotr.htm.[21]L.Vegard,Z.Phys.5(1921)17.[22]G.Jiang,W.Li,H.Zhuang,Mater.Sci.Eng.A354(2003)351–357.[23]G.Jiang,H.Zhuang,W.Li,Ceram.Int.30(2004)191–197.。

应力对xrd峰位置

X射线衍射（XRD）是一种常用的材料表征技术，可以用于确定材料的晶体结构和晶体缺陷等信息。

XRD峰的位置与材料的晶体结构和晶格常数有关，因此，应力对XRD峰位置有一定的影响。

在一定的应力范围内，当材料受到压缩应力时，晶格常数会缩小，导致XRD峰位置向较小的衍射角度偏移；而当材料受到拉张应力时，晶格常数会扩大，导致XRD峰位置向较大的衍射角度偏移。

这种应力对XRD峰位置的影响被称为“应力位移效应”。

需要注意的是，应力对XRD峰位置的影响程度与材料的晶体结构、应力状态等因素有关，因此，在进行XRD分析时，需要考虑这些因素的影响，以获得准确的结果。

此外，为了消除应力对XRD分析的影响，还需要进行应力校正等处理。

x射线衍射测量残余应力实验指导书

X射线衍射方法测量材料的残余应力一、实验目的与要求1.了解材料的制备过程及残余应力特点。

2.掌握X射线衍射（XRD）方法测量材料残余应力的实验原理和方法。

二、了解表面残余应力的概念、分类及测试方法种类, 掌握XRD仪器设备的操作过程。

三、实验基本原理和装置..1.X射线衍射测量残余应力原理当多晶材料中存在内应力时, 必然还存在内应变与之对应, 导致其内部结构(原子间相对位置)发生变化。

从而在X射线衍射谱线上有所反映, 通过分析这些衍射信息, 就可以实现内应力的测量。

材料中内应力分为三大类。

第I类应力, 应力的平衡范围为宏观尺寸, 一般是引起X射线谱线位移。

由于第I类内应力的作用与平衡范围较大, 属于远程内应力, 应力释放后必然要造成材料宏观尺寸的改变。

第II类内应力, 应力的平衡范围为晶粒尺寸, 一般是造成衍射谱线展宽。

第III类应力, 应力的平衡范围为单位晶胞, 一般导致衍射强度下降。

第II类及第III类内应力的作用与平衡范围较小, 属于短程内应力, 应力释放后不会造成材料宏观尺寸的改变。

在通常情况下, 我们测得是残余应力是指第一类残余应力。

当材料中存在单向拉应力时, 平行于应力方向的(hkl)晶面间距收缩减小(衍射角增大), 同时垂直于应力方向的同族晶面间距拉伸增大(衍射角减小), 其它方向的同族晶面间距及衍射角则处于中间。

当材料中存在压应力时, 其晶面间距及衍射角的变化与拉应力相反。

材料中宏观应力越大, 不同方位同族晶面间距或衍射角之差异就越明显, 这是测量宏观应力的理论基础。

原理见图1。

由于X射线穿透深度很浅, 对于传统材料一般为几十微米, 因此可以认为材料表面薄层处于平面应力状态, 法线方向的应力(σz )为零。

当然更适用于薄膜材料的残余应力测量。

图1 x 射线衍射原理图图2中φ及ψ为空间任意方向OP 的两个方位角, εφψ 为材料沿OP 方向的弹性应变, σx 及σy 分别为x 及y 方向正应力。

残余应力测量方法

残余应力是指材料内部或表面存在的不平衡力，它可以对材料的性能和可靠性产生重要影响。

以下是几种常见的残余应力测量方法：
1.X射线衍射法（X-ray Diffraction, XRD）：这是一种常用的非破坏性测量方法，通过测量
材料中晶体结构的畸变来间接计算残余应力。

X射线经过材料后会发生衍射，根据衍射角度的变化可以推断出残余应力的大小和方向。

2.中子衍射法（Neutron Diffraction）：类似于X射线衍射法，中子衍射法也是通过测量材
料晶体结构的畸变来确定残余应力。

相比X射线，中子具有更好的穿透能力，因此可以深入材料内部进行测量，适用于非金属材料的残余应力分析。

3.压电法（Piezoelectric Method）：利用材料的压电效应来测量残余应力。

该方法通过将
压电传感器固定在被测物体上，然后施加外力引起压电传感器的形变，根据形变量的变化推断出残余应力的大小。

4.高斯法（Hole Drilling Method）：这是一种常用的局部测量方法，适用于金属材料。

该
方法通过在被测物体上钻一个小孔，然后测量孔周围的表面应变的变化来计算残余应力。

5.激光干涉法（Laser Interferometry）：利用激光的干涉原理来测量表面的微小位移，从
而推断出残余应力的分布情况。

激光干涉法可以提供高精度的残余应力测量结果。

需要注意的是，不同的测量方法适用于不同类型的材料和应力状态，选择合适的方法取决于具体的应用需求和材料特性。

在进行残余应力测量时，应根据实际情况综合考虑各种因素，并采取适当的措施以确保测量结果的准确性和可靠性。

X射线荧光光谱法测定高铝耐火材料中氧化铝的测量不确定度评定

表# 测量结果一览表 % & ’ ( ) # * ) + ) , . / & + . 0 /, ) 1 2 ( + 1 O : " % ’ # 1 ( M K L F % ! （& ／ H J 4 0） ’ # 1 M " L ! ( # " F # ( F " ’ ( M # " ! M M L " M F K 1 " % F L ! " % 1 L M " ( F L F " L # F 1 " K % （） / . " , 0 N ，， % K " 1 ( !! % K " 1 M #M % K " 1 K %1 ，， ’ ! " % K #M ’ ! " % M (L ’ ! " % 1 K% ，， ’ ’ " ! F ’% ’ ’ " ! F K! ’ ’ " ! M (% ，， ’ # " ( 1 ## ’ # " 1 L %K ’ # " ( ! LL ，， ’ ( " 1 F M! ’ ( " M ’ !% ’ ( " M ! F% ，， ’ K " K K FF ’ K " K F %! ’ K " K K 1% ，， # ! " ! ! M! ’ F " F L (M # ! " ! ! MK ，， # ’ " # L M! # ’ " # M K% # ’ " 1 # #( ，， # # " M ( !’ # # " M L 1F # # " ( K ML ，， # ( " M K L% # ( " M 1 M( # ( " M 1 1’

原位XRD与中子衍射研究LiCoPO4磷酸钴锂

aged
new
battery type “18650”
2θ/°
In operando Neutron Diffraction
discharged
λ = 1.5484(2) Å
charged
?
10
2θ/°
150 10
2θ/°
150
graphite anode LiCoO2 cathode
Cu current collector Fe (bcc) housing
neutron absorption high
low
ANTARES (Senyshyn, Mühlbauer)
In operando Neutron Diffraction and Tomography
Δ=20µm
Capacity: Size: Voltage:
2600 mAh (Ø x L) 18.4 mm x 65 mm 3.7 V
LiMPO4 (M=Mn,Fe,Co,Ni) as Cathode Materials
Triphylite LiFePO4
(olivine structure)
Heterosite FePO4
U/V vs. Li/Li+
5.2
Ni3+/Ni2+
Co3+/Co2+ 4.8
4.4
4.0
Mn3+/Mn2+
Institute for Materials Science
Darmstadt
• Tight collaboration with the structural research group at the Institute for Materials Science (Darmstadt)

残余应力无损检测方法

残余应力无损检测方法嘿，你知道不？残余应力那可是个大问题呢！无损检测方法就像个超级侦探，能在不破坏材料的情况下找出残余应力。

那咱就说说这神奇的无损检测方法吧！首先，X 射线衍射法就超厉害。

把材料放在那，X 射线一照，就像医生给病人拍片子似的，能看出材料内部的残余应力分布。

步骤嘛，就是调整好设备，让X 射线准确地照射到材料上，然后分析反射回来的X 射线信号。

这多牛啊！注意事项呢，可得小心操作设备，别让X 射线伤着自己。

那安全性咋样？放心吧，只要按规定操作，那是妥妥的安全。

稳定性也没得说，每次检测结果都挺靠谱。

这种方法适合检测各种金属材料，优势就是准确、快速。

比如说在航空航天领域，那飞机零件的残余应力检测可离不开它。

检测得准，飞机飞得才安心嘛！再说说超声检测法。

这就像用超声波给材料做体检。

把探头放在材料上，超声波在材料里传播，通过分析超声波的变化就能知道残余应力的情况。

步骤简单，放好探头，启动设备就行。

注意别把探头弄坏了。

安全性那是杠杠的，超声波又不会伤人。

稳定性也不错，检测结果比较稳定。

这种方法应用场景可广了，汽车制造、机械加工都能用。

优势就是方便、快捷，可以在生产线上直接检测。

这不就像有个随时待命的小助手嘛！还有磁测法呢！就像用魔法探测材料的残余应力。

通过测量材料的磁性变化来判断残余应力。

步骤不难，把仪器靠近材料就行。

注意别让磁场干扰其他设备。

安全性好得很，没啥危险。

稳定性也还行。

在钢结构检测中很管用。

优势就是可以快速检测大面积的材料。

哇塞，这多厉害！总之，残余应力无损检测方法那是超级棒！各种方法都有自己的优势和应用场景。

在实际生产中，根据不同的需求选择合适的方法，就能让我们的产品更安全、更可靠。

这难道不是超赞的事情吗？咱可一定要重视残余应力检测，让我们的生活更美好！。

X射线应力测定方法.pdfDOC

X 射线应力测定技术预备知识一、X 射线的本质与产生1、X 射线的本质1895 年德国物理学家伦琴发现了 X 射线。

1912年德国物理学家劳埃等人成功地观察到 X 射线在晶体中的衍射现象，从而证实了 X 射线在本质上是一种电磁波。

依据电磁波的波长，从 3×10－4m 以上到10－13m 以下，可以把它们分别称为无线电波、红外线、可见光、紫外线、X 射线、γ射线和宇宙射线等（如图 1 所示）。

X 射线的波长范围在 10－12m ～ 10 － 8m 之间。

用于衍射分析的 X 射线波长通常在0.05nm ～0.25nm 范围，用于金属材料透视的 X 射线波长为 0.1nm ～0.005 nm ，甚至更短。

实验证明，波长越长的电磁波，其波动性越明显，波长越短的电磁波，其粒子性越明显。

X 射线和可见光、紫外线同其它基本粒子一样都同时具有波动性和粒子性二重特性。

正因为它们的具有波动性，光的干涉衍射现象才得以圆满解释；也正因为它们的粒子性，探测器才可以接收到一个个不连续的图1、电磁波谱光量子。

反映波动性的波长λ、频率υ与反映粒子性各个区域的上下限难以明确指定，本图中各种电磁波的边界是臆定的的光子能量ε之间存在以下关系： ε＝h υ＝hc/λ 式中 h 为普朗克常数，h ＝6.626×10－34J ·s ；c 为光速，也是 X 射线的传播速度，c ＝2.2998 ×108m/s 。

2、X 射线的产生研究证明，当高速运动的电子束（即阴极射线）与物体碰撞时，他们的运动便急遽的被阻止，从而失去所具有的动能，其中一小部分能量变成 X 射线的能量，发生 X 射线，而大部分能量转变成热能，使物体温度升高。

从原则上讲，所有基本粒子（电子、中子、质子等）其能量状态发生变化时，均伴随有 X 射线辐射。

通常使用的 X 射线都是从特制的 X 射线管中产生的。

图 2 是 X 射线管的结构和产生 X 射线示意图。

利用同步辐射X射线吸收光谱技术表征Ziegler-Natta催化剂活性位点的研究进展

2022 年第51 卷第 3 期石油化工PETROCHEMICAL TECHNOLOGY·357·利用同步辐射X 射线吸收光谱技术表征Ziegler-Natta 催化剂活性位点的研究进展谢吉嘉，刘月祥（中国石化北京化工研究院，北京 100013）［摘要］Ziegler-Natta 催化剂是聚烯烃生产的核心，但在原子层面对催化剂结构和聚合机理的认识仍不够清晰。

同步辐射X 射线吸收光谱（XAFS ）技术可有效观测催化剂活性中心原子临近壳层的化学结构，辅助探究聚合机理。

综述了利用XAFS 技术对Ziegler-Natta 催化剂进行表征的研究进展，重点关注催化剂各组分对活性中心结构的影响，并对聚合机理的研究进行总结。

［关键词］Ziegler-Natta 催化剂；活性中心；同步辐射；X 射线吸收光谱；烯烃聚合［文章编号］1000-8144（2022）03-0357-06 ［中图分类号］TQ 426.94 ［文献标志码］AThe active sites characterization of Ziegler -Natta catalysts by synchrotron X -ray absorption spectroscopy ：A reviewXie Jijia ，Liu Yuexiang（Sinopec Beijing Research Institute of Chemical Industry ，Beijing 100013，China ）［Abstract ］Ziegler-Natta catalyst is the core of polyoleﬁns production ，but the investigation of its chemical structure and polymerization mechanisms at atomic level is still needed to be further improved. Synchrotron X-ray absorption spectroscopy(XAFS) is a technology to evaluate the chemical structures of the neighbor shells of active atoms and can assist the understanding of polymerization mechanisms more in depth. This manuscript reviews the ﬁndings by the characterizations of Ziegler-Natta catalysts via XAFS and mainly focuses on the interactions between different compounds of the catalysts.［Keywords ］Ziegler-Natta catalysts ；active sites ；synchrotron ；X-ray adsorption spectroscopy ；oleﬁn polymerization进展与述评DOI ：10.3969/j.issn.1000-8144.2022.03.017［收稿日期］2021-09-02；［修改稿日期］2021-11-19。

同步辐射近边结构x射线吸收光谱

同步辐射近边结构x射线吸收光谱
同步辐射近边结构x射线吸收光谱（X-ray absorption near-edge structure, XANES）是一种分析材料的方法，通过测量材料中
在X射线辐射下的光吸收行为来研究其近边（较低能量区域）结构。

XANES是一种核心电子光谱技术，主要用于研究材料中的化
学成分、电荷分布以及近边电子结构，具有高分辨和高灵敏度的特点。

它可以提供关于材料的局部电子结构信息，例如价态、配位环境以及化学键性质等。

XANES的实验技术一般采用光源产生的连续能量的X射线，
通过材料的吸收辐射相互作用，测量材料的光吸收谱。

根据辐射能量的变化，可以获得材料的吸收边界域的信息。

通过与标准样品的对比，可以进行定量分析和结构解释。

这种技术在材料科学、能源储存、催化剂研究等领域有广泛应用。

特别是在催化剂研究中，XANES可以用于研究催化剂在
催化反应过程中的原子尺度的变化，了解催化剂的变化机制和活性位点的形成。

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(J. Soc. Mat. Sci., Japan), Vol.49, No.7, pp. 729-734, July 2000˜_•¶

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X-Ray Stress Measurement of Composite Material Using Synchrotron Radiation by Shigeki TAKAGO*, Toshihiko SASAKI**, Koichi AKITA***, Yasuo YOSHIOKA**** and Yukio HIROSE**

We used X-ray diffraction method using Synchrotron radiation (SR) for solving residual stress in composite mate-rial. Diffraction planes with arbitrary diffraction angle were measured. Moreover, there is a characteristic that the dif-ferent diffraction planes at same 2ƒÆ angle were obtained using SR with different wave length. In this study, effects of penetration depth on an X-ray parameter of the composite material were examined. First of all, the X-ray elastic con-stant of the single-phase body (PXEC) was measured for the evaluation of the phase stress. Next, the elastic defor-mation behavior of phase stress in the matrix phase was evaluated, and the influence of the second phase particle was investigated. Residual phase stress of each phase in the fracture surface is measured as an application example for the X-ray Fractography. The relation between the stress intensity factor and TiN volume fraction was examined.Trying to fracture toughness test in composite material, we discussed influence of fracture toughness value on resid-ual stress. Deformation behavior of softer matrix phase was controlled by hard second phase particle under macro-scopic tensile stress. It was found that residual stresses in the fracture surface were relaxed on the surface.Furthermore, there is the correlation between the stress intensity factor at the fracture and the phase stress in the matrix phase.Key words: Synchrotron radiation, X-ray stress measurement, Composite material, Micromechanics, Residual stress, Experimental stress analysis, X-ray fractography, Phase stress

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•õ Œ´•eŽó—• •½•¬11”N10ŒŽ12“ú Received Oct. 12, 1999•– Šw•¶‰ïˆõ ‹à‘ò‘åŠw‘åŠw‰@ •§920-1192 ‹à‘òŽsŠpŠÔ’¬, Graduate Student, Kanazawa Univ., Kakuma-machi, Kanazawa, 920-1192•–•– •³‰ïˆõ ‹à‘ò‘åŠwŽ©‘R‰ÈŠwŒ¤‹†‰È •§920-1192 ‹à‘òŽsŠpŠÔ’¬, Dept. of Mat. Sci. & Eng., Kanazawa Univ., Kakuma-machi, Kanazawa, 920-1192•–•–•– •³‰ïˆõ “Œ‹ž“s—§‘åŠw•HŠwŒ¤‹†‰È‹@ŠB•HŠw•ê•U •§192-0397 ”ª‰¤ŽqŽs“ì‘å‘ò, Dept. of Mech. Eng., Tokyo Metropolitan UniMinamiohsawa, Hachiouji, 192-0397•–•–•–•– •³‰ïˆõ ••‘ •H‹Æ‘åŠw•HŠw•”ƒGƒlƒ‹ƒM•[Šî‘b•HŠw‰È •§158-8557 “Œ‹ž“s•¢“c’J‹æ‹Ê’ç, Dept. of Energy Sci. and Eng., Musashi Inst. of

Tech., Setagaya-ku, Tokyo, 158-8557