1001-1-Quality Control and Nondestructive Tests in

JournalofNondestructiveEvaluation,Vol.20,No.3,September2001(q2001)QualityControlandNondestructiveTestsinMetalMatrixCompositesY.D.Huang,*L.Froyen,andM.WeversReceivedFebruary21,2001;RevisedOctober10,2001Qualitycontrolduringfabricationandfailuremonitoringduringservicehavegainedimportanceinthefieldofmetalmatrixcompositesbecauseoftheirgrowinguses,especiallyforstructuralapplica-tions.Thisreviewaimstoprovideasurveyofqualitycontrolandnondestructivetestingrelevanttometalmatrixcomposites.Thefirstpartpresentsthedeterminationofthereinforcementparameterswhichplayaveryimportantroleincontrollingtheperformanceofmetalmatrixcomposites.Thesecondpartdescribesthemainrelevantnondestructivetechniquesusedtoidentifythedefectsproducedduringfabricationorinservice.Italsoshowsthatthevalidationofnondestructivetechniquesandtherelationshipbetweentheirresultsandcomponentperformanceshouldbeparticu-larlyemphasizedinfutureresearchworkonmetalmatrixcomposites.KEYWORDS:Metalmatrixcomposite;defects;nondestructivetest;ultrasonics;acousticemission;radiography;thermography;eddycurrent;lowfrequencyvibration;scanningacousticmicroscopy;noncontactingelectromag-neticacoustictransducers.I.INTRODUCTIONisreferredtovariouspublicationswhichdealwithmateri-alsscienceandmicro-mechanics.(1–6)Inthepastfewyears,MMCshavebecomerealisticMetalmatrixcomposites(MMCs)offeranumberofpropertyadvantagesoverconventionalmetalmaterialscandidatesforengineeringcomponents,suchasautomo-tivedriveshafts,highspeedtrainbrakerotorsandaero-andalloys.Inthesecompositesoneconstituentisametaloralloyformingatleastonepercolatingnetwork.Theenginecomponents.Qualitycontrolduringtheirfabrica-tionroutesandfailuremonitoringduringtheirserviceareotherconstituentisembeddedinthismetalmatrixandusuallyservesasreinforcement,whichisnormallyathereforerecognizedasveryimportant.(7,8)ThisreviewsurveysthemethodstodeterminethereinforcementceramicsuchasSiCandAl2O3.TheirpropertiescanbetailoredbyvaryingtheconstituentsandtheirvolumeparametersthatplayaveryimportantroleincontrollingtheperformanceofMMCsandthenondestructivetestfractions.MMCsmaybeclassifiedintofourtypesaccordingtothetypeofreinforcement:MMCsreinforced(NDT)methodswhichareusedtodetectthedefectsormonitorthedefectevolutioninMMCs.withparticles(PRM),MMCsreinforcedwithwhiskersorshortfibers(SFRM),MMCsreinforcedwithcontinuousfibers(CFRM)andMMCsreinforcedwithmono-fila-ments(MFRM).FormoreinformationaboutMMCsone2.DETERMINATIONOFREINFORCEMENTPARAMETERS*Correspondingauthor.E-mail:[e-mail];Fax:[phone].MethodstodeterminethereinforcementparametersDepartmentMetaalkundeenToegepasteMateriaalkunde(MTM),arewellreviewedintheliterature.(5)InordertopresentKatholiekeUniversiteitLeuven,KasteelparkArenberg44,B-3001Hev-erlee,Belgium.thisinformationascompleteaspossible,themethods1130195-9298/01/0900-0113/0q2001PlenumPublishingCorporation114Huang,Froyen,andWeverscollectedinRef.(5)arealsoincludedinthepresentcanberelatedtoitsshape.D.JuulJensenusedthismethodtodeterminetheorientationdistributionofSiCreview,butonlyshortlydescribed.Severalnewlydevel-opedandinterestingmethodsarepresentedinmuchwhiskersinAlmatrix.(10)However,thismethodisnotappropriateforpoorlyalignedsystemswithoutauniquemoredetail.crystaldirection.2.1.AspectRatioTheaspectratioplaysaveryimportantroleincon-2.3.ReinforcementDistributiontrollingtheperformanceofMMCs,especiallythosecon-MostresearchinthefieldofMMCsisfocusedontainingshortfibersorwhiskers.Foralmostequiaxedthedevelopmentofmethodstocharacterizetheparticleparticles,theaspectratiocanbemeasuredonpolisheddistribution.Particleclusteringcanbecausedbyinsuffi-sections.Forshortfibersorwhiskers,thesimplestmethodcientmixing,sedimentationorslowsolidificationrates.ofmeasurementisthatdescribedbyArsenault.(9)TheTheconstraintsexertedbytheelasticceramicparticlesreinforcementisbroughtintosuspensionbydissolvingonthematrixalterthestressfieldinthevicinityofathematrixusingasuitableacid.Thisisfollowedbyclusterandgiverisetolocaltriaxialstresseswhicharesedimentationontoaglassorametallicsubstrateuponmuchhigherthantheremotestressappliedtothecompos-whichthefiberscanbeobservedeasilyunderascanningite.(16)Asaresult,clusterscanactascrackordecohesionelectronorlightopticalmicroscope.Analysiscanthennucleationsitesorbothatremotestresseswhicharelowerbedoneeithermanuallyorbyquantitativeimageanalysis.thanthematrixyieldstressandwhichcausetheMMCstofailatunpredictablelowstresslevels.Toimprove2.2.ReinforcementOrientationtheparticledistributioninMMCs,reliablemethodsforidentifyingandquantifyingsuchadistributionareveryPropertiesofMMCslargelydependonthereinforce-necessary.mentalignment.AwellalignedstructureisgenerallyAnumberofquantificationmethodshavebeenanisotropicinproperties(mechanicalorelectrical),developed,includingtheDirichlettessellationmethod,(17)whereasarandomlyorientedstructureismoreisotropic.theaverageinterparticlespacingormeanfreepath,(18)Forpotentialcommercialuse,amicrostructurewithshortthenearestandnearneighbordistances,(19)thelocalareafiberorwhiskerwellalignedwiththemainstress