704Y.Y.Zhuetal./Surface&CoatingsTechnology235(2013)699–705
Fig.9.SEMimagesofthewornsurfaceof(a)toplayer;(b)layerIII;(c)layersIandII;(d)substrate.
Fig.9(a),however,showsthewornsurfacehavingafewslightscratches.ThisphenomenonisobviousforthesparsecrystallinephaseembeddedintheamorphoussubstrateasshowninFig.4(d).ThewornsurfaceoflayerIIIshowsdiscontinuousshallowgrooves(seeFig.9(b)).Accordingtothemagni?cationoftherectanglemarkedinFig.9(b),thegroovesarenotdeepandsharp,NbCparticlesremainadherenttothematrix,protrudingfromthesurface.PartiallossesofthematrixcanbeobservedinregionAinFig.9(b).AccordingtoCola?oandVilar[34,35],ifthehardnessofthecounterbodyislowerthanthatofreinforcementparticles,thematrixwillbedamagedpreferentially.Intheweartest,thehardnessofthecounterbody(≈1500HV)issmallerthanthehardnessoftheNbCparticles(≈3000HV).IncanbeinferredthattheNbCparticleswithharderhardnesscanresisttomoremasslossesinthecompositematerials.Therefore,thebettermechanicalpropertyoflayerIIIisaresultoftheamorphousmatrixembeddedbyNbCparticles,whichcouldreinforcethehardnessandwearperfor-manceofthecoating.ThewornsurfacemorphologiesoflayersIandIIinFig.9(c)showmanycratersandsharpgrooves.Themagni?cationofthemarkedregionshowsthemorphologyofacrater.TheEPMAre-sultofthecratershowsthatitismainlycomposedofFeandCo.Itcanbeinferredthatthewearmasslossismainlycausedbyplasticdeforma-tionfollowedbymaterialdislodgementandformationofthecrater.Thesharpabrasivegroovestakeplacebymicrocutting,mostlikelybecauseofdetachmentoffewNbCparticlesandthehardasperitiesonthesur-faceofthealuminadisk.Fig.9(d)showstheSEMimageofthewornsurfaceofthesubstrate.ThedepthandwidthofgroovesinFig.9(d)aremorethanthoseinFig.9(c),whichcanbeindicativeofpoorwearresistanceofthesubstrate.
mainmechanismsaffectingthesetransitionsduringsolidi?cation.LayerIIIofthecoatingdisplaysexcellentmicrohardnessandwearresistanceduetotheamorphousmatrixembeddedbyNbCparticles.Acknowledgments
Theauthorswouldliketothankthe?nancialsupportprovidedbytheNationalNaturalScienceFoundationofChina(No.50971091)andtheMinistryoftheScienceandTechnologyofthePeople'sRepublicofChina(No.2009DFB50350).References
[1]J.J.Gilman,Science208(1980)856–861.
[2]A.Inoue,T.Zhang,H.Koshiba,A.Makino,J.Appl.Phys.83(1998)6362–6364.
[3]D.S.Song,J.H.Kim,E.Fleurg,W.T.Kim,D.H.Kim,J.Alloys,Compounds389(2005)
159–164.
[4]R.Vilar,O.Conde,S.Franco,Intermetallics7(1999)1227–1233.
[5]E.Toyserkani,A.Khajepour,S.Corbin,Lasercladding,CRCPressLLC,Florida,2005.[6]A.Kobayashi,S.Yano,H.Kimura,A.Inoue,Mater.Sci.Eng.B148(2008)110–113.[7]J.B.Cheng,X.B.Liang,B.S.Xu,Y.X.Wu,J.Non-Cryst.Solids355(2009)1673–1678.[8]W.M.Steen,J.Mazumder,LaserMaterialProcessing,fourthed.SpringerLondonLtd,
UnitedKingdom,2010.
[9]X.Wu,B.Xu,Y.Hong,Mater.Lett.56(2002)838–841.[10]T.M.Yue,Y.P.Su,J.Mater.Sci.42(2007)6153–6160.
[11]T.M.Yue,Y.P.Su,H.O.Yang,Mater.Lett.61(2007)209–212.
[12]D.T.A.Matthews,V.Ocelik,J.Th.M.DeHosson,Mater.Sci.Eng.A471(2007)
155–164.
[13]V.K.Balla,A.Bandyopadhyay,Surf.Coat.Technol.205(2010)2661–2667.
[14]P.L.Zhang,H.Yan,C.W.Yao,Z.G.Li,Z.S.Yu,P.Q.Xu,Surf.Coat.Technol.206(2011)
1229–1236.
[15]R.F.Li,Z.G.Li,J.Huang,P.L.Zhang,Y.Y.Zhu,Appl.Surf.Sci.257(2011)3554–3557.[16]X.Y.Ye,M.X.Ma,W.J.Liu,L.Li,M.L.Zhong,Y.X.Liu,Q.W.Wu,Adv.Mater.Sci.Eng.
2011(2010)485942–485949.
[17]D.Carvalho,S.Cardoso,R.Vilar,ScriptaMater.37(1997)523–527.[18]G.Y.Liang,J.Y.Su,Mater.Sci.Eng.,A290(2000)207–212.
[19]F.Audebert,R.Cola?o,R.Vilar,H.Sirkin,ScriptaMater.48(2003)281–286.[20]R.Trivedi,N.Wang,ActaMater.60(2012)3140–3152.
[21]M.Zhang,Surf.Coat.Technol.(2012),http://dx.doi.org/10.1016/j.surfcoat.2012.04.058.[22]R.Vilar,E.C.Santos,P.N.Ferreira,N.Franco,R.C.daSilva,ActaMater.57(2009)
5292–5302.
[23]C.Bezen?on,J.-D.Wagnière,S.Mokadem,M.Konter,W.Kurz,Proceedingsofthe3rd
LANE2001,Erlangen,2001.
[24]C.Bezen?on,A.Schnell,W.Kurz,ScriptaMater.49(2003)705–709.
5.Conclusions
(Fe,Co)-basedamorphouscompositecoatingisformedsuccessfullybyonesteplasercladdingmethod.Thedistributionofthemicrostruc-tureandpropertiesofthecoatingisanalyzed.Themicrostructureoftheinterface(coating/substrate)exhibitstwokindsoftransitionswhichareCET(columnartoequiaxedtransition)andequiaxedtoamor-phoustransition.ChemicalcompositionandthermalgradientGarethe
Y.Y.Zhuetal./Surface&CoatingsTechnology235(2013)699–705
[25]M.F.Schneider,Lasercladding,(Ph.D.Thesis)UniversityofTwente,Enschede,
Netherlands,1998.
[26]U.deOliveira,V.Ocelík,J.Th.M.DeHosson,Surf.Coat.Technol.197(2005)127–136.[27]S.F.Zhou,X.Q.Dai,H.Z.Zheng,Opt.LaserTechnol.43(2011)613–621.
[28]Y.Y.Zhu,Z.G.Li,J.Huang,M.Li,R.F.Li,Y.X.Wu,Appl.Surf.Sci.261(2012)896–901.[29]W.B.Pearson,AHandbookofLatticeSpacingsandStructuresofMetalsandAlloys,
PergamonPress,NewYork,1958.
[30]M.G?umann,C.Bezen?on,P.Canalis,W.Kurz,ActaMater.49(2001)1051–1062.
705
[31]J.D.Hunt,Mater.Sci.Eng.65(1984)75–83.
[32]J.Lipton,W.Heinemann,W.Kurz,Arch.Eisenhüttenwes55(1984)
195–200.
[33]S.L.Cockcroft,M.Rappaz,A.Mitchell,J.Fernihough,A.J.Schmalz,Materials
forAdvancedPowerEngineering,PartII,KluwerAcademicPublishers,Netherlands,1994.
[34]M.G?umann,R.Trivedi,W.Kurz,Mater.Sci.Eng.A226–228(1997)763–769.[35]R.Cola?o,R.Vilar,Communication255(2003)643–650.