Chemical and microstructural characterization of (Y or Zr)-doped CrAlN coatings

1 Chemical and mic os uc u al cha ac e iza ion o (Y o Z )-doped C AlN coa ings T.C. Rojasa, S. El M abe a, S. Domínguez-Meis e a, M. B izuelab, A. Ga cía-Luisb, J.C. Sánchez-Lópeza aIns i u o de Ciencia de Ma e iales de Se illa (CSIC-Uni . Se illa), A da. Amé ico Vespucio 49, 41092-Se illa, Spain bTECNALIA, Mikele egui Pasealekua, 2 20009 Donos ia-San Sebas ián, Spain Abs ac Magne on spu e ed ch omium aluminium ni ide ilms a e excellen candida es o ad anced machining and p o ec ion o high empe a u e applica ions. In his wo k C AlN- based coa ings including Y o Z as dopan s (2 a . %) a e deposi ed by d.c. eac i e magne on spu e ing on silicon subs a es using me allic a ge s and A /N2 mix u es. The ha dness p ope ies a e ound in he ange o 22-33 GPa wi h H/E a ios close o 0.1. The in luence o he dopan elemen in e ms o oxida ion esis ance a e hea ing in ai a 1000ºC is s udied by means o X- ay di ac ion (XRD), c oss-sec ional scanning elec on mic oscopy (X-SEM) and ene gy dispe si e X- ay analysis (EDAX). The mic os uc u e and chemical bonding a e in es iga ed using a ansmission elec on mic oscope (TEM) and elec on ene gy-loss spec oscopy (EELS) espec i ely. The imp o emen in oxida ion esis ance as compa ed o pu e C N coa ing is mani es ed in he o ma ion o a Al- ich ou e laye ha p o ec s he unde nea h coa ing om oxygen di usion. The bes pe o mance ob ained wi h he C AlYN ilm is in es iga ed by in si u annealing o his sample inside he TEM in o de o gain knowledge abou he s uc u al and chemical ans o ma ions induced du ing hea ing. *Manusc ip wi h changes highligh ed Click he e o iew linked Re e ences 2 1. In oduc ion C 1-xAlxN ilms deposi ed by physical apou deposi ion ha e p o en o be e ec i e p o ec i e coa ings o machining applica ions and a e p omising candida es o a ious o he high empe a u e applica ions [1-7]. The inco po a ion o Al o C N esul s in highe ha dness, he mal and chemical s abili y, allowing inc eased e iciency o cu ing and o ming ools [8,9]. The concen a ion o Al inside he coa ing is ied o be con olled below 70 mol % in o de o o m he me as able solid solu ion o Al inside he cc C N la ice [10,11]. The o ma ion o hexagonal AlN s uc u e usually exhibi s lowe ha dness and elas ic moduli, which esul s in lowe wea esis ance. When exposed o ai a ele a ed empe a u es, C 1- xAlxN ilms o m dense and adhe en mixed aluminium and ch omium oxide scales [1,8,12], which e en ually supp ess he oxygen di usion in o he bulk, p o iding excellen oxida ion esis ance up o empe a u es as high as 900ºC [13-15]. Cu en in es iga ions seek o imp o e he he mal and oxida ion esis ance abo e his limi empe a u e by inco po a ion o la ge (subs i u ional) a oms, as hey e ec i ely e a d di usion ela ed p ocesses ( eco e y, decomposi ion and ec ys alliza ion). Y ium has been p oposed o be e ec i e o his pu pose by seg ega ion o he oxide scale g ain bounda ies, blocking as di usion pa hs and inc easing he onse o decomposi ion o 1100ºC [16-20]. Mo eo e , he addi ion o a eac i e elemen was sugges ed o educe he accumula ion o oids a he subs a e/scale in e ace [21] o o imp o e he mechanical p ope ies o he scale by modi ying he oxide scale s uc u e [22]. In p e ious wo ks [4,5] we ha e shown he inc emen o he oxida ion esis ance o a C AlN coa ing abo e 800 °C. In iew o he bene icial e ec s o Y, he p esen wo k was unde aken o in es iga e he p ospec o adding Y o a simila C AlN coa ing o imp o e he oxida ion beha iou . Besides, in an a emp o es ablish some undamen al unde s anding on he oxida ion mechanism, ano he la ge subs i u ional a om like Z is inco po a ed ins ead o Y a simila concen a ion o check he in luence o he ype o dopan . 3 2. Expe imen al de ails C Al(Y,Z )N coa ings we e p epa ed on Si (100) subs a es by dc magne on spu e ing using A /N2 mix u es in a comme cial equipmen (CemeCon® CC800/8) p o ided wi h ou ec angula a ge s (200 mm  88 mm  5 mm): wo o ch omium (99.9% pu i y), one o aluminum (99.5% pu i y) and he las one ei he o y ium o zi conium (99.5% pu i y). The base p essu e o he acuum chambe was 110−4 Pa and he wo king p essu e se a 1 Pa, wi h a A /N2 a io o 1.5. The spu e ing condi ions we e se o 3000 W o he ch omium and aluminium and 1500 W o Y o Z a ge s. The sample holde was nega i ely biased in he ange o 110–120 V and he empe a u e anged om 200 o 400 °C due o plasma hea ing e ec . Chemical composi ion o he samples was ob ained by elec on p obe mic oanalysis (EPMA). The EPMA equipmen was a JEOL JXA-8200 Supe P obe ins umen equipped wi h ou wa eleng hs de ec o s (WDS) and one ene gy-dispe si e X- ay (EDX). The X- ay di ac ion pa e ns we e ob ained in a X´Pe P o PANALYTICAL di ac ome e in he con en ional  B agg-B en ano con igu a ion using Cu K adia ion. The mo phology and hickness o he coa ings was in es iga ed by scanning elec on mic oscopy (SEM) pe o med in a high esolu ion FEG mic oscope, HITACHI-4800. Samples g own on silicon subs a es we e clea ed o SEM c oss-sec ion examina ion. T ansmission elec on mic oscopy (TEM) and elec on ene gy-loss spec oscopy (EELS) we e ca ied ou in a Philips CM20 mic oscope ope a ing a 200 kV equipped wi h a PEELS spec ome e (Ga an). Fo he TEM obse a ion, c oss sec ional specimens we e p epa ed in he con en ional manne by mechanical polishing ollowed by A + ion milling o elec on anspa ency. The EELS da a we e acqui ed in he di ac ion mode wi h a came a leng h o 470 mm, a 2-mm spec ome e en ance ape u e and a collec ion angle o 1.45 m ad. These condi ions yielded an ene gy esolu ion a he ze o loss peak o 1.2 eV. A e he sub ac ion o he backg ound and he decon olu ion o plu al sca e ing, he spec a we e no malized o he jump. All o hese ea men s we e pe o med 4 wi hin he EL/P p og am (Ga an). The mechanical p ope ies we e measu ed wi h a Fische scope H100 dynamic mic op obe ins umen using a con en ional Vicke s inden e a loads up o 10 mN. The maximum load was selec ed in such a way ha he maximum inden a ion dep h did no exceed 10–15% o he coa ing hickness in o de o a oid he in luence o he subs a e. 3. Resul s and discussion 3.1. Chemical and mic os uc u al cha ac e iza ion Table 1 summa izes he chemical composi ion ob ained by EPMA and ha dness and Young’s modulus alues o he coa ings. The ha dness p ope ies a e ound in he ange o 22-33 GPa wi h H/E a ios close o 0.1. The mic oc ys alline s uc u e o he ou samples unde s udy is shown in he B agg-B en ano XRD scans o Fig. 1. I can be seen ha he C N- based coa ings exhibi he main peaks co esponding o C N calsbe gi e (JCPDS 01-076- 2494) al hough wi h di e en p e e ed o ien a ion and deg ee o c ys allini y depending on he sample. The inco po a ion o me als (Al and Y o Z ) in o he C N la ice esul s in b oade XRD peaks indica ing smalle c ys alline domains and change o ex u e. Thus, he C AlZ N coa ing is less ex u ed, mo e simila o C N, wi h <111> p e e ed o ien a ion. In he case o C AlN and C AlYN ilms, he p e e ed o ien a ions a e obse ed o shi o <220> and <200> espec i ely. Rep esen a i e c oss-sec ion SEM mic og aphs o he C N, C AlN, C AlZ N and C AlYN ilms a e shown in Fig. 2. The ilm hickness alues ypically a y in he 2–3 μm ange o he C AlN-based coa ings and 5.8 μm o C N. The exac alues a e included in he Table 1. A ypical columna s uc u e is obse ed al hough ce ain di e ences in column wid h and po osi y can be no iced. A mo e de ailed analysis by X-TEM allowed o de e mine he la e al size o he columns being es ima ed in 80 nm o he C AlN sample, 60-70 nm o C AlZ N and 100-110 nm o he C AlYN sample. These wid h alues co ela e wi h he measu ed 5 ha dness in he sense ha smalle columna sizes gene a e mo e compac s uc u es and acco dingly highe ha dness p ope ies. Fig 3 shows a con en ional b igh ield X-TEM image co esponding o he sample C AlYN as ep esen a i e example o he de eloped ilm mic os uc u e. F om his pic u e i is clea ly no iced ha besides o he ypical columna mic os uc u e along he g owing di ec ion a pe iodic laye ed s uc u e, pa allel o he subs a e, is obse ed. This laye ed a chi ec u e is o med by indi idual laye s o di e en hickness (20-30 nm he da ke laye and 4-8 nm he b igh e one). This pe iodic laye ed s uc u e appea s in he h ee C AlN-based samples and could be ela ed o he con igu a ion o he subs a es in espec o he magne on sou ces. Simila mul ilaye s uc u es ha e been obse ed in ilms p epa ed by magne on spu e ing due o he o a ion o he samples alongside he di e en a ge s [23,24]. The selec ed a ea elec on di ac ion (SAED) pa e n ob ained o his coa ing is including as inse in Fig. 3. The p esence o di ac ion ings is indica i e o he polyc ys alline na u e o he sample. The di ac ion ings can be assigned o he planes (111), (002) and (220) co esponding o he cubic phase o C (Al)N phase. Mo eo e , i is obse ed a ce ain p e e en ial o ien a ion o he c ys alli es o he (200) and (111) planes along he g owing di ec ion. In Fig. 4 a high- esolu ion ansmission elec on mic og aph ob ained om a c oss-sec ion image o he C AlYN sample is p esen ed. The measu ed d-spacing o he la ice inges is 2.4 Å ha can be assigned o he (111) plane o cubic C (Al)N phase. The dashed and do ed lines a e plo ed as eye-guide o indica e he sepa a ion be ween he columna and he mul ilaye s uc u e espec i ely. I is wo h o men ioning he s uc u al c ys alline cohe ency exis ing be ween he wo laye s wi h di e en con as abo emen ioned. The EELS analysis pe o med in he TEM p epa a ions o he coa ings is a powe ul ool o de e mine he chemical bonding s a e in nanos uc u ed and mul iphase sys ems [25]. The O-K, N-K and C -L2,3 spec a ha e been measu ed o all he C AlN-based samples and compa ed o C N [26], C 2N and c-AlN [27] e e ences compounds used as inge p in s. The hcp-AlN spec um is no conside ed as 6 he change o c ys al s uc u e o C 1-xAlxN om cubic o hexagonal appea s a x alues o 0.6-0.7 [10,11], much highe han hose shown by he coa ings unde s udy. The ine s uc u e o he N-K edge is known o be sensi i e o he local a omic en i onmen and consequen ly i can be used o iden i ica ion o he ch omium ni ides [26]. No O-K edge could be de ec ed in none o he samples in ag eemen wi h he low alues o oxygen measu ed by EPMA (< 1 a . %). Fig. 5 depic s he no malized N-K and C -L2,3 edges spec a o he all he samples and hose co esponding o he e e ence compounds. Some di e en ea u es can be highligh ed by compa ison o he spec a. The N-K edge o ch omium ni ides show wo main ea u es a abou 400 and 410 eV al hough hey di e in in ensi y. Thus, he second cha ac e is ic esonance peak is less p onounced o he C 2N in compa ison o he C N. The edge onse o he cubic o m o AlN appea s a highe ene gies, displaying he mos in ense ene gy-loss peak a ound 407 eV. The ELNES s uc u e o he N-K edge o he h ee C (Al)N-based coa ings is simila o he C N e e ence wi h he pa icula i ies o a diminu ion o he in ensi y o he i s peak and he de ec ion o a small shoulde a 407 eV. These di e ences can be a ibu ed o he Al inco po a ion in he C N phase and/o he o ma ion o AlN phases in he coa ings. Ne e heless, acco ding o he low Al con en and p e ious published wo ks he obse ed changes can be a he associa ed o he inco po a ion o Al inside he cubic C N la ice o ming me as able cubic C 1-xAlxN s uc u es [10,11,13]. The C -L2,3 edge spec a, ep esen ed in Fig 5 ( igh ), only di e in he ela i e in ensi y o he L2 and L3 esonances. The alues o he L3/L2 a ios (Δy) ha e been measu ed and he ob ained alues a e included o hei compa ison. The a e age alues a e ound a ound 1.25 close o a C N, con i ming he iden i ica ion o he C N as he ch omium ni ide phase o med in he C AlN-based coa ings. A u he de ailed in es iga ion is cu en ly unde going on his laye ed mic os uc u e in a FEG STEM mic oscope wi h EELS spec oscopy and HAADF de ec o wi h bigge la e al esolu ion o comple e he ilm cha ac e iza ion. 7 3.2. The mal and oxida ion esis ance In o de o s udy he oxida ion esis ance he samples ha e been annealed in ai a 1000ºC du ing 2h. SEM/EDX c oss-sec ion images o C N, C AlN, C AlZ N and C AlYN ilms a e his he mal ea men a e shown in Fig. 6. In he C N sample, he oxida ion has des oyed he o iginal columna mic os uc u e leading o a polyc ys alline mo phology whe e he c ys als on he su ace g ew la ge . On he con a y, he emaining samples s ill main ain he same columna mic os uc u e as-deposi ed and a op laye o di e en con as whose hickness depends on he sample (300 nm, 750 nm and 175 nm o pu e C AlN and Z - and Y- con aining samples espec i ely). The chemical composi ion o he ou e mos and inne laye s was analysed by EDX o in es iga e he in luence o he dopan Y o Z in he ilm oxida ion. I mus be men ioned ha simila analysis ca ied ou in he C N ilm (no shown) iden i ied only C and O signals, indica ing ully oxida ion. Fig. 7 shows he EDX spec a pe o med in he op laye s and inne egions oge he wi h an elemen al composi ion p o ile along he en i e hickness o he coa ings. As expec ed he op laye is o med by ch omium and aluminium oxides o med by ou wa d and inwa d di usion o hese me als and oxygen espec i ely. Howe e , i is clea ly in e ed ha oxygen p og essed u he in he C AlZ N coa ing, o ming a la ge oxides scale. Compa ing he EDX spec a shown in Figs. 7a and 7b, he ni ogen signal is compa a i ely much lowe in he C AlZ N sample indica ing ha oxida ion p ocess p og esses o a u he ex en . The in ensi y a io O/N measu ed om he EDX spec a was ound o be 0.9 (C AlZ N) and 0.4 (C AlYN) in ag eemen wi h p e ious esul s. A ending o he Z and Y signals i is obse ed a Z deple ion in he oxide laye while he Y con en emains almos cons an in he inne and ou e pa . The good oxida ion esis ance was also con i med by examining he coa ings by XRD a e hea ing up o 1000ºC. Fig. 8 depic s he XRD pa e ns whe e i can be seen he (111), (200) and (220) e lec ions o C (Al)N phase as p edominan componen besides incipien peaks om C 2O3 phase. No 8 signi ican di e ences in in ensi y a e obse ed depending on he ype o dopan (Z o Y) al hough i can be no iced ha he C 2O3 c ys alli es a e mo e andomly dis ibu ed in he case o C AlZ N han in he C AlYN ilm whe e he <120> a 41.6º is he p e e en ial o ien a ion. Aluminium oxides a e no de ec ed indica ing ha his elemen mus be p esen o ming mix u es wi h ch omium oxides o in amo phous s a e. This ac migh be an in luence o y ium elemen on he g ow h mechanism o he oxide scale ha yielded an imp o ed esis ance agains oxida ion. In summa y, hese esul s demons a e a be e p o ec ion agains oxida ion o C AlYN coa ing composi ion up o empe a u es o 1000ºC. Y ium a oms appea o di use ou concomi an ly wi h C and Al o ming a mo e e icien p o ec i e oxide laye whils Z a oms howe e seems o concen a e in he unal e ed ilm s uc u e. Wi h he aim o ob aining complemen a y in o ma ion on he chemical and mic os uc u al changes occu ing du ing hea ing an in si u annealing o he C AlYN sample was ca ied ou inside he TEM mic oscope. In Fig. 9a he EELS spec a (N-K and O-K edges) measu ed a di e en empe a u es a e shown. The O-K edge begins o appea a 1100ºC, below his empe a u e no oxygen signal is clea ly de ec ed. The N-K edge ine s uc u e becomes mo e de ined wi h he inc ease o he empe a u e, especially abo e 750ºC, indica i e o a be e c ys allised C AlN phase. The mos signi ican happened a 1100ºC when oxygen en e ed in o he ilm s uc u e. This change is ela ed o he decomposi ion o he ni ide by N2- emo al and oxygen inco po a ion as desc ibed in p e ious publica ions [1,14,17]. A ep esen a i e TEM image aken a 1000ºC, jus be o e he deg ada ion s a -up, (c . Fig. 9b) shows ha inside he coa ing he mic os uc u e emains almos unal e ed. The laye ed s uc u e is main ained bu wi h highe deg ee o he c ys allini y inside he C AlN phase as demons a ed by XRD. Conclusions 9 The he mal and oxida ion esis ance o C AlN-based coa ings doped wi h Z o Y ( 2 a .%) p epa ed by magne on spu e ing ha e been s udied compa a i ely. The p epa ed coa ings a e mainly cons i u ed by cubic C (Al)N phase and show a dense columna mic os uc u e ha esis ed he oxida ion in ai up o 1000ºC al hough ce ain di e ences in oxida ion a e a e no iced. Thus, he bene icial e ec o aluminium as p o ec i e agen o C N phases agains oxygen eac i i y is ein o ced in he case o y ium, educing he oxida ion a e and modi ying he oxide g ow h mechanism. The addi ion o his elemen p omo es he o ma ion o a dense mixed (C , Al)-oxide op laye ha a oids inwa d di usion o oxygen. Zi conium a oms did no di use oge he wi h C and Al and he oxida ion p og esses o a g ea e ex en . The mic os uc u al and chemical ans o ma ions induced du ing he mal ea men we e ollowed in si u by TEM/EELS analysis con i ming a high s abili y up o 1000ºC whe e he coa ing began o decompose and oxidize. Acknowledgmen s The au ho s a e g a e ul o he Spanish Minis y o Science and Inno a ion (p ojec s No. MAT2007-66881-C02-01, MAT2010-21597-C02-01 and Consolide FUNCOAT CSD2008- 00023), Jun a de Andalucía (TEP217) and I3P p og amme o CSIC o inancial suppo . 4 wi hin he EL/P p og am (Ga an). The mechanical p ope ies we e measu ed wi h a Fische scope H100 dynamic mic op obe ins umen using a con en ional Vicke s inden e a loads up o 10 mN. The maximum load was selec ed in such a way ha he maximum inden a ion dep h did no exceed 10–15% o he coa ing hickness in o de o a oid he in luence o he subs a e. 3. Resul s and discussion 3.1. Chemical and mic os uc u al cha ac e iza ion Table 1 summa izes he chemical composi ion ob ained by EPMA and ha dness and Young’s modulus alues o he coa ings. The ha dness p ope ies a e ound in he ange o 22-33 GPa wi h H/E a ios close o 0.1. The mic oc ys alline s uc u e o he ou samples unde s udy is shown in he B agg-B en ano XRD scans o Fig. 1. I can be seen ha he C N- based coa ings exhibi he main peaks co esponding o C N calsbe gi e (JCPDS 01-076- 2494) al hough wi h di e en p e e ed o ien a ion and deg ee o c ys allini y depending on he sample. The inco po a ion o me als (Al and Y o Z ) in o he C N la ice esul s in b oade XRD peaks indica ing smalle c ys alline domains and change o ex u e. Thus, he C AlZ N coa ing is less ex u ed, mo e simila o C N, wi h <111> p e e ed o ien a ion. In he case o C AlN and C AlYN ilms, he p e e ed o ien a ions a e obse ed o shi o <220> and <200> espec i ely. Rep esen a i e c oss-sec ion SEM mic og aphs o he C N, C AlN, C AlZ N and C AlYN ilms a e shown in Fig. 2. The ilm hickness alues ypically a y in he 2–3 μm ange o he C AlN-based coa ings and 5.8 μm o C N. The exac alues a e included in he Table 1. A ypical columna s uc u e is obse ed al hough ce ain di e ences in column wid h and po osi y can be no iced. A mo e de ailed analysis by X-TEM allowed o de e mine he la e al size o he columns being es ima ed in 80 nm o he C AlN sample, 60-70 nm o C AlZ N and 100-110 nm o he C AlYN sample. These wid h alues co ela e wi h he measu ed 5 ha dness in he sense ha smalle columna sizes gene a e mo e compac s uc u es and acco dingly highe ha dness p ope ies. Fig 3 shows a con en ional b igh ield X-TEM image co esponding o he sample C AlYN as ep esen a i e example o he de eloped ilm mic os uc u e. F om his pic u e i is clea ly no iced ha besides o he ypical columna mic os uc u e along he g owing di ec ion a pe iodic laye ed s uc u e, pa allel o he subs a e, is obse ed. This laye ed a chi ec u e is o med by indi idual laye s o di e en hickness (20-30 nm he da ke laye and 4-8 nm he b igh e one). This pe iodic laye ed s uc u e appea s in he h ee C AlN-based samples and could be ela ed o he con igu a ion o he subs a es in espec o he magne on sou ces. Simila mul ilaye s uc u es ha e been obse ed in ilms p epa ed by magne on spu e ing due o he o a ion o he samples alongside he di e en a ge s [23,24]. The selec ed a ea elec on di ac ion (SAED) pa e n ob ained o his coa ing is including as inse in Fig. 3. The p esence o di ac ion ings is indica i e o he polyc ys alline na u e o he sample. The di ac ion ings can be assigned o he planes (111), (002) and (220) co esponding o he cubic phase o C (Al)N phase. Mo eo e , i is obse ed a ce ain p e e en ial o ien a ion o he c ys alli es o he (200) and (111) planes along he g owing di ec ion. In Fig. 4 a high- esolu ion ansmission elec on mic og aph ob ained om a c oss-sec ion image o he C AlYN sample is p esen ed. The measu ed d-spacing o he la ice inges is 2.4 Å ha can be assigned o he (111) plane o cubic C (Al)N phase. The dashed and do ed lines a e plo ed as eye-guide o indica e he sepa a ion be ween he columna and he mul ilaye s uc u e espec i ely. I is wo h o men ioning he s uc u al c ys alline cohe ency exis ing be ween he wo laye s wi h di e en con as abo emen ioned. The EELS analysis pe o med in he TEM p epa a ions o he coa ings is a powe ul ool o de e mine he chemical bonding s a e in nanos uc u ed and mul iphase sys ems [25]. The O-K, N-K and C -L2,3 spec a ha e been measu ed o all he C AlN-based samples and compa ed o C N [26], C 2N and c-AlN [27] e e ences compounds used as inge p in s. The hcp-AlN spec um is no conside ed as 6 he change o c ys al s uc u e o C 1-xAlxN om cubic o hexagonal appea s a x alues o 0.6-0.7 [10,11], much highe han hose shown by he coa ings unde s udy. The ine s uc u e o he N-K edge is known o be sensi i e o he local a omic en i onmen and consequen ly i can be used o iden i ica ion o he ch omium ni ides [26]. No O-K edge could be de ec ed in none o he samples in ag eemen wi h he low alues o oxygen measu ed by EPMA (< 1 a . %). Fig. 5 depic s he no malized N-K and C -L2,3 edges spec a o he all he samples and hose co esponding o he e e ence compounds. Some di e en ea u es can be highligh ed by compa ison o he spec a. The N-K edge o ch omium ni ides show wo main ea u es a abou 400 and 410 eV al hough hey di e in in ensi y. Thus, he second cha ac e is ic esonance peak is less p onounced o he C 2N in compa ison o he C N. The edge onse o he cubic o m o AlN appea s a highe ene gies, displaying he mos in ense ene gy-loss peak a ound 407 eV. The ELNES s uc u e o he N-K edge o he h ee C (Al)N-based coa ings is simila o he C N e e ence wi h he pa icula i ies o a diminu ion o he in ensi y o he i s peak and he de ec ion o a small shoulde a 407 eV. These di e ences can be a ibu ed o he Al inco po a ion in he C N phase and/o he o ma ion o AlN phases in he coa ings. Ne e heless, acco ding o he low Al con en and p e ious published wo ks he obse ed changes can be a he associa ed o he inco po a ion o Al inside he cubic C N la ice o ming me as able cubic C 1-xAlxN s uc u es [10,11,13]. The C -L2,3 edge spec a, ep esen ed in Fig 5 ( igh ), only di e in he ela i e in ensi y o he L2 and L3 esonances. The alues o he L3/L2 a ios (Δy) ha e been measu ed and he ob ained alues a e included o hei compa ison. The a e age alues a e ound a ound 1.25 close o a C N, con i ming he iden i ica ion o he C N as he ch omium ni ide phase o med in he C AlN-based coa ings. A u he de ailed in es iga ion is cu en ly unde going on his laye ed mic os uc u e in a FEG STEM mic oscope wi h EELS spec oscopy and HAADF de ec o wi h bigge la e al esolu ion o comple e he ilm cha ac e iza ion. 7 3.2. The mal and oxida ion esis ance In o de o s udy he oxida ion esis ance he samples ha e been annealed in ai a 1000ºC du ing 2h. SEM/EDX c oss-sec ion images o C N, C AlN, C AlZ N and C AlYN ilms a e his he mal ea men a e shown in Fig. 6. In he C N sample, he oxida ion has des oyed he o iginal columna mic os uc u e leading o a polyc ys alline mo phology whe e he c ys als on he su ace g ew la ge . On he con a y, he emaining samples s ill main ain he same columna mic os uc u e as-deposi ed and a op laye o di e en con as whose hickness depends on he sample (300 nm, 750 nm and 175 nm o pu e C AlN and Z - and Y- con aining samples espec i ely). The chemical composi ion o he ou e mos and inne laye s was analysed by EDX o in es iga e he in luence o he dopan Y o Z in he ilm oxida ion. I mus be men ioned ha simila analysis ca ied ou in he C N ilm (no shown) iden i ied only C and O signals, indica ing ully oxida ion. Fig. 7 shows he EDX spec a pe o med in he op laye s and inne egions oge he wi h an elemen al composi ion p o ile along he en i e hickness o he coa ings. As expec ed he op laye is o med by ch omium and aluminium oxides o med by ou wa d and inwa d di usion o hese me als and oxygen espec i ely. Howe e , i is clea ly in e ed ha oxygen p og essed u he in he C AlZ N coa ing, o ming a la ge oxides scale. Compa ing he EDX spec a shown in Figs. 7a and 7b, he ni ogen signal is compa a i ely much lowe in he C AlZ N sample indica ing ha oxida ion p ocess p og esses o a u he ex en . The in ensi y a io O/N measu ed om he EDX spec a was ound o be 0.9 (C AlZ N) and 0.4 (C AlYN) in ag eemen wi h p e ious esul s. A ending o he Z and Y signals i is obse ed a Z deple ion in he oxide laye while he Y con en emains almos cons an in he inne and ou e pa . The good oxida ion esis ance was also con i med by examining he coa ings by XRD a e hea ing up o 1000ºC. Fig. 8 depic s he XRD pa e ns whe e i can be seen he (111), (200) and (220) e lec ions o C (Al)N phase as p edominan componen besides incipien peaks om C 2O3 phase. No 8 signi ican di e ences in in ensi y a e obse ed depending on he ype o dopan (Z o Y) al hough i can be no iced ha he C 2O3 c ys alli es a e mo e andomly dis ibu ed in he case o C AlZ N han in he C AlYN ilm whe e he <120> a 41.6º is he p e e en ial o ien a ion. Aluminium oxides a e no de ec ed indica ing ha his elemen mus be p esen o ming mix u es wi h ch omium oxides o in amo phous s a e. This ac migh be an in luence o y ium elemen on he g ow h mechanism o he oxide scale ha yielded an imp o ed esis ance agains oxida ion. In summa y, hese esul s demons a e a be e p o ec ion agains oxida ion o C AlYN coa ing composi ion up o empe a u es o 1000ºC. Y ium a oms appea o di use ou concomi an ly wi h C and Al o ming a mo e e icien p o ec i e oxide laye whils Z a oms howe e seems o concen a e in he unal e ed ilm s uc u e. Wi h he aim o ob aining complemen a y in o ma ion on he chemical and mic os uc u al changes occu ing du ing hea ing an in si u annealing o he C AlYN sample was ca ied ou inside he TEM mic oscope. In Fig. 9a he EELS spec a (N-K and O-K edges) measu ed a di e en empe a u es a e shown. The O-K edge begins o appea a 1100ºC, below his empe a u e no oxygen signal is clea ly de ec ed. The N-K edge ine s uc u e becomes mo e de ined wi h he inc ease o he empe a u e, especially abo e 750ºC, indica i e o a be e c ys allised C AlN phase. The mos signi ican happened a 1100ºC when oxygen en e ed in o he ilm s uc u e. This change is ela ed o he decomposi ion o he ni ide by N2- emo al and oxygen inco po a ion as desc ibed in p e ious publica ions [1,14,17]. A ep esen a i e TEM image aken a 1000ºC, jus be o e he deg ada ion s a -up, (c . Fig. 9b) shows ha inside he coa ing he mic os uc u e emains almos unal e ed. The laye ed s uc u e is main ained bu wi h highe deg ee o he c ys allini y inside he C AlN phase as demons a ed by XRD. Conclusions 9 The he mal and oxida ion esis ance o C AlN-based coa ings doped wi h Z o Y ( 2 a .%) p epa ed by magne on spu e ing ha e been s udied compa a i ely. The p epa ed coa ings a e mainly cons i u ed by cubic C (Al)N phase and show a dense columna mic os uc u e ha esis ed he oxida ion in ai up o 1000ºC al hough ce ain di e ences in oxida ion a e a e no iced. Thus, he bene icial e ec o aluminium as p o ec i e agen o C N phases agains oxygen eac i i y is ein o ced in he case o y ium, educing he oxida ion a e and modi ying he oxide g ow h mechanism. The addi ion o his elemen p omo es he o ma ion o a dense mixed (C , Al)-oxide op laye ha a oids inwa d di usion o oxygen. Zi conium a oms did no di use oge he wi h C and Al and he oxida ion p og esses o a g ea e ex en . The mic os uc u al and chemical ans o ma ions induced du ing he mal ea men we e ollowed in si u by TEM/EELS analysis con i ming a high s abili y up o 1000ºC whe e he coa ing began o decompose and oxidize. Acknowledgmen s The au ho s a e g a e ul o he Spanish Minis y o Science and Inno a ion (p ojec s No. MAT2007-66881-C02-01, MAT2010-21597-C02-01 and Consolide FUNCOAT CSD2008- 00023), Jun a de Andalucía (TEP217) and I3P p og amme o CSIC o inancial suppo . 10 Re e ences 1. O. Banakh, P. E. Schmid, R. Sanjinés, F. Lé y, Su . Coa . Technol. 163–164 (2003) 57. 2. M. Kawa e, A.K. Hashimo o, T. Suzuki, Su . Coa . Technol. 165 (2003)163. 3. A.E. Rei e , V.H. De linge , B. Hanselmann, T. Bachmann, B. Sa o y, Su . Coa . Technol. 7 (2005) 2114. 4. J.C. Sánchez-López, D. Ma ínez-Ma ínez, C. López-Ca es, A. Fe nández, M. B izuela, A. Ga cía-Luis, J.I. Oña e, J. Vac. Sci. Technol. A 23, 681-686 (2005). 5. M. B izuela, A. Ga cía, I. B ace as, J.I. Oña e, J.C. Sánchez-López, D. Ma ínez- Ma ínez, C. López-Ca es, A. Fe nández, Su . Coa . Technol. 200, 192-197 (2005). 6. H.C. Ba shilia, N. Sel akuma , B. Deep hi, K.S. Rajam, Su . Coa . Technol. 201 (2006) 2193. 7. J. Lin, B. Mish a, J.J. Moo e, W.D. Sp oul, Su . Coa . Technol. 201 (2006) 4329. 8. J.L. End ino, G.S. Fox-Rabino ich, A. Rei e , S.V. Veldhuis, R. Escoba Galindo, J.M. Albella, J.F. Ma co, Su . Coa . Technol. 201 (2007) 4505. 9. L. Wang, X. Nie, J. Housden, E. Spain, J.C. Jiang, E.I. Mele is, A. Leyland, A. Ma hews, Su . Coa . Technol. 203 (2008) 816. 10. H. Hasegawa, M. Kawa e, T. Suzuki, Su . Coa . Technol. 200 (2005) 2409. 11. P.H. May ho e , D. Music, Th. Reeswimkel, H.-G. Fuss, J.M. Schneide , Ac a Ma e . 56 (2008) 2469. 12. R. Escoba Galindo, J.L. End ino, R. Ma ínez, J.M. Albella, Spec ochimica Ac a Pa B 65 (2010) 950–958. 13. M. Kawa e, A. K. Hashimo o, T. Suzuki, Su . Coa . Technol. 165 (2003)163. 14. H. Willmann, P.H. May ho e , P.O.A. Pe sson, A. E. Rei e , L. Hul man, C. Mi e e , Sc ip a Ma e . 54 (2006) 1847. 15. H.C. Ba shilia, B. Deep hi, K.S. Rajam, K.P. Bha i, S. Chaudha y, J. Vac. Sci. Technol. A 27 (2009) 29. 16. F. Ro e e, P. H. May ho e , A. Reinhold , J. Maye , J.M. Schneide , Su . Coa . Technol. 202 (2008) 5870. 17. F. Ro e e, P. H. May ho e , J. Vac. Sci. Technol. A 26 (2008) 29. 18. K.-D. Bouzakis, N. Michailidis, S. Ge a dis, G. Ka i zoglou, E. Lili, M. Pappa, M. B izuela, A. Ga cia-Luis, R. C eme , Su . Coa . Technol. 203 (2008) 781. 19. F. Ro e e, D. Music, J. M. Schneide , P. H. May ho e , Ac a Ma e . 58 (2010) 2708. 11 20. R. B aun, F. Ro e e, P.H. May ho e , C. Leyens, In e me allics 18 (2010) 479. 21. D.P. Whi le, J. S inge , Philos. T ans. R. Soc. London Se . A-Ma h. Phys. Eng. Sci. 295 (1980) 309. 22. Y. Sai o, T. Ma uyama, T. Amano, Ma e . Sci. Eng. 87 (1987) 275. 23. M. Panjan, T. Pe e man, M. Cekada, P. Panjan, Su . Coa . Technol. 204 (2009) 850. 24. M. Panjan, S. S u n, P. Panjan, M. Cekada, Su . Coa . Technol. 203 (2008) 554. 25. D. Ma ínez-Ma ínez, C. López-Ca es, A. Jus o, A. Fe nández, J. C. Sánchez-López, A. Ga cía-Luis, M. B izuela, J. I. Oña e. J. Vac. Sci. Technol. A 23, 1732-1736 (2005). 26. C. Mi e baue , C. Hébe , G. Ko hlei ne , F. Ho e , P. Scha schneide , H.W. Zandbe gen, Solid S a e Comm. 130 (2004) 209. 27. M. Mackenzie, GC. Wea he ly, D.W. McComb, A.J. C a en, Sc ip a Ma e ialia 53 (2005) 983-987. 28. H. Hasegawa, K. Ohashi, S. Tsukamo o, T. Sa o, T. Suzuki, Su . Coa . Technol. 202 (2007) 786. 12 Figu e cap ions 1. XRD di ac og ams o he C Al(Y,Z )N coa ings unde s udy. A C N di ac ion pa e n is included o compa ison pu poses. 2. SEM c oss-sec ional iews o he C N, C AlN, C AlZ N and C AlYN coa ings. 3. X-TEM image ob ained om he C AlYN coa ing. The SAED pa e n is included as inse . 4. HRTEM image ob ained om a c oss-sec ion p epa a ion o he C AlYN coa ing. 5. N-K and C -L2,3 edges o he EELS spec a o all he C AlN-based samples and hose co esponding o he e e ence compounds (C N, C 2N and c-AlN). 6. X-SEM images aken a e oxida ion in ai a 1000ºC o he C N, C AlN, C AlZ N and C AlYN coa ings. 7. EDX analysis ca ied ou in he c oss sec ion p epa a ions o he C AlZ N and C AlYN samples a e hea ing a 1000`C. Spec a ob ained om he opmos laye and inne pa o he C AlZ N (le ) and C AlYN ( igh ) coa ings. Elemen al chemical composi ion p o ile ob ained ac oss he C AlZ N (le ) and C AlYN ( igh ) coa ings. 8. XRD di ac og ams o he C AlZ N and C AlYN coa ings a e oxida ion in ai a 1000º. ( symbols co espond o C N (JCPDS ca d# 01-076-2494) and  symbols co espond o C 2O3 peaks (JCPDS ca d# 01-076-0147). 9. a) E olu ion o he N-K and O-K edge EELS spec a o he C AlYN sample du ing annealing in acuum up o 1000ºC and b) TEM pic u e e ealing he mul ilaye ed s uc u e be o e o al decomposi ion p oduced a 1100ºC. Table 1. Chemical composi ion, hickness and mechanical p ope ies o he C (Al)N- based coa ings. C Al Y o Z N hickness H E Sample a .% (μm) (GPa) (GPa) C N 45.6 - - 54.4 5.8 27 265 C AlN 36.5 8.3 - 55.2 3.3 30 304 C AlYN 38.6 5.1 1.7 54.6 2.4 22 231 C AlZ N 38.8 4.5 2.0 54.8 2.8 33 317 Table(s) Figu e(s) Click he e o download high esolu ion image Figu e 7a Click he e o download high esolu ion image Figu e 7b Click he e o download high esolu ion image Figu e 7c Click he e o download high esolu ion image Figu e 7d Click he e o download high esolu ion image Figu e 8 Click he e o download high esolu ion image Figu e 9a Click he e o download high esolu ion image Figu e 9b Click he e o download high esolu ion image