Influence of microstructure on the enhancement of soft magnetic character and the induced anisotropy of field annealed HITPERM-type alloys

In luence o mic os uc u e on he enhancemen o so magne ic cha ac e and he induced aniso opy o ield annealed HITPERM- ype alloys J. S. Blázquez, J. Ma cin, M. Va ga, V. F anco, A. Conde, and I. Sko anek Ci a ion: Jou nal o Applied Physics 117, 17A301 (2015); doi: 10.1063/1.4906173 View online: h p://dx.doi.o g/10.1063/1.4906173 View Table o Con en s: h p://sci a ion.aip.o g/con en /aip/jou nal/jap/117/17? e =pd co Published by he AIP Publishing A icles you may be in e es ed in E ec o magne ic ield annealing me hods on so magne ic p ope ies o nanoc ys alline (Fe0.5Co0.5)73.5Si13.5B9Nb3Cu1 alloy J. Appl. Phys. 117, 17B729 (2015); 10.1063/1.4917324 Magne ic domains and annealing-induced magne ic aniso opy in nanoc ys alline so magne ic ma e ials J. Appl. Phys. 103, 07E730 (2008); 10.1063/1.2835068 Val e beha io o gian magne oimpedance in ield-annealed Co 70 Fe 5 Si 15 Nb 2.2 Cu 0.8 B 7 amo phous ibbon J. Appl. Phys. 97, 10M108 (2005); 10.1063/1.1854891 Imp o emen o magne ic so ness in nanoc ys alline so magne ic ma e ials by o a ing magne ic ield annealing J. Appl. Phys. 97, 10F503 (2005); 10.1063/1.1854255 E ec o s ess and/o ield annealing on he magne ic beha io o he ( Co 77 Si 13.5 B 9.5 ) 90 Fe 7 Nb 3 amo phous alloy J. Appl. Phys. 97, 034911 (2005); 10.1063/1.1845577 [This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o ] IP: 150.214.182.17 On: Mon, 01 Feb 2016 10:06:16 In luence o mic os uc u e on he enhancemen o so magne ic cha ac e and he induced aniso opy o ield annealed HITPERM- ype alloys J. S. Bl azquez, 1 J. Ma cin, 2 M. Va ga, 2 V. F anco, 1,a) A. Conde, 1 and I. Sko anek 2 1 Depa amen o de F ısica de la Ma e ia Condensada, ICM-SE CSIC, Uni e sidad de Se illa, P. O. Box 1065, 41080 Se illa, Spain 2 Ins i u e o Expe imen al Physics, Slo ak Academy o Sciences, SK-040 01 Kosice, Slo akia (P esen ed 5 No embe 2014; ecei ed 4 Sep embe 2014; accep ed 15 Sep embe 2014; published online 14 Janua y 2015) Hi pe m- ype apidly quenched ibbons we e submi ed o ield annealing, bo h longi udinal ield (LF) and ans e sal ield (TF) o he axis o he ibbon. LF annealing yields a educ ion o he magne ic aniso opy and esul s can be explained in he ame o andom aniso opy model. A coe ci i y o 3 A/m is ob ained o Fe 39 Co 39 Nb 6 B 15 Cu 1 alloy. The addi ion o Cu o hese Nb-con aining Hi pe m- ype alloys is a key ac o o e ine he mic os uc u e in o de o each his e y low coe ci i y alue. TF annealing p oduces samples wi h shea ed hys e esis loops sui able o senso and high equency applica ions. V C2015 AIP Publishing LLC. [h p://dx.doi.o g/10.1063/1.4906173] So magne ic nanoc ys alline alloys a e o med by e - omagne ic a-Fe ype nanoc ys als embedded in a esidual amo phous ma ix. As empe a u e inc eases abo e he Cu ie empe a u e o he amo phous phase (T C Am ), he coupling be ween nanoc ys als becomes de e io a ed and he ul aso magne ic cha ac e o he sys em is los . In 1998, Hi pe m alloys (Fe-Co-ETM-B-Cu being ETM ¼Z , Nb, Mo, H , e c.) we e p oposed as so magne s o high empe a u e applica- ions. 1 The key pa ame e o Hi pe m alloys is a high T C am , which gene ally exceeds he onse o nanoc ys alliza ion empe a u e. The e o e, in o de o achie e he nanoc ys al- line mic os uc u e, Hi pe m alloys ha e o be annealed below T C am implying a s abiliza ion o he magne ic domain walls due o he pai o de ing mechanism. 2,3 In gene al, his p ocedu e leads o a magne ic ha dening o he sys em. 4,5 Howe e , i has been shown ha ield annealing is e y e ec i e o a oid his ha dening in Hi pe m alloys. 6–11 In ac , as he sample is magne ically sa u a ed du ing he annealing p ocess, s abiliza ion o domain walls is a oided and coe ci i ies below 10 A/m a e ob ained o longi udinal ield (LF) annealed Hi pe m alloys. Amo phous ibbons (15 lm hick) o Fe 78x Co x Nb 6 B 16y Cu y (x ¼39, 60; y ¼0, 1) we e p oduced by mel - spinning. Pieces 60 mm long, 5 mm wide, and 20 lm hick we e annealed du ing 1 h a he peak empe a u e o he nano- c ys alliza ion p ocess de ec ed by di e en ial scanning calo- ime y (DSC) unde h ee di e en condi ions: (a) ze o magne ic ield (ZF), (b) applying 20 kA/m LF, and (c) apply- ing 640 kA/m ans e sal ield (TF) in he plane o he ibbon. Hys e esis loops we e acqui ed using a Fo s e ype B-H loop ace based on lux-ga e magne ome e . In he Nb-con aining Hi pe m alloys wi h 39 a . % Co con en , addi ion o 1 a . % Cu leads o a e inemen o he mic os uc u e and he a e age c ys al size educes om D¼7.5 nm o 5 nm a e Cu addi ion, whe eas c ys alline ac ion a e he nanoc ys alliza ion emains una ec ed (X C 55%). Howe e , o alloys wi h 60 a . % Co, c ys alline ac ion dec eases (X C 45%) due o exhaus ion o Fe in he emaining amo phous ma ix and D¼5 nm. 12 FIG. 1. Hys e esis loops o AQ amo phous and annealed nanoc ys alline samples o Fe 78x Co x Nb 6 B 16y Cu y alloys ((a) x ¼39 and y ¼1; (b) x ¼39 and y ¼0; (c) x ¼18 and y ¼1). Symbols a e plo ed each 25 da a poin s o iden i y he cu es. A magni ied iew is shown in he inse s o app ecia e he coe ci i y. Symbols in he inse co espond o indi idual (H) da a. a) Au ho o whom co espondence should be add essed. Elec onic mail: [email p o ec ed]. 0021-8979/2015/117(17)/17A301/3/$30.00 V C2015 AIP Publishing LLC117, 17A301-1 JOURNAL OF APPLIED PHYSICS 117, 17A301 (2015) [This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o ] IP: 150.214.182.17 On: Mon, 01 Feb 2016 10:06:16 Figu e 1shows he hys e esis loops o nanoc ys alline samples o he h ee s udied composi ions o ZF and LF annealing along wi h he co esponding hys e esis loops o he as-quenched (AQ) amo phous alloy. I can be obse ed ha LF samples exhibi a squa e hys e esis loop and show a clea so ening o he magne ic cha ac e wi h espec o ZF annealed samples. A clea inc ease o sa u a ion magne iza- ion (M S ) is obse ed a e nanoc ys alliza ion due o he o - ma ion o he a-FeCo phase. Howe e , ZF annealed samples show a clea de e io a ion o he coe ci i y (H C ) wi h espec o AQ alloys due o he mechanism o pai o de ing. Low coe ci i ies o AQ samples a e p ese ed o e en imp o ed a e LF annealing (e.g., o x ¼39, y ¼1 alloy, H C ¼3.1 A/ m compa ed o 9.8 A/m and 45 A/m o AQ and ZF samples). The mic os uc u al dependence o he obse ed mag- ne ic da a can be analyzed in he amewo k o he andom aniso opy model conside ing i s ex ension o wo-phase sys- ems. 13,14 In his con ex , he magne oc ys alline aniso opy a e ages ou due o he small size o he c ys alli es (smalle han he exchange leng h) and i can be w i en as a unc ion o he magne oc ys alline aniso opy, K 1 , he exchange s i - ness, A, and he mic os uc u al pa ame e s Dand X C 13 hKi¼ 3 4  3K4 1D6 A3XC2:(1) This exp ession p edic s a dec ease o he a e age mag- ne ic aniso opy, hKi, and hus o H C ,asDdec eases, which is in ag eemen wi h he obse ed di e ence be ween H C alues o 39 a . % Co alloys wi h and wi hou Cu. These wo sys ems ha e he same olume ac ion and composi ion o he c ys alline phase bu a la ge Dis obse ed o he Cu- ee alloy. The change in he e ec i e magne ic aniso opy, K e l 0 M S H C , can be compa ed o he expec ed change o his a e aged aniso opy hKi. A simple calcula ion imposing K 1 10 kJ/m 3 (Re . 15) o a Fe 0.61 Co 0.39 composi ion and he mic os uc u al pa ame e s collec ed in Table Ileads o a alue o A0.5 10 11 J/m, which is in good ag eemen wi h he expec ed alue. The wo s udied Cu-con aining alloys show D¼5nm. In he case o he alloy wi h 60 a . % Co, a dec ease in X C wi h espec o he alloy wi h 39 a . % Co alloys should imply a dec ease in hKi o a cons an alue o D¼5 nm, in disag ee- men wi h he obse ed end. The explana ion o his appa- en con adic ion is he di e en composi ion o he c ys alline phases, which yields di e en alues o K 1 .In ac , exp ession (1) shows a s onge dependence on K 1 han on X C . The alue o K 1 depends on he composi ion o he a-FeCo phase, being 50 kJ/m 3 o pu e a-Fe and dec easing as Co con en inc eases down o 40 kJ/m 3 o 70 a . % Co. 15 The e o e, assuming ha he composi ions o nanoc ys als a e Fe 0.61 Co 0.39 and Fe 0.4 Co 0.6 o he alloys wi h 39 and 60 a . % Co, espec i ely, 16 K 1 can be es ima ed as þ10 kJ/m 3 and 20 kJ/m 3 o x ¼39 and 60 alloys, espec i ely, 15 which explains he obse ed di e ence. Figu e 2shows he hys e esis loops o TF annealed sam- ples, which show shea ed loops, almos linea up o he ani- so opy ield, H k , whe e M S is eached. This indica es ha o a ion o magne ic momen s is he dominan mechanism o magne iza ion in hese samples. Such ype o hys e esis loops is especially in e es ing o senso applica ions, TABLE I. Pa ame e s o nanoc ys alline samples ob ained a e annealing a T a . Composi ion T a (K) D(nm) X C (%) C ys al phase composi ion K 1 (kJ/m 3 )q(g/cm 3 ) Fe 39 Co 39 Nb 6 B 15 Cu 1 739 5 55 Fe 0.61 Co 0.39 10 8.1 Fe 39 Co 39 Nb 6 B 16 766 7.5 55 Fe 0.61 Co 0.39 10 8.1 Fe 18 Co 60 Nb 6 B 15 Cu 1 736 5 45 Fe 0.4 Co 0.6 20 8.3 FIG. 2. Hys e esis loops o ans e sal ield annealed samples o he h ee s udied composi ions. FIG. 3. Sucksmi h-Thompson plo o he h ee s udied composi ions submi - ed o ans e sal ield annealing. Lines co espond o linea i ings. 17A301-2 Bl azquez e al. J. Appl. Phys. 117, 17A301 (2015) [This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o ] IP: 150.214.182.17 On: Mon, 01 Feb 2016 10:06:16 whe eas he educed suscep ibili y makes hese samples in e es ing o high equency ans o me applica ions. 17 In o de o cha ac e ize he sensi i eness o TF anneal- ing p ocess, he induced magne ic aniso opy, K u , has been cha ac e ized using se e al p ocedu es. On he one hand, K u can be di ec ly es ima ed om he alue o he aniso opy ield, H k , as: Ku¼l0MSHk=2, whe e H k has been es ima ed as he linea ex apola ion o each M S .K u ¼860, 1170, and 1090 J/m 3 o x ¼39, y ¼1; x ¼39, y ¼0, and x ¼18, y ¼1 alloys, espec i ely. On he o he hand, he me hod o Sucksmi h and Thompson 18 allows us o ob ain he wo i s coe icien s o he magne ic aniso opy K 1u and K 2u based on he ela ion 2K1u l0MS ðÞ 2þ4K2u l0MS ðÞ 4l0MH ðÞ  2¼H l0MH ðÞ ;(2) whe e M(H) ep esen s he magne iza ion a a gi en ield H. The e o e, ollowing exp ession (3), Figu e 3shows he plo o H/(l 0 M) s(l 0 M) 2 om which K 1u can be ob ained om he alue o he in e cep wi h he y axis and K 2u om he slope o he cu e. The ob ained alues a e in ag eemen wi h he p e ious ones. K 1u ¼849.0(5), 1182.5(6), and 1108.7(8) J/m 3 o x ¼39, y ¼1; x ¼39, y ¼0, and x ¼18, y¼1 alloys, espec i ely. Finally, a s udy on he dis ibu ion o aniso opy ields, P(H k ), can be done om he second de i a i e o he mag- ne iza ion cu e using he wo b anches om sa u a ion o emanence, as i has been desc ibed o amo phous 19 and nanoc ys alline sys ems 20 PH k ðÞ¼ H MS d2MH ðÞ dH2:(3) The co esponding plo s a e shown in Figu e 4. The e a e no signi ican di e ences in he wid h o he dis ibu ion, al hough i is smalle in he alloy wi h he highes Co con en . I can be obse ed ha K u ollows he same end han he esidual K e obse ed in LF annealed samples and desc ibed abo e. The smalles alue o K u (o K u1 ) is ound o he alloy wi h 39 a . % Co and 1 a . % Cu, whe eas he la ges alue o induced aniso opy is ound o he Cu- ee alloy. In conclusion, he magne ic ha dening obse ed in ZF nanoc ys alline samples is p e en ed a e ield annealing in he sa u a ion s a e and a minimum H C ¼3A/mhas been ob ained o LF which equal he bes H C alues epo edup oda e o Fe 38 Co 38 Mo 8 B 15 Cu 1 Hi pe m alloys. 8 Mic os uc u al and composi ional di e ences be ween he s udied alloys can explain he di e ences obse ed in hei magne ic p ope ies. On he o he hand, whe eas LF yields a minimiza ion o hKiand squa e hys- e esis loops, TF annealing p oduces samples wi h shea ed hys e esis loops, which would be in e es ing o senso and high equency applica ions. Wo k suppo ed by NANOKOP N . ITMS 26110230061 NanoCEXma N . ITMS 26220120019 p ojec s, he Slo ak Agency o he Resea ch and De elopmen (P ojec Nos. APVV-0266-10 and APVV-0492-11), MNT ERA NET II STREAM, he Spanish MINECO and EU FEDER (P ojec No. MAT 2013-45165-P), and he PAI o he Regional Go e nmen o Andaluc ıa (P ojec No. P10-FQM-6462). 1 M. A. Willa d e al.,J. Appl. Phys. 84, 6773 (1998). 2 L. N eel, J. Phys. Radium 15, 225 (1954). 3 S. Taniguchi and M. Yamamo o, Sci. Rep. Res. Ins ., Tohoku Uni ., Se . A6, 330 (1954). 4 J. S. Bl azquez e al.,J. Magn. Magn. Ma e . 250, 260 (2002). 5 T. Kulik e al.,J. Alloys Compd. 434, 623 (2007). 6 I. Sko anek e al.,J. Magn. Magn. Ma e . 304, 203 (2006). 7 I. Sko anek e al.,J. Magn. Magn. Ma e . 310, 2494 (2007). 8 I. Sko anek e al.,J. Alloys Compd. 504, S135 (2010). 9 I. Sko anek e al., Magne ohyd odynamics 48, 371 (2012). 10 F. Johnson e al.,IEEE T ans. Magn. 40, 2697 (2004). 11 K. Suzuki e al.,J. Non-C ys . Solids 354, 5089 (2008). 12 J. S. Bl azquez e al.,J. Phys.: Condens. Ma e 14, 11717 (2002). 13 K. Suzuki and J. M. Cadogan, Phys. Re . B 58, 2730 (1998). 14 A. He nando e al.,Phys. Re . B 51, 3581 (1995). 15 D. Bonnenbe g e al., in 1.2.1.2.7 Magne oc ys alline aniso opy edi ed by H. P. J. Wijn, Landol -B€ o ns ein Da abase Vol. 19a (Sp inge , Heidelbe g, 1986), p. 210. 16 Y. Zhang e al.,Ma e . Sci. Eng. A 353, 158 (2003). 17 A. M. Lea y e al.,JOM 64, 772 (2012). 18 K. H. J. Buschow and F. R. de Boe , Physics o Magne ism and Magne ic Ma e ials (Kluwe Academic/Plenum Publishe s, London, 2003), p. 99. 19 J. M. Ba andia  an e al.,IEEE T ans. Magn. 25, 3330 (1989). 20 V. F anco e al.,J. Magn. Magn. Ma e . 185, 353 (1998). FIG. 4. P obabili y dis ibu ion o aniso opy ields om he second de i a- i e o he magne iza ion cu e om sa u a ion o emanence (da a shown co espond o a smoo hing using en neighbo ing poin s). 17A301-3 Bl azquez e al. J. Appl. Phys. 117, 17A301 (2015) [This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o ] IP: 150.214.182.17 On: Mon, 01 Feb 2016 10:06:16