Evolution of Fe environments and phase composition during mechanical amorphization of Fe70Zr30 and Fe70Nb30 alloys

Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 1 E olu ion o Fe en i onmen s and phase composi ion du ing mechanical amo phiza ion o Fe70Z 30 and Fe70Nb30 alloys A. F. Manchón-Go dón, J. J. Ipus, J. S. Blázquez*, C. F. Conde, A. Conde Dp o. Física de la Ma e ia Condensada, ICMSE-CSIC, Uni e sidad de Se illa, P.O. Box 1065, 41080 Se illa, Spain * The co esponding au ho e-mail: [email protected] ABSTRACT: Amo phous Fe-Z and Fe-Nb alloys wi h 70 a . % Fe ha e been p epa ed by ball milling a mix u e o elemen al powde s. The combina ion o Mössbaue spec oscopy, X- ay di ac ion, scanning elec on mic oscopy and di e en ial scanning calo ime y echniques supplies de ailed in o ma ion abou he composi ion as well as mic os uc u al pa ame e s o emaining c ys alline and amo phous phases de eloped du ing milling. De ailed analysis o he Fe en i onmen s allows us o dis inguish Fe a oms in pa amagne ic si es be ween hose inco po a ed o c ys alline Z o Nb ich phases and hose Fe a oms in amo phous phase. KEYWORDS: mechanical amo phiza ion, mechanical alloying, amo phous alloys 1. INTRODUCTION Ad anced ma e ials can be de ined as hose ha ep esen supe io p ope ies o e he adi ional ma e ials o demanding applica ions. Typically, p og ess on imp o ing he p ope ies o hese ma e ials is gi en hanks o he sys ema ic syn hesis and con ol o he s uc u e o he ma e ials [1] p ocessing hem unde non-equilib ium condi ions [2]. Among he di e en p ocesses in comme cial use, mechanical alloying (MA) [2], plasma p ocessing [3] o apid solidi ica ion om he liquid s a e [4] can be signed. MA echnique, o iginally de eloped o p oduce oxide-dispe sion s eng hened nickel and i on base supe alloys o applica ions in he ae ospace indus y [5], has a unique Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 2 capabili y o p oducing he modynamically dis a o ed eac ions and des abilizing equilib ium sys ems [2]. In ac , he la ge di e si y o me as able sys ems ha can be p oduced by MA, including amo phous alloys, supe sa u a ed solid solu ions o me as able in e me allics, makes his echnique o be p esen in many esea ch ields [2, 6]. Gene ally, high ene ge ic milling o alloys leads o he o ma ion o a nanoc ys alline s uc u e and, o some composi ions, o amo phiza ion [2]. I on-based sys ems a e among he mos sui able ma e ials o s udying he mechanical milling as a p ocess and he p ope ies o he inal p oduc s. The cheap cha ac e o his elemen makes i desi able and ubiqui ous in any echnological ield. The magne ic na u e o many compounds o i on signi ican ly inc eases he amoun o in o ma ion ha can be ob ained o hese sys ems. Mo eo e , he exis ence o a Mössbaue iso ope, 57Fe, in a non-negligible na u al abundancy [7] makes possible he s udy o hype ine in e ac ions o Fe-compounds. The e o e, all his leads o a mo e comp ehensi e unde s anding o he ma e ial. Pa icula ly, he Fe-Z alloys p esen ex emely di e en magne ic p ope ies depending on Fe con en [8, 9] and he local a omic o de [10], as well as a wide ange o he exis ence o he amo phous phase, FexZ 100-x (20≤x≤93 a . %) [11]. In he case o he Fe-Nb alloys, al hough s ill some esea ch is needed o de e mine a comple e phase diag am [12], amo phous phase is ound in a wide composi ional ange [13, 14]. These phases show in e es ing peculia i ies due o singula aspec s o hei nanos uc u es [15]. In a p e ious s udy [16] we used Fe70Z 30 and Fe70Nb30 (a . %) composi ions o show he alidi y o he cubic law [17] ha co ela es he p og ess o milling wi h he equency o he mill. Mic os uc u al and composi ional cha ac e iza ion o amo phous s uc u es is an essen ial poin o op imize echnological p ope ies in which hey a e based on. Howe e , his cha ac e iza ion is c i ical o nanoscale sys ems, o which he Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 3 cha ac e is ic size o be s udied is so iny ha could p esumably only be a ainable o nanop obe echniques. O he wise, due o he ex emely local cha ac e o a om-scale echniques, s a is ics using iny p obes a e no s aigh o wa d. Fo example, in he analysis o a nanoc ys al using a om p obe, he sensi i i y in he composi ion is no as good as o sys ems wi h a well-de ined la in e ace. Assuming a 5 nm sphe e, he ange no a ec ed by he su ace geome y is limi ed o a cube o 5/√3 nm in size. In he case o a bcc-Fe phase, his implies a leng h o only ~10 uni cells. On he o he hand, me hods based on global echniques (X- ay di ac ion, Mössbaue spec oscopy, e c.) p esen he ad an age o a much be e s a is ics o ob ain a e age alues and a e expe imen al echniques accessible o mos o he scien i ic communi y. In ac , he capabili y o Mössbaue spec oscopy o analyze nanoscale sys ems ha e been poin ed ou , pa icula ly when combining wi h o he echniques, such as X- ay di ac ion [18, 19]. Cu en ly, he e a e many in es iga ions on amo phous Fe-Z and Fe-Nb phases ob ained by di e en echniques and on he s uc u al analysis o he p oduc s o mechanical alloying in hese sys ems [10, 14, 20-24]. Howe e , no sys ema ic s udy o he composi ion o bo h amo phous and emnan bcc nanoc ys als in Fe-based supe sa u a ed solid solu ions ha e been unde aken. In ou case, we combined XRD and Mössbaue da a o es ima e he composi ions o nanoc ys als in FeNbB supe sa u a ed solid solu ion [19]. I is wo h men ioning ha he knowledge o he composi ion o he di e en phases is e y help ul o p opose accu a e models o desc ibe he beha io o any physical sys em. In he p esen wo k, amo phous Fe-Z and Fe-Nb alloys wi h 70 a . % Fe ha e been p epa ed using mechanical alloying. The mic os uc u al e olu ion o bo h alloys was ollowed by Mössbaue spec oscopy, X- ay di ac ion, scanning elec on mic oscopy and di e en ial scanning calo ime y. The Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 4 combina ion o hese echniques supplies e y de ailed in o ma ion abou he composi ion o nanoc ys als and he amo phous phase de eloped du ing mechanical alloying. Mo eo e , om he e olu ion o he composi ions o nanoc ys als co e i has been possible o es ima e he in e ace hickness. 2. EXPERIMENTAL Fe-Z and Fe-Nb alloys wi h 70 a . % Fe we e p epa ed by ball milling o elemen al powde s mix u e in a plane a y mill F i sch Pul e ise e Va io 4 using ha dened s eel balls and s eel ials. The ini ial powde mass was 30 g, he ball o powde a io 10:1 and he a io be ween he o a ional speeds o he ials and he main disk -2. Con inuous milling s eps o 0.5 h we e pe o med in A a mosphe e and a e selec ed imes, app oxima ely 0.2 g o sample was ex ac ed in a Sa on Omega glo e box wi h oxygen and humidi y le els below 2 ppm unde A a mosphe e. The mic os uc u e was s udied by X- ay di ac ion (XRD) using Cu-Kα adia ion in a B uke D8 I di ac ome e . Di e en ial scanning calo ime y (DSC) was pe o med in a TA-Ins umen s Q600 SDT unde ni ogen low. The powde samples we e p essed in sil e capsules and a baseline was ob ained using a s anda d Ag sample. Pa icle size dis ibu ion and mo phology was s udied by scanning elec on mic oscopy (SEM) in seconda y elec ons mode pe o med in a Jeol 6460 LV mic oscope ope a ed a 30 kV. The local en i onmen o Fe a oms was analyzed by Mössbaue spec ome y (MS) in ansmission geome y a oom empe a u e (RT) using a 57Co(Rh) sou ce. Values o he hype ine pa ame e s we e ob ained by i ing wi h NORMOS p og am [25] and he isome shi (𝐼𝑆) was quo ed ela i e o he Mössbaue spec um o an α-Fe oil a RT. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 5 3. RESULTS and DISCUSSION 3.1. X- ay di ac ion esul s XRD pa e ns o Fe70Z 30 and Fe70Nb30 alloys a e selec ed milling imes a e p esen ed in igu e 1. The amo phous phase o he as-milled samples is e idenced by a wide amo phous halo in samples milled o a leas 𝑡 =6 and 9 h, o Fe70Z 30 and Fe70Nb30, espec i ely. XRD does no clea ly show he expec ed displacemen o lowe angles o bcc Fe di ac ion maxima ha should indica e an inc ease o he la ice pa ame e , 𝑎, as Z o Nb a oms become in eg a ed in o he bcc Fe(Z ) and Fe(Nb) solid solu ion, espec i ely, al hough a sligh e ec can be obse ed a sho imes. The bcc Fe maxima ge b oade as milling ime inc eases due o he educ ion o he c ys al size and he inc ease o mic os ains du ing milling. Peaks a ibu ed o he hcp Z and bcc Nb phases a e only de ec ed o sho milling imes (𝑡 <6 and 𝑡 <12 h o Fe70Z 30 and Fe70Nb30, espec i ely). The e olu ion o he amo phous phase wi h milling ime was es ima ed om a decon olu ion o he main X- ay peak o sepa a e he (110) line o he 𝛼-Fe nanoc ys als (na ow Lo en zian con ibu ion) and he amo phous halo (b oad Gaussian con ibu ion). The e o e, he amo phous olume ac ion can be es ima ed as he a ea o he Gaussian con ibu ion (amo phous halo) di ided by he whole a ea o he expe imen al di ac ion peak. In he case o he Fe70Nb30 alloy, o sho milling imes (𝑡 <12 h), i is necessa y o ake in o accoun he con ibu ion o he (110) peak o he bcc Nb nanoc ys als. Figu e 2 shows he e olu ion o he c ys al size, 𝐷, es ima ed om Sche e ’s o mula om he ull wid h a hal maximum o c ys alline (110) di ac ion peak, as a unc ion o milling ime o bo h alloys along wi h ha o Nb phase o Fe70Nb30 alloy. Final 𝐷 Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 6 o bcc-Fe ype phase is clea ly la ge o Fe70Z 30 alloy, o which a s able alue ~10 nm is apidly achie ed, meanwhile 𝐷 con inuously dec eases down o ~5 nm o he Nb-con aining alloy. The e olu ion o he la ice pa ame e o he 𝛼-Fe(X), being X=Z , Nb, as a unc ion o milling ime is shown in igu e 3. As commen ed abo e, he expec ed inc ease in la ice pa ame e is clea e o Fe70Nb30 han o Fe70Z 30 alloy. The posi ion o he amo phous halo shi s o highe 2𝜃 alues as milling p og esses ( igu e 4a). This indica es a con ac ion o he a e age me al-me al dis ance ( igu e 4b), which can be es ima ed as [26]: 𝛿𝑀−𝑀 =5𝜆 8sin𝜃 (1) whe e 𝜆 is he wa eleng h o he used adia ion. 3.2. Di e en ial scanning calo ime y esul s In o de o e i y he o ma ion o he amo phous s uc u e, DSC cu es o bo h s udied alloys we e eco ded in non-iso he mal egime. Figu e 5 shows he DSC scans a 20 K/min o bo h s udied samples a e ~50 h o milling. All he ea u es ound in he cu es a e i e e sible as hey anish in a second hea ing. The well-de ined exo he mic peaks a ound 950 and 1000 K o Z and Nb con aining alloys, espec i ely, co espond o c ys alliza ion o he amo phous phase. P e ious de ia ions om baseline a e asc ibed o elaxa ion phenomena in ag eemen wi h he li e a u e [9, 17]. The ob ained alues o he onse empe a u es 𝑇𝑜𝑛𝑠𝑒𝑡 and peak empe a u es 𝑇𝑝𝑒𝑎𝑘 o c ys alliza ion p ocess a e shown in Table 1. The alues ob ained o he Fe70Z 30 alloy a e simila o hose epo ed by Mish a e al. [9]. Howe e , 𝑇𝑜𝑛𝑠𝑒𝑡 o powde samples a e sligh ly highe han hose ob ained o ibbon samples [27]. In he case o he Nb con aining alloy, he alues ob ained a e close o hose epo ed by El-Eskanda any e al. [22] o amo phous Fe52Nb48 alloy powde . Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 7 3.3.Scanning elec on mic oscopy esul s Mic os uc u al modi ica ions induced by milling can be ollowed om a di ec compa ison o he seconda y elec on images ( igu e 6) o he wo s udied alloys. These show he exis ence o agglome a es a ea ly milling imes (𝑡 =6 and 8.5 h o Fe70Z 30 and Fe70Nb30, espec i ely), meanwhile a longe milling imes (𝑡 >22 h) almos sphe ical isola ed powde pa icles a e ound. Al hough hose agglome a es a e p esen in bo h samples, o Fe70Nb30 he size o pa icles is la ge and he numbe o pa icles pe agglome a e is smalle han o Fe70Z 30 samples o equi alen milling imes (e.g. a e ~20 h milling, Fe70Nb30 alloy shows ew ens o pa icles pe agglome a e, meanwhile Fe70Z 30 shows ew hund eds o pa icles pe agglome a e). Inse s o igu e 6 show he co esponding g ain size dis ibu ion his og ams. The pa icle size a e di e en milling imes was ob ained by a e aging o e a minimum o 50 pa icles o each sample. Pa icle size dec eases wi h milling un il 22 h, achie ing sizes abou d~12±4 and 33±13 𝜇m o Fe70Z 30 and Fe70Nb30, espec i ely. A e his ime o milling, he pa icle size inc eases, inally eaching sizes abou d~23±11 and 44±18 𝜇m o Fe70Z 30 and Fe70Nb30, espec i ely. Fo agglome a es he e is no a clea endency, being hei sizes be ween 50-200 𝜇m o bo h alloys when hey a e p esen . 3.4. Mössbaue spec oscopy esul s Figu e 7 shows he e olu ion o he oom empe a u e Mössbaue spec a wi h milling ime. Two e omagne ic si es we e used o i he esidual α-Fe(X) phase: a sex e wi h hype ine ield, 𝐻𝐹=33 T (no X a oms in he neighbo hood), and ano he wi h 𝐻𝐹=30.5 T (one X a om in he neighbo hood). A quad upola dis ibu ion was used o desc ibe he pa amagne ic con ibu ions, a p io i assigned o he amo phous phase. Mo eo e , a dis ibu ion o hype ine ields om 5 o 30 T was used o show he con ibu ion om Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 8 he in e ace egion and iche X neighbo hoods. Figu e 8 shows he ac ion o he Fe a oms con ibu ing o each en i onmen ype. The ac ion o he pa amagne ic con ibu ions shows a con inuous inc ease as milling ime p og esses. Figu e 9 shows he a e age isome shi (<𝐼𝑆>) o he pa amagne ic con ibu ions as a unc ion o milling ime o bo h s udied alloys, ei he Z o Nb play a simila ole and alues o his pa ame e show a common beha io o he wo alloys. Ini ially, o sho imes o milling, o which hcp Z and bcc Nb phases a e de ec ed by XRD, a educ ion o <𝐼𝑆> om 0 o ~−0.18 mm/s is obse ed. Values show a common beha io o bo h alloys a e he peaks a ibu ed o he hcp Z o bcc Nb phase in XRD pa e ns disappea . A e u he milling, <𝐼𝑆> eaches a s able alue ~−0.15 mm/s o bo h samples. The alues ob ained o he Fe70Z 30 alloy ag ee wi h hose epo ed o he amo phous alloys Fe65Z 35 (𝛿 = −0.16 mm/s) [20] and Fe70Z 30 (𝛿 = −0.16 mm/s) [16], bu sligh ly highe alues we e epo ed o Fe73Z 27 (𝛿 = −0.13 mm/s) [21] and Fe2Z (𝛿 = −0.13 mm/s) [10]. The alues ob ained o he Fe70Nb30 alloy also ag ee wi h hose epo ed o he amo phous alloy wi h he same composi ion (𝛿 = −0.16 mm/s) [16] and Fe80Nb20 (𝛿 = −0.17 mm/s) [14]. Howe e , Eskanda any e al. obse ed an isome shi 𝛿 = −0.19 mm/s in amo phous samples o Fe52Nb48 p epa ed by mechanical alloying [22]. In ac , he sligh ly inc ease in <𝐼𝑆> om he obse ed minimum could be asc ibed o he Fe en ichmen o he amo phous phase as milling p og esses. The quad upole spli ing dis ibu ions, 𝑃(𝑄𝑆), a e shown in igu e 10. I shows he same beha io o bo h alloys, wi h a non-ze o p obabili y o 𝑄𝑆=0 mm/s. They also p esen wo well esol ed maxima o sho imes o milling (𝑡 <6 and 𝑡 <10 h o he Fe70Z 30 and Fe70Nb30 alloy, espec i ely) ha become only one wi h he inc ease o milling Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 9 ime. The i s peak (𝑄𝑆~0.25 mm/s) may be asc ibed o Fe a oms in en i onmen s simila o Fe2X. This en i onmen , o X=Z has 𝑄𝑆=0.35 mm/s (𝛿 = −0.13 mm/s) [10] and o X=Nb has 𝑄𝑆=0.34 mm/s (𝛿 = −0.19 mm/s) [24]. The second maximum ound a low milling imes (𝑄𝑆~1.25 mm/s) may be a ibu ed o X iche en i onmen s, e.g. Vincze e al. [28] epo ed 𝑄𝑆=0.91 mm/s o FeZ 3. Wi h hese da a, we can admi ha 𝑄𝑆 dis ibu ions o low milling imes do no eally co espond o amo phous phase, bu o Fe p esen in Z and Nb emaining c ys als ( he imes a which his wo-peak 𝑃(𝑄𝑆) a e obse ed a e in ag eemen wi h he obse a ion o bcc Nb and hcp Z phases by XRD). Fo la ge milling imes, a alue o <𝑄𝑆>=0.53±0.07 mm/s is ob ained o bo h alloys. This alue is close o he alues p e iously epo ed o Fe70Z 30 (<𝑄𝑆>=0.44 mm/s) and o Fe70Nb30 (<𝑄𝑆>=0.42 mm/s) [16]. Taking in o accoun he nanoc ys alline mic os uc u e o ou samples, some wo ds on supe pa amagne ism a e needed. An ensemble o magne ic nanopa icles shows supe pa amagne ic beha io abo e a ce ain empe a u e: he blocking empe a u e 𝑇𝐵. This empe a u e is de ined as he empe a u e a which he elaxa ion ime 𝜏 equals he expe imen imescale 𝜏𝑚 [29]: 𝑇𝐵=∆𝐸 𝑘𝐵𝑙𝑛( 𝜏 𝑚 𝜏0) (2) whe e ∆𝐸 is he ene gy ba ie ha he magne iza ion lip has o o e come by he mal ene gy and can be conside ed o be p opo ional o he magne ic aniso opy cons an K and pa icle olume V (∆𝐸 = 𝐾𝑉), 𝑘𝐵 is he Bol zmann cons an and 𝜏0 is he leng h o ime cha ac e is ic o he p obed ma e ial. Al hough supe pa amagne ism should be expec ed o quasis a ic measu emen s (𝜏𝑚~100 s) abo e Cu ie empe a u e 𝑇𝐶 o he amo phous phase, i is wo h no ing ha in Mössbaue spec oscopy 𝜏𝑚~𝜏0. Mo eo e , Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 16 [19] Blázquez JS, Ipus JJ, F anco V, Conde CF, Conde A. Ex ac ing he composi ion o nanoc ys als o mechanically alloyed sys ems using Mossbaue spec oscopy. 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Solid s a e amo phiza ion ans o ma ion in he mechanically alloyed Fe27.9Nb2.2B69.9 powde s. Ma e ials Chemis y and Physics 2010;122:35-40 h ps://doi.o g/10.1016/j.ma chemphys.2010.03.006 Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 17 FIGURES 30 40 50 60 70 80 90 100 110 120 30 40 50 60 70 80 90 100 110 120 Fe hcp-Z 1.5 h 50 h 35 h 22 h 16 h 12 h 8.5 h 6 h 2(deg ees) bcc Nb b) 49.5 h 21.5 h 34.5 h 15 h 12 h 9 h 6 h 2(deg ees) 1.5 h a) Figu e 1. XRD pa e ns o he amo phous samples a e milling up o di e en imes o a) Fe70Z 30 and b) Fe70Nb30. 0 2 4 6 8 10 12 14 16 18 20 22 0 5 10 15 20 25 30 0 2 4 6 8 10 12 14 16 18 20 22 0 5 10 15 20 25 30 D (nm) milling ime (h) b) Fe(Nb) Nb (Fe) D (nm) milling ime (h) a) Figu e 2. E olu ion o c ys al size o he a) Fe(Z ) and b) Fe(Nb) and Nb(Fe) ( igh ) bcc phases as a unc ion o milling ime. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 18 0 5 10 15 20 25 2.86 2.87 2.88 2.89 2.90 Fe(Z ) Fe(Nb) a (10-10 m) milling ime (h) Figu e 3. E olu ion o la ice pa ame e o he Fe(Z ) and Fe(Nb) bcc phases as a unc ion o milling ime. 010 20 30 40 50 39.0 39.5 40.0 40.5 41.0 41.5 42.0 42.5 43.0 010 20 30 40 50 2.5 2.6 2.7 2.8 2.9 Fe70Z 30 Fe70Nb30 Fe70Z 30 Fe70Nb30 amo phous halo posi ion (2 deg ees) milling ime (h) a) b) M-M (10-10 m) milling ime (h) Figu e 4. a) E olu ion o he amo phous halo posi ion and b) me al-me al dis ance as a unc ion o milling ime. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 19 400 600 800 1000 -1 0 1 2 3Tonse dH/d (W/g) T (K) Fe70Nb30 exo Fe70Z 30 Tonse Tpeak Tpeak Figu e 5. Non-iso he mal DSC scans a 20 K/min o bo h s udied samples a e 50 h (Z con aining alloy) and 49.5 h (Nb con aining alloy) o milling. C ys alliza ion peak and onse empe a u es a e indica ed. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 20 Figu e 6. Scanning elec on mic oscopy images in seconda y elec ons mode o he wo s udied alloys a e selec ed milling imes. Inse s show he his og ams o he powde pa icle size. 020 40 60 80 0 20 40 60 Fe70Nb30 =21.5 h p obabili y (%) d (m) 020 40 60 80 0 20 40 60 Fe70Z 30 =22 h p obabili y (%) d (m) 020 40 60 80 0 10 20 30 p obabili y (%) d (m) Fe70Z 30 =50 h 020 40 60 80 0 10 20 30 Fe70Nb30 =49.5 h p obabili y (%) d (m) Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 21 -8 -6 -4 -2 0 2 4 6 8 -8 -6 -4 -2 0 2 4 6 8 -8 -6 -4 -2 0 2 4 6 8 in ensi y (u.a.) 9 h6 h in ensi y (u.a.) eloci y (mm/s) 16 h eloci y (mm/s) 50 h 35 h eloci y (mm/s) 3 h -8 -6 -4 -2 0 2 4 6 8 -8 -6 -4 -2 0 2 4 6 8 -8 -6 -4 -2 0 2 4 6 8 9 h6 h in ensi y (a.u.) 3 h 15.5 h in ensi y (a.u.) eloci y (mm/s) 34.5 h eloci y (mm/s) 49.5 h eloci y (mm/s) Figu e 7. Expe imen al Mössbaue spec a (symbols) and model i ing (lines) o se e al milling imes: Fe70Z 30 (up), Fe70Nb30 (down). Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 22 0 5 10 15 20 25 30 35 40 45 50 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 0 10 20 30 40 50 60 70 80 90 100 ac ion a ea (%) milling ime (h) si e 1: 33 T si e 2: 30.5 T hipe ine dis ibu ion quad upola dis ibu ion a) b) ac ion a ea (%) milling ime (h) Figu e 8. Phase con ibu ion o Mössbaue spec a i ing o a) Fe70Z 30 and b) Fe70Nb30 alloys. 010 20 30 40 50 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 010 20 30 40 50 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 b) <IS> (mm/s) millig ime (h) a) <IS> (mm/s) millig ime (h) Figu e 9. A e age isome shi (<IS>) o pa amagne ic con ibu ions as a unc ion o milling ime o a) Fe70Z 30 and b) Fe70Nb30 alloys. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 23 0.0 0.5 1.0 1.5 2.0 0 10 20 30 40 50 60 70 80 90 0.0 0.5 1.0 1.5 2.0 0 10 20 30 40 50 60 70 80 90 Q (mm/s) dP(Q)/dQ (% mm-1s) 3 h 6 h 9 h 16 h 35 h 50 h Fe70Nb30 Q (mm/s) dP(Q)/dQ (% mm-1s) 3 h 6 h 9 h 15.5 h 34.5 h 49.5 h Fe70Z 30 Figu e 10. P obabili y dis ibu ion o quad upole spli ing o bo h samples a e se e al milling imes. 0 5 10 15 20 25 30 35 0 1 2 3 4 5 6 7 8 0 5 10 15 20 25 0 1 2 3 4 5 6 7 8 Z con en (%) milling ime (h) a) b) F om a io A(30.5T)/A(33T) F om Vega d's law Nb con en (%) milling ime (h) Figu e 11. a) Con en o Z inside he nanoc ys als om Mössbaue esul s and b) con en o Nb inside he nanoc ys als om Mössbaue esul s and Vega d’s law. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 24 020 40 60 80 100 0 20 40 60 80 100 020 40 60 80 100 0 20 40 60 80 100 Fe70Z 30 Fe70Nb30 XXRD AMS a) b) XXRD XMS Figu e 12. Amo phous ac ion om XRD pa e ns as a unc ion o a) he ela i e a ea o pa amagne ic con ibu ion and b) he es ima ed amo phous phase ac ion om Mössbaue spec a. The dashed lines co espond o he iden i y line. 0 5 10 15 20 25 30 35 0 20 40 60 80 100 120 140 510 15 20 25 30 0 20 40 60 80 Fe70Z 30 Fe70Nb30 R/ milling ime (h) R/ DFe (nm) Figu e 13. E olu ion o 𝑅/𝛿 as a unc ion o milling ime o bo h alloys. Inse shows he ela ion be ween 𝑅/𝛿 and 𝐷𝐹𝑒 ob ained om XRD da a. Jou nal o Non-C ys alline Solids, 494 (2018) 78-85 h ps://doi.o g/10.1016/j.jnonc ysol.2018.04.061 25 Table 1. C ys alliza ion empe a u e o s udied alloys a e 50 h (Z con aining alloy) and 49.5 h (Nb con aining alloy) o milling, espec i ely Sample 𝑻𝒐𝒏𝒔𝒆𝒕 (K) 𝑻𝒑𝒆𝒂𝒌 (K) Fe70Z 30 862 956 Fe70Nb30 980 1006