Influence of gadolinium on the microstructure and mechanical properties of steel and stainless steel

Transcription

1 Ifc f gdiim th micstct d mchic tis f st d stiss st by Z. Kh* witt jct wk cid t i ti ffimt f Bsc (Mtgic Egiig) Sysis I, i th fm f st d stiss st, is th mst cmmy sd mt i th wd. i sts cd d xidiz siy, whi stiss sts xhibit imvd csi d xidti sistc. It hs b fd tht th mt (REM) dditis, sch s cim d bim, st i th imvmt f th bvmtid tis i ictiig cmds. iim is REM, hwv, th is vy itt ifmti vib th ifc f gdiim th micstct d mchic tis f i-ctiig cmds. Ths, th s f this sch jct ws t dtmi th ifc f gdiim dditis th micstct d mchic tis f mid st d 316 stiss st. T ys w dcd f th ss f this sch. Fiv f th ys hd bs cmsiti f mid st whi th miig fiv hd bs cmsiti f 316 stiss st. Th ys f ch f th bs cmsiti ctid gdiim dditis f.1,.5, 1.2, d 5 wight ct. Th s-cst d th cd-d ys w ysd. Th ys sdd w t th cd-ig with th xcti f th 5 wight ct gdiim mid st d stiss st ys. Ths ys w xtmy bitt d dwt sigifict mt f cckig dig th cd ig css. A micstct ysis f th ys ws cdctd sig ight tic micsc, whi th chmic ysis f th ys ws cdctd sig gy dissiv x-y sctscy (EDS). Th stig micstcts d EDS yss vd tht th gdiim disyd miim sbiity i th fit mtix f th mid st ys d miim sbiity i th stit mtix f th stiss st ys. Istd th gdiim fmd s itdditic scdy hs i bth ys. EDS ysis vd tht th scdy hs i bth ys ws gdiim-ich. Vicks michdss tsts cdctd bth ys vd tht th ys w cmsit-ik, with hd, bitt gdiim-ctiig cmd dissd thght sft, m dcti mtix. Th csi sistc f th ys ws dtmid thgh ttidymic dic izti tsts. Tw stis w sd f th csi t tsts:.5 wight ct NC sti d.5 M H 2 SO 4 sti. Th sts fm th mid st ys vd tht i bth th stis, th csi ttis d th csi sistc f th ys icsd with icsig gdiim cctti t 1 wight ct. Th csi t tst sts fm th stiss st ys vd tht th ssivti ct dsity d csi sistc f th ys icsd with icsig gdiim cctti i bth stis. Th xidti sistcs f th mid st d stiss st ys w dtmid thgh th s f Ntzstch Simts Thm Ays. F bth th mid st d th stiss st ys, it ws fd tht th xidti sistc f th ys icsd s th cctti f gdiim icsd wh cmd t th s-civd mid st d stiss st sms. This cd b d t stgy dhig gdiim xid sc tht fmd th sfc f th ys d std i th tcti f th mid st d th stiss st. Kywds gdiim, st, ys, micstcts, mchic tis. Itdcti d jct bjctivs Sts d stiss sts th mst cmmy sd mts cty i th wd. Thy fvd i wid f ictis d t thi tis sch s sb stgth, s f fbicti, d tivy w cst. Mid sts, hwv, cd i my mdi, icdig mst td vimts. Thy s vy ssctib t xidti t high tmts. As st g mt f th mt is st, which is xtmy dsib d csty. Stiss sts d t cd xidiz s siy s diy mid sts. This is d t th fct tht stiss sts cti chmim, which is bst i mid sts. Chmim is ctiv mt which xidizs diy t fm ssiv fim f chmim xid v th sfc f th stiss st cmt. If th ssiv fim is ifm, stb, d sfiig, which is ft th cs, it is b t vid tcti t th stiss st by vtig fth sfc csi xidti. This ss tht th mt s it stct tis its itgity. Ths, stiss sts myd wh bth th tis f st d sistc t csi d xidti qid. Ct dvcs i vis s f mti scic hv d t th discvy tht th dditi f th mts (REM) t i-ctiig cmds, sch s sts d stiss sts, hs cti sitiv ffcts th mchic tis f th mts. Ths icd icsd sistc t ittig csi d dcs i th fti itfc s f th iititi f ittig csi i stiss sts1; fi * Sch f Chmic d Mtgic Egiig, Uivsity f th Witwtsd.. Th Sth Afic Istitt f Miig d Mtgy, 212. SA ISSN X/ civd. 212; visd civd M Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL

2 Ifc f gdiim th micstct d mchic tis f st micstct with fw icsis th sfc f th mt g with ics i th mic-hdss f th mt s w s sigificty icsd csi sistc f th i-ctiig mt2; d th fmti f figid xid which ctibts t sc sticity, ths fvig imvd sc dhc stig i th imvd xidti sistc f th i-ctiig mt3. Ths dvcs i fid f REM dditis t i-ctiig mts d t th iititi f this jct, which tid th yig f gdiim () it tw i-ctiig mts i.. mid st d 316 stiss st. iim is th mt d hs gid ity i th fid f c scic s it hs th highst t-bsbig biity f y mt. Th mt, i th fm f stis f gic gdiim cmxs d gdiim cmds, is s th mst cmmy sd itvs MRI ctst gt i mdic mgtic sc imgig. Hwv, i tms f mtis scic, vy itt sch hs b cdctd i d t dtmi d dstd th ffcts f gdiim dditis th fbicti, micstct, d stt mchic d hysic tis f mid sts, stiss sts, d th stct mtis. Ths, th s f this jct ws t ivstigt th ifc f gdiim dditis th micstct d mchic tis f mid st d stiss st. This t dscibs th imiy sts f tst gmm tht ws dsigd t ssss th bsic chctistics f mid st d 316 stitic stiss st yd with gdiim. Th gmm icdd vti f th imy cssig bhvi, micstct, hdss (bth mic- d mchdss), csi chctistics, d high-tmt xidti bhvi f th gdiim-yd mid st d gdiim-yd stiss st. Th jct bjctivs thf t dtmi th ifc f gdiim th: G micstct Hdss Csi sistc Oxidti sistc f mid st d 316 stiss st. Shd th sts f this tst gmm v sitiv, this jct is itdd t vid fdti f ctid dvmt d qificti f gdiim-yd mid st d stiss st. Litt viw iim d its tis Th mt gdiim () is -dictiv, mtic th mt which is chctizd by its sts sivy whit c d sighty ywish tit4 (Fig 1). Its hysic tis icd mbiity d dctiity. Mbiity is dfid s mti s biity t dfm d cmssiv stss. Dctiity, simi ty, is dfid s sid mti s biity t dfm d tsi stss; this is ft ctgizd by th mti's biity t b sttchd it wi. iim is t sy fd i t s th f mt, istd it is ctid i mis sch s gdit (Fig 1), mzit, d bstsit. It hs mtig it f C, biig it f 3. C d its dsity is 7.87 g/cm3. At m tmt, gdiim cystizs i th hxg, cs-ckd h fm. U htig t C, h gdiim tsfms it th bt fm, which hs bdy-ctd cbic stct. Nty ccig gdiim is cmsd f mixt f six stb ists. Tw f ths ists, 155 d 157, hv xct ct chctistics, which sts i gdiim hvig th highst t, bsbig biity f y mt; hwv, ths ists f gdiim y st ty i w ccttis. As st, gdiim hs vy fst bt t d y hs imitd s s ct d mti f c cts5. iim c s b cmbid with yttim t fm gts tht sd i micwv tchgy. Th mt s hs s scdctiv tis, s wh yd with i, chmim, d th mts it is b t imv thi wkbiity. I-gdiim hs digm A y is sbstc tht hs mtic tis d is cmisd f tw m chmic mts, f which mst b mt6. I th cs f gdiim yd with i, bth sbstcs mtic mts d thy thf b t fm biy y systm. Ays my b hmgs ihmgs. Fm th hs digm f th biy i-gdiim (F-) systm (Fig 2) it c b s tht th tw mts ihmgs, wh yd, s my hss xist. It c s b s tht th tw mts, F d, cmty sb i th iqid stt bt xhibit miim sbiity i th sid stt. Th hs digm shws tht th mtig it f i is C whi tht f gdiim is sighty w t C. Abv th iqids i, th is y sig-hs iqid sti, bw th iqids i sidificti bgis. Th iqids d sids is mt t th mtig its f th tw mts, d fm th sids is it c b s tht ys i this systm v sidify cysts f F, bt wys sid sti mixt f sid stis. Tb I vids dsciti f th imtt its disyd i th F- hs digm. iim-yd micstcts Udstdig th micstcts which sy btid wh gdiim is yd with i-ctiig cmds is vy imtt s ths micstcts, wh sd i cjcti with th F- hs digm, giv Fig 1 () iim mt i its sid stt (b) Th mi gdit 4 31 ARIL 212 VOLUME 112 Th f Th Sth Afic Istitt f Miig d Mtgy

3 Ifc f gdiim th micstct d mchic tis f st Fig 2 F- biy hs digm 7 Tb I Dsciti f imtt its th F- hs digm 7 Rcti Cmsiti Tmt Rcti (t% F) ( C) Ty L δf Mtig δf γf Atic γf αf Atic δf L + γf Mttctic γf + F 17 2 αf itctid βf 17 2 αf ymhic L + γf F itctic L + F 17 2 F itctic L + F 23 6 F itctic L + F 3 F itctic L F αf Etctic L β 1313 Mtig β α 1235 Atic gdiim-yd mid st d gdiim-yd 316 stiss st. This gmm icdd y fbicti, micstct ysis, hdss tstig, csi t tstig, d high-tmt xidti t tstig. Th dti f th tst gmm ws 6 wks. Ay fbicti F th ss f this jct t ys w qid. Fiv f th ys w t hv bs cmsiti f mid st whi th miig fiv ys w t hv bs cmsiti f 316 stiss st. Cmmci sht d t stcks f sizs 3 cm x 3 cm, f bth mid st d 316 stiss st, w vidd. Th gdiim sd ws sid by Adich Chmisty i th fm f gdiim chis which hd 99.9% mt bsis. Th tgt y cmsitis wight ct f bth th mid st/ d 316 stiss st/ ys, vidd i Tb II. Ths sms w th tk t th Mitk btis, wh thy w yd i g-vctd btt c fc. tis f th t s-cst ys w th ct ff sig bsiv ct-ff wh. Ths s-cst sms dwt micstct ysis d hdss tstig. Th miig sctis f th ys w th cd-d dw t 25% f th igi thickss (2 cm) f th y. Rd sms w th ct d ths sms w sd f micstct ysis, hdss tstig, csi t tstig, d high-tmt xidti t tstig. Micstct d chmic ysis Th micstct ysis f th ys ws cdctd thgh th s f ight tic micsc, whi th chmic ysis ws fmd sig EOL SM- 58LV scig ct micsc sig gy-dissiv X-y idicti f which mid st d 316 stiss st gdiim-yd micstcts c b xctd. Th mchic tis f th gdiim mid st d stiss st ys wi dd vy stgy ths stig micstcts d gi sizs. I st sch8, gdiim hs s b ddd t b-chmim-i-ctiig cmds i d t dtmi th sitbiity f ths ys f dvcd t bsbs f st f ictis. Fm th wk d by Smik t.8, it ws fd tht y tc mts f gdiim dissv i th mtix f th b-chmimi-ctiig cmds, whi th mid fmd s gdiim -ich itdditic cstitt with fd itti dissd thght mtix (Fig 3). It ws s fd tht th mt f itdditic cstitt icsd with icsig gdiim cctti. Eximt cd Th tst gmm fwd dig this jct ws dsigd t dtmi th bsic chctistics f Fig 3 Micstcts f b-chmim-i ctiig cmds yd with (A)1 & (B)8 wt% Smik t. 8 Tb II Tgt mid st d stiss st y cmsitis (wt%) Mt C M S Rfc mid st /mid st y ,.5, 1, 2, 5 Mt C M Ni C Rfc 316 SS / SS y ,.5, 1, 2, 5 Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL

4 Ifc f gdiim th micstct d mchic tis f st sctscy (EDS). Ths yss w cdctd i d t dtmi th g micstct d chmic cmsiti f th ys sctivy. Th s-cst ys d sm fm ch f th cd-d ys w htmtd sig c Cfst si d O 41 mtig ss. Th d d s-cst ht-mtd ys w my gd sig 8 git i t big cd i th tmtic gid d ish which gd th ys sig 22, 6, d 12 ts d ishd th sms sig 3 µm d 1 µm ts. Th mid st ys w tchd by ssdig thm i Nit (3 vm ct itic cid (HNO 3 ) d 97 vm ct th) f 5 scds. Th 316 stiss st ys w ctyticy tchd sig tcht which csistd f 4 vm ct itic cid d 6 vm ct distid wt, f 8 scds. A cctig vtg f 2 kv ws sd f th EDS yss. Th K X-y is w sd t ys f F, Ni, C, M, d Si, whi th L is w sd f d M dig th EDS yss. Hdss tsts Th michdss f th sms ws dtmid sig FM-7 Vicks michdss tst with d f 3 gms-fc id f 1 scds. Fiv idttis w md css th sfcs f th sms t dtmi whth ch hs i th micstct f th ys disyd difft hdss. Th mchdss tsts w fmd sig Lc V-1-A2 Vicks hdss tst with d f 5 kg which idtd th sms f 8 scds. Th hdss msmt btid ws vg f t st 5 idttis. Csi t tsts Th csi t tst wk ws cdctd th d ys xct th 5 wight ct gdiim ys, s ths ys dwt sigifict cckig dig th cdig css, which dd thm sitb f th csi tsts. A ttidymic dic izti tst ws fmd th miig ys sig Nv ttistt. Th ys w idividy cctd t stic-istd c wi sig miim t d w th cd-mtd. Th ttidymic dic izti tsts w cdctd t cstt tmt (25 C) t vyig H vs. Ths tw stis with tw difft H vs w qid. Th fist sti sd ws.5 wight ct sdim chid (NC) sti with H f 7.25, d th scd sti ws.5 M shic cid (H 2 SO 4 ) sti with H f.85. Th fc ctd tht ws sd ws Ag/AgC ctd sbmgd i 3 M KC sti, whi th ct-ctd sd ws md f ghit. High-tmt xidti t tsts Th high-tmt xidti t (HTOR) tsts w cdctd i d t dtmi th xidti sistc f th mid st d stiss st ys. F th ss f this tst 1 15 mg f th d ys w ct, cd i mi ccibs, d tstd. HTOR tsts w cid t thgh th s f Ntzsch STA 429 CD Simts Thm Ays (STA). Th STA ws b t cdct thm gvimtic ysis (TGA) f th ys. TGA mss th mss ss/mss gid by th sms s fcti f tmt. Th fc ccib i ch f ths tsts mty, d th sttigs sd f ch tst vidd i Tb III. D t th tim qid t cdct ch tst, it ws dcidd tht y sms f th.5 ct d 2 ct gdiim mid st d 316 stiss sts ys, s w s ct sms f th s-civd mid st d 316 stiss sts, wd dg th HTOR tsts. Eximt sts d discssi Micstct d chmic ysis iim mid st ys Egy dissiv X-y sctscy (EDS) ws t dtmi th v cmsiti f y s w s cdct chmic ysis cizd gis withi y. Ths, EDS yss w cdctd th mid st ys sig vg f 5 its. Fm th EDS ysis f th mid st ys, vidd i Tb IV, it c b s tht th v cmsiti f mst f th mid st ys diffd sighty fm tht f th tgt y gdiim cmsitis. My fcts my hv csd ths disccis, f which my hv b tht th mgificti sd dig th EDS ysis ws t high d thf th its sctd w t sttiv f th wh y. Ath fct my hv b tht sggti my hv ccd i th ys, sic th ys dwt sbsqt ht ttmt d th gis i which gdiim ws t vy ich cd hv b sctd dig th EDS ysis, d ths th disccis s w cty idictis f sggti. Th fi fct my b tht vg f y 5 its w sctd dig th EDS ysis, which my hv b isfficit. Usy 5 1 its shd b sctd wh cdctig v EDS ysis f y, s this wi s tht th cmsiti btid is s sttiv f th y s ssib. Th micstcts btid f th 5 wight ct gdiim mid st y shw i Fig 4. A f th mid st ys micstcts w fd t disy simi micstct t tht f th 5 wight ct gdiim mid st y. Ths micstcts csistd f ight mtix d dk itdditic cstitt dsitd t th gi bdis f th mtix withi ch f th ys. Th itdditic cstitt i ch f th mid st ys, hwv, ws fd t ics s th cctti f gdiim icsd. U cmis f th gdiim mid st ys micstcts, it cd b s Tb III Thmgvimtic ysis tmt sttigs mt V Sttig tmt 2 C Ed tmt 12 C Ht t 1 K/mi (Kvi) Acqisiti t 1 its/mi 312 ARIL 212 VOLUME 112 Th f Th Sth Afic Istitt f Miig d Mtgy

5 Ifc f gdiim th micstct d mchic tis f st Itdditic Cstitt Fit Mtix (A) As- cst 5 wt% mid st Fig 4 htmicghs ( 5x) f th s-cst d d 5 wt% gdiim-yd mid st tht th gi sizs vid thght th micstcts, with sm gis dissd thght g gis. A gifiig ffct ws s bsvd s th cctti f gdiim icsd i th ys. Ths, th gis withi th 5 wight ct y w mch fi d m ifm i siz i cmis t tht f th w cctti gdiim mid st ys. Exmitis f th F- hs digm idictd tht th sbiity f gdiim i i is miim, d thf -ich cmds w xctd t fm. Th EDS ysis f th itdditic cstitt withi th mid st ys, shw i Fig 5, vd tht th dk itdditic cstitt (gi 1) ws fd t b gdiim-ich with mximm gdiim cctti f 27.1 wight ct cdd f th itdditic cstitts withi th 5 wight ct mid st y (Fig 5). Th dissi f th gdiim hs, hwv, ws t ifm; istd, it ws ssy distibtd thght th ys. Th mtix i ch f th ys (gi 2, Fig 5), ctid dissvd gdiim, bt it hd cmsiti simi t tht f fit. (B) Rd 5 wt% mid st Tb IV EDS ysis shwig v cmsiti f th mid st ys (wt %) Ay C M.1 /st /st /st /st /st iim stiss st ys EDS yss w cdctd th stiss st ys sig vg f 5 its. Fm this th v cmsiti f th stiss st ys cd b dtmid (Tb V). Fm th EDS ysis it cd b s tht th v cmsiti f th ys diffd fm tht f th tgt y gdiim cmsitis. Th sm fcts discssd f th mid st ys visy my hv csd ths disccis bsvd. Fth EDS ysis f ch stiss st y (Fig 6) shwd tht th gdiim did t diss ifmy thght th stiss st ys. Istd, th gdiim titid t cti gis thght th ys (gi 2 d 3, Fig 6), fmig s itdditic cstitt thght th mtix f th ys (gi 1, Fig 6). Ths itdtic cstitts w fd by th EDS yss t b gdiim-ich. Fm th gis f th mtix (gi 1, Fig 6) sctd dig th EDS yss, it ws fd tht th mtix f th stiss st ys ctid dissvd gdiim, bt hd cmsiti simi t tht f stit. This is t b xctd wh yig mts with miim sbiity i i ddd t 316 stiss st. F sc cts: 1474 it F F M 5 M F km 64 - kv F sc cts: 1474 it 2 25 F 2 M 15 1 F M F 5 M km 64 - kv Fig 5 EDS ysis f th tw hss withi th 1 wt% gdiim mid st y Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL

6 Ifc f gdiim th micstct d mchic tis f st Th micstcts btid f th 5 wight ct gdiim stiss st y shw i Fig 7. A f th stiss st ys micstcts w fd t disy simi micstct t tht f th 5 wight ct gdiim stiss st y. Th itdditic gdiim-ich cstitts w s t b dsitd t th gi bdis f th stiss st ys, d th mt f itdditic cstitt ws fd t ics s th cctti f gdiim icsd i ch f th ys. Th titiig f th gdiim i th ys cd b csd by th sggti dig cig f th s-cst stiss st ys ft thy hd b fmd i th btt c fc. Hwv, th titiig shd b xctd, isctiv f sggti which my hv tk c, s gdiim disys y miim sbiity i i ccdig t th F- hs digm. f fiv its f ch hs, is vidd i Tb VI. Fm ths sts i c b s tht th mid st ys w cmsit-ik, with hd itdditic cstitt dissd thght sft, dcti fitic mtix. Th bk hdsss f th s-cst d d gdiim mid st ys std i Fig 8. It c b s tht th s-cst.1,.5, 2, d 5 wight ct gdiim-yd mid st sms hd bk hdss bv tht f th s-civd mid st sm (z wight ct gdiim). Th s-cst 1 wight ct gdiim mid st y, hwv, hd bk hdss csidby w th tht f th s-civd mid Hdss tsts iim mid st ys Th michdss tsts cdctd css th sfcs f bth th s-cst d th d mid st ys vd g f hdss thght th sfc f th ys. Ths, it ws c tht th tw cstitts withi th micstct f th y disyd difft hdsss. D t th fct tht gt mt f th itdditic cstitt ws dsitd t th gi bdis f th 5 wight ct mid st y, th hdss f bth th mtix d th itdditic cstitt cd b dtmid. Th hdss f ch hs, tk s vg Tb V EDS ysis shwig v cmsiti f th stiss st ys (wt %) Ay C C Ni M.1 /SS /SS /SS /SS /SS F sc cts: 1258 it M F M C Ni Si M C C M F M F Ni km 8 - O kv F sc cts: 1152 it F M 1 F C C 5 M C F Ni S M Ni Si M C Ni km 8 - O kv Fig 6 EDS ysis f th tw hss withi th 5 wt% gdiim stiss st y Ni Itdditic Cstitt Astit Mtix (A) As-Cst 5 wt% -316 SS (B) Rd 5 wt% -316 SS Fig 7 htmicghs f th d d As-cst 5 wt% gdiim stiss st y 314 ARIL 212 VOLUME 112 Th f Th Sth Afic Istitt f Miig d Mtgy

7 Ifc f gdiim th micstct d mchic tis f st st. Th bk hdss vs f th d gdiim mid st ys w high th tht f th s-civd mid st. Ath ft f Fig 8 is th fct tht th bk hdsss f th d gdiim mid st ys w sigificty high th tht f th s-cst gdiim mid st ys. This ws d t th cd wkig tht tk c dig th ig css, which std i th dfmti f th mid st ys bw thi cystizti tmt. A csqc f th cd-wkig css ws stihdig ffct. This csd th mb f disctis i th ys t ics, which i t std i th stgthig f th ys i.. icsd hdss, whi th sh f th ys ws chgd. It ws fd, hwv, tht th cctti f did t hv ifc f th mt f sti hdig tht tk c. Fm th hdss tds disyd i Fig 8, it cd b s tht th s-cst d d ys xhibitd th sm tds xct f th d 5 wight ct gdiim mid st y. This dviti fm th td ws ttibtd t th ccks tht ccd th sfc f th d y dig th idtti css. Fm th wk d by Qi t.9, it ws fd tht cckd sfcs ffct th hdss vs btid s idttis md cckd sfc g th idttis md cckd sfc. Ths, it c b ssmd tht th ccks th 5 wight ct mid st y ifcd th hdss vs btid ft ch idtti, s th ccks csd th digs f th idttis t b sighty g th thy wd b cckd sfc. Ths g idttis thf std i w hdss msmts btid f th 5 wight ct gdiim mid st ys. Th ss f th hdss tds bsvd f th scst d d mid st ys w ivstigtd. A ssib cs f th icsd hdss f th.1 wight ct mid st y cd b sid-sti stgthig. Hwv, fm th F- hs digm it c b s tht th sbiity f gdiim i i is miim. D t th w cctti f gdiim i th.1 wight ct mid st y, it ws ssib f sm mt f th gdiim t dissv it th fit mtix t sm gis i th y. This cd hv std i sid-sti stgthig f th mtix. If th sbiity f mti is xcdd by ddig t mch yig mt scd hs fms. This ws th cs with th mid st ys, s th sbiity f gdiim i i ws xtmy w. Th ics i th mt f th scd hs which fmd std i th icsd hdss vs bsvd f th 2 d 5 wight ct mid st ys. Th bdis btw th tw hss st i th ys is kw s iths itfc. At this itfc th tmic gmt ws t fct. Ths, th bdy d tmic gmts itfd with si/mvmt f th disctis. This std i th icsd hdss, d is kw s dissi stgthig. Th high hdss f th 5 wight ct mid st y cmd t th 2 wight ct y ws d t th fct tht th 5 wight ct mid st y fmd m f th scd hs. Th icsd hdss f th 2 d 5 wight ct mid st ys, cmd t th th mid st ys, cd s b ttibtd t th m fid gis tht w bsvd i ths ys. A m fid gi stct wi st i imvd mchic tis, f thm big icsd hdss. Tb VI Michdss f th s-cst d d 5 wt% gdiim mid st y hs As-cst 5 wt % Rd 5 wt % mid st (HV) mid st (HV) Itdditic cstitt Mtix Fig 8 Mchdss f th s-cst d d gdiim mid st ys iim stiss st ys Michdss tsts w cdctd css th sfc f bth th d d th s-cst stiss st ys vd tht th difft hss withi th ys xhibit difft hdss vs, with hs big csidby hd th th th. D t th fct tht gt mt f th itdditic cstitt ws dsitd t th gi bdis f th 5 wight ct stiss st y, th hdss f bth th mtix d th itdditic cstitt cd b dtmid. Th hdss f ch hs, tk s vg f fiv its f ch hs, is vidd i Tb VII. Fm ths sts it c b s tht th stiss st ys csistd f hd, bitt gdiim hs dissd thght tivy sft, dcti stitic mtix. Ath bsvti ws th xctd fct tht th michdss f th d ys ws mch gt th tht f th s-cst ys. This ws d t sti-hdig csd dig th cd-ig css. Th bk hdss vs f th s-cst d d gdiim stiss st ys std i Fig 9. It c b s tht th s-cst.5, 1, d 5 wight ct gdiim stiss st ys hd hdss vs bv tht f th fc s-civd stiss st sm. Th s-cst.1 d th 2 wight ct gdiim stiss st ys, hwv, xhibitd hdss vs bw tht f th s-civd stiss st. Th hdss vs f th d gdiim stiss sts ys w Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL

8 Ifc f gdiim th micstct d mchic tis f st sigificty gt th tht f th s-civd stiss st d th s-cst stiss st ys d t th sti hdig tht tk c. Hwv, c gi th cctti f gdiim did t ifc th mt f stihdig. Th d stiss st ys w fd t disy th sm hdss td s th s-cst stiss st ys. Fm th sts i Fig 9 it c b s tht th d stiss st ys disyd icsig td i hdss f th.1 t 1 wight ct gdiim stiss st d ys, whi th bk hdss f th 2 wight ct gdiim stiss st y c gi dcsd. Th y disccy btw th tds f th s-cst d d hdss vs f th stiss st ys ws th bk hdss f th d 5 wight ct stiss st y, which ws mch w th t b xctd. This disccy ws ttibtd t th ccks tht fmd th sfc f th y dig th idtti css, which std i iccty w hdss big btid. Th ss f th hdss tds bsvd f th s-cst d d stiss st ys w ivstigtd, d w fd t b th sm s ths mti f th gdiim mid st ys s discssd i. Csi t tsts iim mid st ys Th csi t f th s-civd mid st i th.5 wight ct sdim chid sti ws.151 mm/ s shw i Fig 1. This ws mch high th th csi ts f th.1 t 1 wight ct gdiim mid st ys. Fm th csi ts tst sts it ws fd tht th csi ts dcsd s th cctti f icsd t 1 wight ct, s s i Fig 1. Fm Fig 1, it c s b s tht th 2 wight ct mid st y xhibitd th highst csi t wh cmd t th th mid st ys, d v high csi t th tht f th s-civd mid st. Th csi t f th 2 wight ct mid st y ws.185 mm/ which ws 18 ct gt th tht f th s-civd mid st. Fm th dic izti cvs f th ys it ws fd tht th csi tti f th mid st ys icsd s th cctti f gdiim icsd t 1 wight ct wh cmd t th scivd mid st, s shw i Fig 11. Th izti cv f th 2 wight ct mid st y vd tht th csi tti f tht y ws th wst cmd t th th mid st ys s w s th s-civd mid st. A m sitiv csi tti css mt t b m thmdymicy stb, thby stig i imvd csi sistc Th csi t f th s-civd mid st i th.5 M shic cid sti ws 11.8 mm/. This ws mch high th tht f th.1 t 2 wight ct gdiim mid st ys. Fm Fig 12 it c b s tht th csi t f th gdiim mid st ys dcsd s th cctti f gdiim icsd t 1 wight ct. U icsig th gdiim cctti t 2 wight ct, th csi t icsd. Hwv, th t f csi f th 2 wight ct y ws sti w th tht f th s-civd mid st sm. Th izti cvs shw i Fig 13 istt th fct tht th mid st ys disyd th sm dic izti td s tht f th s-civd mid st sm wh tstd i th shic cid sti. Th diffcs i th izti cvs idict th csi ttis f ch f th mid st ys d th s-civd mid st. O cmis f th csi ttis it c b s tht th csi ttis f th gdiim mid st ys w t mch gt th tht f th s-civd mid st. Hwv, it is c tht s th cctti f gdiim icsd ( t 1 wt%) th csi tti f th mid st ys icsd sighty. Th 2 wight ct mid st y, hwv, xhibitd th wst csi tti f th ys d th s-civd mid st i th shic cid sti. Tb VII Michdss f th s-cst d d 5 wt% gdiim stiss st y hs As-cst 5 wt % Rd 5 wt % mid st (HV) mid st (HV) Itdditic cstitt Mtix Fig 9 Mchdss f th s-cst d d gdiim stiss st ys Csi Rt (mm/y) wt% iim Fig 1 Csi t f gdiim mid st ys i.5 wt% NC sti 316 ARIL 212 VOLUME 112 Th f Th Sth Afic Istitt f Miig d Mtgy

9 Ifc f gdiim th micstct d mchic tis f st tti vs AG/AgC/3M KCi(V) %, Mid St 1%, Mid St.5%, Mid St.1%, Mid St Mid St 1E-7 1E-6 1E Lg ct dsity (A/cm2) Fig 11 Cmis f izti cvs btid f th gdiim mid st ys i.5 wt% NC sti Csi Rt (mm/y) wt% iim Fig 12 Csi t f gdiim mid st ys i.5 M H2SO4 sti tti vs AG/AgC/3M KC(V) %, Mid St 1%, Mid St.5%, Mid St.1%, Mid St Mid St 1E-7 1E-6 1E Lg ct dsity (A/cm2) Fig 13 Cmis f izti cvs btid f th gdiim mid st ys i.5 M H2SO4 sti Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL

10 Ifc f gdiim th micstct d mchic tis f st Ths, it ws c tht gdiim dditi f t 1 wight ct hd sitiv ffct th csi tti f th mid st ys i bth stis, whi gdiim dditi f t 2 wight ct hd gtiv ffct, d thf dvsy ffctd th csi sistc. Th dcsd csi tti d icsd csi t f th 2 wight ct mid st y d t th ssmti tht gdiim dditi thshd xists btw 1 d 2 wight ct. This thshd, c xcdd, wd st i th gdiim csig dtis tis i th mid st, sch s dcsd csi sistc. Ths dvs sts cd b d t th xcss gdiim, which my hv csd ghit t fm fm th cb st i th mid st. Ghitizti sts i dtis tis i st. It is f this s tht yig mts sy ddd i vy sm tis t mid st i d t vt th st f ghit fmti. Fth tst wk is qid i d t dtmi th gdiim dditi thshd i mid sts, d whth bv this gdiim thshd th gdiim bhvs s ghit-fmig mt. Fm th izti cvs shw i Fig 13 it is c tht th mid st ys did t dg ssivti, ths th cs f th icsd csi sistc i disyd by th mid st ys t 1 wight ct ws ttibtd t th icsd csi ttis btid with icsig gdiim ccttis i bth stis. Ths icsd csi ttis icsd th thmdymic stbiity f th ys. icsig gdiim cctti i.. fm.1 t 2 wight ct gdiim. Ths sts shw tht icsig th gdiim cctti i th stiss st ys std i ics i th csi tti f th y. At high csi ttis mt is sid t b m thmdymicy stb. Ths, th gdiim dditis csd th stiss st t b m thmdymicy stb, d this stbiity icsd with icsig gdiim cctti. Simiy it ws shw tht th csi ts f th ys dcsd s th cctti f gdiim icsd. Icsig gdiim dditis st i ssivti f th stiss st, d this is th cs f th icsd csi sistc. This cd b d t y f gdiim xid which my hv fmd th sfc f th ys. Th ssiv y is ssmd t b gdiim xid, s gdiim xid hs th mst gtiv thy f fmti wh cmd t th xids tht cd fm i th stiss st ys, icdig chmim xid. iim is thf th mst ctiv mt d th mst iky t xidiz fist. Sic th csi t f th scivd stiss st ws high th tht f th stiss st ys, this sggst tht gdiim xid, cmbiti f gdiim d chmim xid, is m ffctiv i tctig th stiss st fm csi th th chmim xid y tht fmd th s-civd stiss st. Ath ccsi tht cd b dw fm th sdim chid csi t tsts th stiss st iim stiss st ys Th csi ts f ch stiss st y i th.5 wight ct sdim chid sti std i Fig 14. It c b s tht th csi t f th scivd stiss st i th sdim chid sti ws.54 mm/. It c s b s tht th csi ts f th stiss st ys dcsd s th gdiim cctti icsd fm.1 wight ct t 2 wight ct gdiim, with mch w csi t big bsvd t 2 wight ct cmd t th s-civd stiss st. Simi csi t sts w fd f th gdiim stiss st ys i th.5 M shic cid sti, s shw i Fig 15. It c b s tht th csi t f th s-civd stiss st i th shic cid sti ws.42 mm/, which is high th tht f th.1 t 2 wight ct stiss st ys. Th izti cvs f th stiss st ys i bth stis (Fig 16 d Fig 17) idict tht th stiss st ys xhibitd w ssivti ct dsity th tht f th s-civd stiss st i th sdim chid sti. Th sigificc f w ssivti ct dsity is tht th ys w b t ssivt t w ct dsity th th stiss st. Thf, thy w b t fm tctiv y mch s th -yd 316 stiss st. Th sts s shw tht th gdiim stiss st ys xhibitd high csi tti th tht f th s-civd stiss st wh tstd i bth stis. A th stiss st ys disyd icsig csi ttis with Csi Rt (mm/y) Fig 14 Csi t f gdiim stiss st ys i.5 wt% NC sti Csi Rt (mm/y) e wt% iim wt% iim Fig 15 Csi t f gdiim stiss st ys i.5 M H2SO4 sti 318 ARIL 212 VOLUME 112 Th f Th Sth Afic Istitt f Miig d Mtgy

11 Ifc f gdiim th micstct d mchic tis f st tti vs AG/AgC/3M KC(V) %, 316 Stiss St Stiss St 1%, 316 Stiss St.5%, 316 Stiss St.1%, 316 Stiss St 1E-8 1E-7 1E-6 1E Lg ct dsity (A/cm2) Fig 16 Cmis f izti cvs btid f th gdiim stiss st ys i.5 wt% NC sti % 316 Stiss St 1% 316 Stiss St.1%, Stiss St.5%, Stiss St Stiss St - 1M H2S tti vs AG/AgC/3M KC(V) E-11 1E-1 1E-9 1E-8 1E-7 1E-6 1E Lg ct dsity (A/cm2) Fig 17 Cmis f izti cvs btid f th gdiim stiss st ys i.5 M H2SO4 sti ys is tht th gdiim gdiim/chmim xid ys fmd w ifm, ctis, tcis, d sfiig. This is std by th fct tht, thgh th ys dwt ssivti, thy did t disy y ittig csi, which mt tht th ssiv xid fim did t bk dw i ith f th stis. High-tmt xidti t tsts iim mid st ys Thm gvimtic yss (TGA) w cdctd th ys d th s-civd mid st sm i d t dtmi th chg i mss s fcti f tmt. Th sts fm th TGA isttd i Fig 18. It c b s tht th s-civd mid st sm dwt sigifict mt f xidti ft tmt f 8 C ws xcdd. Oc th mximm tmt f th STA tst ws chd (12 C) th tt mss ics f th mid st sm ws fd t b 9.17 ct. Hwv, bth th gdiim mid st ys did t dg sigifict mt f xidti, v c th mximm tmt f th STA tst ws chd. Th.5 wight ct, mid st y xicd tt mss ics f.55 ct whi th 2 wight ct y xicd tt mss ics f.51 ct. Fm th sts btid fm th TGA ysis f th mid st ys, it is c tht gdiim dditis t th mid st std i dcs i th mt f xidti. Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL

12 Ifc f gdiim th micstct d mchic tis f st TG/% 11 [1] mid st [2] mid st_.5 18 [3] mid st_2% [1] 16 Mss Chg: 9.17% Mss Chg: -.16% Mss Chg: -.37% Mss Chg: -.74% Mss Chg:.55% Mss Chg:.51% 1 [2] [3] Tmt/ C Fig 18 Mss chg vs. tmt f th mid st ys TG/% 12 Mss Chg: -.65% Mss Chg: 23% 11 Mss Chg: -.93% Mss Chg:.2% 1 Mss Chg: -1.64% Mss Chg: -.41% [1] 99 [2] 98 [3] 97 [1] Stiss st [2] Stiss st_.5 96 [3] Stiss st_ Tmt/ C Fig 19 Mss chg vs. tmt f th stiss st ys It is s c tht th xidti sistc f th mid st icsd with icsig gdiim ccttis. This is ssmd t b d t th fmti f gdiim xid th sfc f th mid st. iim xid hs th mst gtiv ht f fmti f th mts st i th mid st, d s st is vy ctiv. This ctivity csd th gdiim t xidiz mch fst th y f th th mts st. Smt t.3 fd tht th mt dditis t i-ctiig cmds std i th fmti f fi-gid xid, which ctibtd t sc sticity ths fvig imvd sc dhc. Ths, it is ssmd tht if gdiim xid ws fmd, it wd fm s stgy dhig sc th sfc f th mid st, d this wd xi th sigifict xidti sistc xhibitd by th mid st ys. Oc th gdiim xid sc ws fmd, it wd cd t gw t vy sw t,1 thf it wd t tt it th mid st. It is ssmd tht s th cctti f gdiim icsd th mt f xid sc fmd icsd, thf, th dyig mid st wd b btt tctd, d this std i th icsd xidti sistc xhibitd by th 2 wight ct mid st y cmd t th.5 wight ct mid st y. iim stiss st ys Th sts fm th TGA th gdiim stiss st ys isttd i Fig 19. It c b s tht th stiss st sm did t dg sigifict mt f xidti. Th tt chg i mss f th stiss st 32 ARIL 212 VOLUME 112 Th f Th Sth Afic Istitt f Miig d Mtgy

13 Ifc f gdiim th micstct d mchic tis f st sm cmti f th STA tst ws.23 ct. Bth th gdiim stiss st ys xicd v w chg i mss cmti f th STA tst. Th.5 wight ct stiss st y xicd mss chg f.2 ct, whi th 2 wight ct stiss st y xicd mss chg f.41 ct (mss ss). Fm ths sts it c b ccdd tht gdiim dditis t stiss st std i dcs i th mt f xidti xicd by th stiss st. It is s c tht th xidti sistc f th stiss st icsd with icsig gdiim cctti. Th s f th ics i th xidti sistc f th stiss st ws ssmd t b th fmti f gdiim xid th sfc f th stiss st, s i th cs f th gdiim mid st y. Ccsi Th bjctivs f this jct w mt, s it ws fd tht gdiim dditis t bth mid st d 316 stiss st hcd th mchic tis i tms f imvd hdss, imvd csi sistc, d imvd xidti sistc. Th g micstcts f th mid st d stiss st ys tht w btid disyd gdiim-ich itdditic cstitt with fd itti dissd thght th ys. Th ys hd micstct which ws cmsit-ik. Sic th sts f this jct hv vd t b sitiv, thy itdd t sv s fdti f th fth dvmt f th gdiim mid st d stiss st ys. 7. Th xid y fmd th mid st d stiss st dig th high-tmt xidti t tsts shd b ysd i d t dtmi whth th y csists f y gdiim xid cmbiti f xids 8. Th ssiv y fmd th stiss st ys dig th dic izti tsts shd dg chmic ysis i d t dtmi whth th y csists f y gdiim xid cmbiti f xids. Ackwdgmts 1. sis v d Mw, Lct d jct Svis, Uivsity f th Witwtsd. 2. D Ntsh Scks, Uivsity f th Witwtsd. 3. By Nwi, Uivsity f th Witwtsd. 4. Shm Bd, Uivsity f th Witwtsd. 5. Asimy Kit. Advcd Mtis Divisi, Mitk. Rfcs 1. KIM, S. EON, S., LEE, I., d ARK, Y. Effcts f th mts dditi th sistc t ittig csi f s dx stiss st t 1. Csi Scic, v. 52,. 6, WANGA, K.-L., ZHUB, Y.-M., ZHANGA, Q.-B., d SUN, M.-L. Effct f th cim th micstct d csi sistc f s cddd y ctigs. f Mtis cssig Tchgy, v. 63,. 1 3, y Rcmmdtis 1. Th ffct f ig th tchig css shd b ivstigtd fth, g with ivstigti t dtmi m sitb tchts tht cd b sd f th gdiim mid st ys 2. Th sm tst gmm s tht fwd i this jct shd b cdctd s-cst ys which sbjctd t ht-ig which hv dg sbsqt ht ttmts i d t hmgiz th stct f th ys 3. Chctizti f th siz, distibti, d idtity f th gdiim-ctiig hss shd b cdctd, s ths fcts y dfiig i th mchic tis f th ys 4. Ays with cs icmts f gdiim ccttis shd b fbictd d tstd i d t dtmi th gdiim dditi thshds f th ys 5. Fth EDS yss, t st 1 its, shd b cdctd i d t dtmi th xct cmsiti f th ys. If th ct cmsitis sti diff fm tht f th tgt cmsitis, c shd b tk i th fbicti stg i d t s th cct mts f gdiim ddd t th s-civd mid st d stiss st 6. Th th mchic tis f th mid st d stiss st ys i.. tsi d imct stgth shd b ivstigtd 3. SAMANTA,S.K., MITRA, S.K., d AL, T.K. Effct f th mts micstct d xidti bhvi i TIG wdmts f AISI 316L stiss st. Mtis Scic d Egiig, v. 43,. 1 2, 25 Agst htt:// st ccssd 7/8/ htt:// st ccssd 7/8/ AVNER, S.H. Itdcti t hysic Mtgy McGw Hi, Nw Yk ZHANG, W., LI, C., SU, X., d HART, K. A dtd vti f th F- systm. f hs Eqiibi, v. 19,. 1, SMOLIK, G.R., BRANAGAN, D.., d SHABER, E.L. Advcd Nt Absbs F St F Aictis. Idh Nti Egiig d Evimt Lbty, Idh Fs, Idh, 26 Agst QUINN, G.D., GREEN,., d XU, K. Cckig d th idtti siz ffct f K hdss. f th Amic Cmic Scity, v. 86,. 3, IEKOSZEWSKI,., WALISA, L., BARLAK, M., STAROSTAA, W., OCHRYBNIAK, C., d BOCHENSKA, K. Aft Oxidti i 1±C, j, Eb, Mq, 29. Th f Th Sth Afic Istitt f Miig d Mtgy VOLUME 112 ARIL