NGHIEN cuu-TRAODOI NGHIEN CirU TUONG TAG G I O A NHOM VA HOP KIM NHOM VOI THEP KHI HAN (*) Th.S NCS LLTONG VAN TIEN PGS TS HA MINH HUNG (**) Th.S NGUYEN VAN NAM TOM TAT Bai bao trinh bay cosdly thuyet vetUcfng tac glQa nhom va hdp kim nhom vdi thep, dong hpc hinh cac pha lien kim loai he Fe-AI qua trinh khuechtan han, lam luan cu" khoa hoc cho viec nghien cuTu u'ng dung cong nghe han no tao phoi vat lieu hpp kim I6p (trimetal) thep - nhom - hpp kim nhom, dam bao chat lUpng cao sCr dung ky thuat hien dai nhu": che tao cac cong trinh cong nghiep sieu nhe, vat lieu trung gian de han ket cau cong nghiep dong tau bien va kythuat hang khong Cac thong so nhiet dpng phan anh su" phat trien Idn len cua chieu day I6p lien kim loai hinh bien gl6i2 Idp vat lieu thep-nhom, thep-hpp kim nhom lacPsdkhoa hpc cho viec xac djnh che dp nhiet han phij hpp suf dung chi tiet trung gian Idp ban ket cau giOfa thep va hpp kim nhom dp ben cao dd cd Viet Nam la nude nhap khau thiet hi may mdc tir nhieu nguon khac DAT VAN DE Van de cap thiet nhat hien ky thuat cdng nghe hien dai la phai giam thieu Idioi lupng ket cau kim loai ciia may mdc thiet hi, dong thdi, tang cac dac tinh ky thuat va dp ben lau dieu kien lam viec thuc te cua chiing Dieu dd dan tdi su can thiet phai su dung nhieu loai vat lieu to hpp thep - hpp kim mau khac khdng phai tren toan bd chi tiet hoac ket cau ma chi mot phan ciia chiing true tiep chiu tac ddng cua tai trpng, nhiet dp, mdi tmdng lam viec nhat dinh.Vi the, cac loai vat lieu ket cau bimetal thep - nhdm (thep hpp kim nhdm) dang cang dupc ling dung rpng rai va thiic day sy phat trien cac nganh che tao ten Ilia, may bay, d td, ddng tau bien va mot so nganh cdng nghiep trpng diem cua nen kinh te tren the gidi, (*) Vi?n Nghien cuu Co (**) Tniong D ^ hpc Sao Do Trong cdng nghiep ddng tau bien noi rieng, vat lieu bimetal thep - hpp kim nhdm dupc dung che tao phan noi tren boong tau va npi that ben tau Trong cdng nghiep hda chat, cac bon chiia bang hpp kim nhdm dupc hpc bdi thep Ididng gi, cung nhu cac dudng ong noi giua cac binh chiia hda Idng Trong ky thuat hat nhan, ngudi ta che tao cac chi tiet noi cho he thong ong dan, cdn cac ten liia - lien ket giiia cac ong nhdm vdi ong thep Ididng gi ben nhiet he thong dudng ong dan bang nhdm [1] Han nhdm va hpp kim nhdm vdi cac kim loai khac la cdng nghe tuong doi mdi, rat khd thuc hien bdi cd nhieu hien tupng phiic tap va da dang xay tren bien gidi lien ket kim loai giiia chiing, mac dii nhdm cd hang loat uu diem ve cac tinh chat co - ly dam bao cho nd dupc su dung bien cdng nghiep nhu: khoi lupng rieng thap, dp dan dien cao, dp ben co hpc cr- TAP CHI c a K H I VIET NAM V So 7-Thang7 nam2011 NGHIEN cuu-TRAODOI Trd ngai Idn nhat viec tao lien ket kim loai giiia nhdm va hpp kim nhdm vdi thep chinh la tuong tac hda hpc giiia cac kim loai dd, dan tdi hinh cac lien kim loai tren dudng bien gidi lien ket lop ma khdng cd phan ling ngupc lai Dac diem khac biet niia Dac biet la d nhung dieu kien lam viec khSc nghiet ciia sir tuong tac giua nhdm vdi thep ban la thi viec tao vat lieu bimetal thep Ididng gi - hpp kim van de gia cdng nhiet moi ban tiep theo khdng the nhdm la van de quan trpng hang dau dupc chii trpng dat dupc can bang nong dp tren bien gidi lien ket lap nghien ciiu phat trien d nhieu nude cdng nghiep phat (giong nhu doi vdi cac bon ban cac mac thep khac trien tren the gidi nhu: Vien ban Patdn va Vien Vat ly Ky nhau) Su tap trung cua cac pha lien kim loai d dang thuat thudc Vien Han lam Khoa hpc Ucraina (Ucraina); cuoi ket tinh van dupc bao toan va ling xii tiep theo ciia Vien cac van de vat lieu thudc Vien Han lam Khoa hpc mdi ban dupc xac dinh bdi so lupng, hinh dang, dac Nga, Vien Luyen kim den Uran, Vien hpp kim Mau tinh phan bd va cac tinh chat cua Idp mang mdng lien va Vien Luyen kim mang ten A A Baikov (Lien bang kim loai Nga); Trung tam NASA (My) va cac td chiic khoa hoc Nhu vay, qua trinh ban ndng chay (doi idii cdng nghe ciia Anh, Phap, Diic, Nhat Ban [1,3] ca ban ap luc) lien ket giiia nhdm vdi thep thudng co Vi the, viec he thong hda mot so ket qua nghien phan: sat (thep), cac mang mdng lien kim loai ciiu ly thuyet va thuc nghiem ve eo che va ddng hpc sat - nhdm va nhdm (hoac hpp kim nhdm) Tinh chat qua trinh hinh lien ket kim loai giiia hpp kim cua vat lieu Idp mang mdng lien kim loai phan bd giiia nhdm vdi thep tren co sd tai lieu tham khao cap nhat Fe va Al cd su tuong tac giua chiing da dupe nghien dupc nham lua chpn cdng nghe thich hpp va gidi ban ciiu ky cdng trinh [1] muc tieu nghien ciiu cua de tai luan an tien si ky thuat theo hudng ling dung nang lupng no de che tao vat lieu Phan tich nhieu so lieu thuc nghiem nhan dupc to hpp Idp (trimetal) thep - nhdm - hpp kim nhdm thu nghiem xac dinh dp ben bam dinh Idp thep - nhom lam chi tiet trung gian sii dung cdng nghiep ddng (hpp kim nhdm) va lien he vdi cau tnic te vi bien gidi mdi va sua chiia tau bien d Viet Nam la rat can thiet va moi ban cdng trinh [2] cho thay: moi ban giiia cd y nghia khoa hoc nhat dinh thep va nhdm cd dp ben cang cao neu nhu chieu day lop mang mdng lien kim loai cang nhd (dudi 10 pm) dam bao, dp ben chong gi cao , vi the, ban vdi thep, se giam khdi lupng chi tiet ket cau dot bien, cdn ban vdi ddng thi lam giam kim loai quy hiem Cu rat dang ke NGHIEN CUtJ CO SOf LY THUYET VE TlTONG TAC CUA NHOM v O l THE? Viec tao moi lien ket kim loai giiia nhdm vdi thep tren thuc te la rat Idid khan vi cd su khac xa ve nhiet dp ndng chay cua chiing (nhdm ndng chay va trd pha Idng tmdc thep kip dupc nung ndng can thiet); sai khac Idn ve he so gian nd nhiet, he so dan nhiet va nhiet dung rieng cua cac kim loai phan hpp kim va dieu dd tao dieu kien cho hinh ling suat nhiet; su cd mat ciia mang dxit khd ndng chay lam cho hinh cac tap chat mdi ban De hda tan mang dxit ngudi ta phai su dung thuoe ban nhdm dac biet, vi thuoc ban binh thudng de ndng chay, khd tham udt be mat moi han tren thep, nen chiing khdng sii dung de ban cac mac thep khac dupc Cac loai thuoc ban dd phan ling vdi nhdm ndng chay va lam pha hu\ dot bien phan cua nd, ket qua la chiing khdng su dung true tiep de ban thep vdi nhdm dupc TAP C H i c a KHi VIET NAM V Tir cac nghien eiiu ly thuyet ve gian trang thai, nhdm va sat tao cac dung dich rSn, cac lien kim loai va cung tich Dp hda tan cua sat nhdm d pha rii la rat nhd (0,053 % d nhiet dp ciing tich 654 °C), dp hoa tan cua nhdm sat khoang gan 600 lan Idn hon va bang 32 % Khi ket tinh lai to chiic hpp kim nhom vdi sit ca ham lupng sk dupc dua vao khong Idn ciing da xuat hien lien kim loai FeAlj (59,18 %A1) Vdi ham lupng dudi 1,8 % Fe va d nhiet dp 654 °C hinh to chiic cung tinh Al + FeAlj Tiep tuc tang ham lupng % Fe hpp kim se xuat hien lien ket hda hpc vdi cac phan sau: FCjAl, (62,93 % Al); Fe,Alj (54,71 % Al); FeAl^ (49,3 % Al); FeAl (32,57 % Al), ta thay rang, he Al - Fe cd mot lupng khdng Idn cac pha, nhung mot so cac pha co phan tuong doi phiic tap nen can nghien ciiu i^y moi lien he cd tinh chat di tmyen giua to chiic cua tat ca cac pha he Cac phan he Al - Fe cd cau tnic don gian nhat la: a-Fe (mang tinh the lap phuong the tam vdi a = 2,8664 A); y -Fe (mang tinh the lap phuang So 7-Thang nam 2011 NGHIEN cuu-TRAODOI dien tam, a = 3,656 A); Al (mang tinh the lap phuong dien tam vdi a = 4,04914 A) chiing chuyen tir cau tnic sang cau tnic khac thay ddi ty le cac phan Ddng thdi, khdng cd Tuy chiing cd cac gia tri thdng so mang gan b5ng mot cau tnic nao ciia lien kim he Al - Fe (FeAl^, (a^, Idn hon a^^^ chi 10,7 %), eac phan tir Fe^Aljj, Fe^Alj) khdng phai la dang cau tnic thii cap nhung cau tnic khdng tao day lien tuc cac dung cua Al hoac Fe (sieu cau tnic, to ehiic bien dang thii dich rki Tren cau tnic pha a-Fe dua tren mot day ban cap, cau tnic xam nhap), tiic la khdng the tach che cua cac dung dich rk\ vdi ham lupng Al toi da bSng tir chung bang each dich chuyen hoac thay the eac khoang 53 %-nguyen tu d nhiet dp 1103 °C Tir dung nguyen tir rieng biet hoac cac nhdm nguyen tu Neu dich ran nay, ket qua cua bien doi pha tir phan bo cd cau tnic cua cac lien kim FeAlg va Fe^Al^^ eon trat tu cac nguyen tu Fe va Al, tao hpp chat giau giii dupc dii chi mot lupng nhd cac vimg tir td chiic sit nhat: FeAl va FCjAl vdi cau tnic FeAl la mang tinh ciia nhdm, thi td chiic cua Fe^Al khdng tdn tai the lap phuong giong nhu CsCl, a = 2,903 A; cdn ¥e^A\ nhiing viing cau tnic la mang tinh the lap phuong dien tam vdi a = 5,78 A Ve nguyen ly, tuong tac cua cac dung dich Trong viing cd ham lupng Al khdng cao cua he Al - Fe nhdm ndng chay vdi sat d dieu kien ban tren bien gidi se hinh pha khdng on dinh Fe^Al vdi cau tnic tinh Idp quan sat thay chi loai lien kim he Al the mang luc lang cd dang MgZn^ (pha Lavec) vdi kich Fe: FeAlj va Fe^Al^, vi the ma cac tinh chat ciia chiing thudc mang: a = 4,76 A; c = 7,7 A; a/e = 1,62 Vdi ham dupe nghien eiiu rat can trpng Dp ciing te vi cua pha lupng nhdm Idn hon 50% nguyen tu Al he Al - Fe Fe^Alj, FeAlj va FeAl., dao ddng khoang 9600 thi cd cac lien kim FeAl^, Fe^Al,, FeAlj (Fe^Aljj) va pha -^11500 MPa Khi nhiet dp tang, dp ciing te vi cae lien gia on dinh FeAlg Cau tnic eac lien kim Fe.,My Fe^Aljj kim giam, ddi vdi pha FeAlj va FeAl, hien tupng bd va Fe Alg da dupc ma hda [ ] bien cimg bat dau tir 0,45T^^ Cac lien kim FeAlj va Tac gia cdng trinh [1] cho rang: giiia cac phan cac lien kim cuoi cung va phan cac lien kim khac dupc khao sat to chiic te vi (FeAl, FCjAl) cd mot khoang ngat quang (khdng lien tuc), nen tot nhat la tien hanh nghien ciiu cau tnic cac lien kim FeAlg, Fe^Alj^ va FCjAlj moi tuong quan vdi cau tnic tinh the cua Al bang each xac lap ty so giiia hai cau tnic tinh the cua Al va lien kim gan vdi nd (FeAlg) Dau tien, phai khang dinh rang hai mang cau tnic tinh the khdng cd gi giong nhau: mang tinh the ciia FdAlg la hinh luc lang vdi chu ky mang a = 7,44 A ; b = 6,4644 A; c = 8,779 A Trong mang cau tnic tinh the nay, cac vung to chiic Al, mac dii bien dang cua phan to khoi bat dien, ty le giua cac kich thudc meoig cua nd la khdng the bieu thi dupc bang eac tri so don gian (khac vdi cau tnic cua nhdm Al) Cau tnic cua lien kim Fe^Al^^ (FeAlj) la mot cac cau tnic phiic tap cua lien kim loai cd phan to mang tinh the don hudng vdi chu ky a = 15,489 A; b = 8,0834 A; c = 12,476 A; (3 = 107°43' Cau tnic ciia lien kim loai FCjAlj cd ham lupng Fe giau hon, so vdi lien kim Fe^A],3 la hinh luc lang vdi chu ky mang a = 7,68 A; b = 6,4 A; c = 4,2 A Fe,Alj cd trd khang chong bien dang tiic thdi thap (15 -^ 17 MPa), cdn lien kim Fe^Al^ - cd he so khuech tan Idn nhat va cd dien trd anomal cao nhat Vi the, eac dd thi nhan dupc bieu thi su phu thudc cua cac he so gian nd nhiet eiia hpp kim da lam rd sir khac biet dot bien ve cac tri so cua he so gian ,^ nd nhiet hpp kim va cac kim loai co ban (Al va Fe) Lay vi du pha Fe,Alj cho thay lien ket hda hoc Al Fe hinh moi ban rat gidn va cd xu hudng tang the tich cua cae tinh the va tien tdi su pha buy moi ban [1,2] Bang thuc nghiem ngudi ta da xac dinh dupc cac dac tinh ben nen va nghien cim tinh chat hda hpc ciia lien kim loai mot so dung dich ran Khi nhiet dp tang dp Cling te vi ciia cac lien kim giam Nghien ciiu cac quy luat chu yeu ve su hinh Idp mang lien kim loai qua trinh ban, kha nang tac ddng den td ehiic va tinh chat cua nd, xac dinh tinh chat cua cac vat lieu to hpp kim loai dam bao dieu kien lam viec khac nghiet nhat qua trinh sir dung la cd y nghia rat Idn De dieu khien qua trinh ban thep vdi nhdm, can cd nhiing thdng tin ve quy luat hinh cac lop mang Phan tich cau tnic cac lien kim ndi tren cua he Al lien kim loai tren bien gidi Idp Co che va ddng hpc - Fe, giau Al, cho thay, cac cau tnic tinh the dd mac tuong tac ciia nhdm vdi sat da dupc nghien ciiu ban dii khac xa nhau, nhung lai giong ve ban chat, cac kim loai khdng ndng cha> (trang thai ran), Idii chicr= TAP CHI c a KHI VIET NAM V So 7-Thang nam2011 NGHIEN cuu-TRAODOI CO nhdm ndng chay (trang thai rin - Idng) va ca Al va thep (Fe) cimg ndng chay (trang thai long) Sau day ta hay nghien ciiu su hinh va phat trien cua cac pha lien kim loai ban d trang thai ran: Doi vdi cac moi han thep - nhdm quan trpng nhat la cae giai doan dau cua qua trinh, khdng cd mot be mat lien tuc cac lien kim loai tren bien gidi lien ket kim loai khac lam giam co tinh vat lieu Tac gia cac cdng trinh [1,2] bang md hinh hda vat ly tren cac mau bimetal da nghien ciiu dac tinh thay doi cau tnic va dp ben lien ket kim loai giiia Al va thep (Fe) phu thudc vao cac yeu td nhiet va thdi gian Cac quy luat ddng hpc phat trien Idp mang trung gian hinh tren bien gidi lien ket vat lieu bimetal nhdm A6 - sat armko nung ndng vimg nhiet dp 550 -^ 700°C dupc thuc hien tren mau lay tir bang bimetal can dinh tren may can cdng nghiep true D700 vdi miic bien dang deo lan la e =; 60%, u khoang 560 ^ 700 °C vdi thdi gian giii nhiet t = 0,4 - 4,0 gid Id thi nghiem va kiem dinh cau tnic bang each lam ngudi nude hoac khdng Ket qua nghien ciiu khao sat cau tnic te vi vat lieu bimetal nhdm A6 Fe (sat armko) cho thay: sau ii d nhiet dp ket tinh lai sat armko tren bien gidi Idp xuat hien mot lop mang trung gian lien tuc d cac mau ban dau cd lien ket kim loai giiia Idp deu va tin cay vdi dp ben bam dinh Idp ban dau la 30 - 50 MPa Mot so mau liic dau cd dp ben bam dinh lop thap hon cd Idp trung gian hinh d dang cac doan cue bd tren bien gidi tai nhiing noi cd lien ket kim loai giiia Idp deu, kin Neu ii mau bimetal bang Id cao tan vdi thdi gian nung Ididng Idn hon -^ 10 s thi phat hien thay Idp trung gian xuat hien dong thdi cimg liic vdi su hinh cua cac doan ket tinh lai dau tien tren nen thep Cimg vdi su gia tang cua nhiet dp va thdi gian giii nhiet u chieu day Idp trung gian tang len mot each dot bien Tren hinh la to chiic te vi dien hinh cua Idp mang tmng gian tren bien gidi lien ket kim loai giiia Al va Fe Ldp tmng gian cd hinh dang keo dai theo hudng tien vao nen thep, hien rd sau tam thuc mau dung dich (47 mg HNO, + 50 mg HCl + mg HF) va giong nhu cac doan cau tnic tinh the dang tru Theo sir phan bo cua cac bloc, ngudi ta da xac dinh ring, su phan bo lai cac tinh the chi quan sat dupc tren cac mau mai theo hudng vudng gdc vdi mat lien ket giiia ldp „ Al -Fe ban dau Hien tupng khdng quan sat thay tren cac mau mai ngang hudng khao sat ndi tren Nhu vay, dinh hudng khuech tan va ldp tmng gian duac hinh cd cau tnic testua nhat dinh Nhd phuong phap phan tich ronghen cau tnic va ronghen-quang pho, ngudi ta da xac dinh ring ldp tmng gian duac cau tir cac lien kim loai Fe^Al^, cd ludi tinh the kieu true giao vdi chu ky mang a = 7,66 kX, b = 6,39kX, c = 4,19kX 'v ,'TJ^«'_ Hinh :T6 chuc te vi voi eac doan tinh the dang tru phan bo doc theo huong khuech tan [ ], x 440 14/^'j K c—:— § ) 4Ka_ rr^- - i 8' ^ ? 1! '^,2 m lift 11,4 1(1,2 m ^ ii,o i'ld* a) b) Hinh 2: Su phu thupc nhiet - thoi gian cua toe dp ion len ciia lop hen kim loai bimetal sat armko - nhom A6 (a) va sat-armko - hop kim nhom ACM (b) [1] Cac doan tinh the dang tru hinh qua trinh khuech tan cd dang keo dai dpc theo true c cua phan td va dinh hudng cho mat phing co so vudng gdc vdi hudng khuech tan Dac diem la CO sd de cho ring cap vat lieu khao sat (Al So 7-Thang nam 2011 NGHIEN cuu-TRAODOI Fe) nung ndng cd su khuech tan dinh hudng cua nhdm vao sit di qua pha trang gian dupc hinh d thdi diem dau tien ban nhdm vdi thep [1] Khi dd, thdi gian dt can thiet cho su hinh ldp mang trang gian cd chieu day dy se bing tong thdi gian cua giai doan tich tu cac nguyen tir vdi so lupng can thiet cho su hinh cac mam pha mdi va thdi gian khuech tan cua cac nguyen tii nhdm tdi mat bien gidi phan ling: be mat lien ket ldp kim loai ban; d - bing so toe dp phan ung tren bien gidi A^B^ | B; I - ddng cac hat nguyen to A tien tdi be mat lien ket ldp; M^ - the tich mdn cua nguyen to B Neu cho ring qua trinh khuech tan la on dinh dang hudng, thi ddng,I viing be mat lien ket ldp se bang toe dp phan ling tren be mat dd: (6) v/ / =A:A =d.(c -c) =d.Ac:I =D (c„-cj/y y y' y Tir dd ta cd: (1/M^ (d/dt) (\) dt = dy/K^ + y.dy/K^ y^ y / y / y ^ o / -^ (7) Ac^ =D.Ac/ (yd^, + D);A = Trong do: K, - tri so ty le thuan vdi he so khuech Tir (6), (7) ta cd: (8) 1/M^ - dy/dt = d^.Ac / tan Al qua mang trung gian; K^ - bing so toe dp tuong (y.d^ + D) tac hda hpc cua cac nguyen tir Al va Fe tren be mat phan Tich phan bieu thiic (8) va tinh den dieu kien ban ling tai bien gidi ldp dau, ta cd: Lay tich phan bieu thiic (1) va chu y ring t = (9) j ; ^ ^ = - D/dy ± [(D/dyp + 2M^ Ac.D.tf va y = thi hang so tich phan cung bing 0, ta cd cdng thiic tinh chieu day ldp mang trung gian sau: Tir bieu thiic (9): (10) D = (f/t)/(2M^ Ac.D.t), tiic (2)y = K/K^ + [(K/K/ + 2K^.tr Toe dp tuong tac hda hpc K ^ » Kj, vi the, cd the coi nhu gan diing rang su Idn len cua ldp mang trang gian cimg vdi su gia tang cua thdi gian giu nhiet xay theo quy luat ham phi tuyen: (3)y^^2K,t Trong bieu thiic (3) he so toe dp phat trien cua ldp mang mdng K = 2Kj, phu thudc vao nhiet dp theo quy luat ham so mii: (4)K = K^exp(-Q/RT) Giiia he so toe dp Idn len cua ldp mang trung gian va he so khuech tan cd moi quan he: i5)D=f.K;f=(c^ + cJ/4.(c^-cJ d day: c,, c^ - he so khuech tan eiia nguyen to kim loai tren bien gidi cd pha trung gian Tir bieu thiic (5) ta thay: de xac dinh dupc he so khuech tan thuc theo cac gia tri da biet cua K can phai xac dinh diing c, va c, He s / c d the nhan dupc bdi bieu thuc, dd gia tri can tim Ac dupc xac dinh theo gian trang thai can bang De lam dupc dieu dd ta hay xem xet he A(A^BJ B Dua vao cac ky hieu sau: Cg - nong dp tap trang cua nguyen to A vao A^B^ tren bien gidi lien ket A | A_^B^; c - nong dp can bing cua nguyen to A; c - nong dp A A^B^ tren bien gidi A^B^ I B; Ay - mat dp phan ling tren be mat lien ket ldp A^B^ | B, bing so mdn nguyen to B hi bien mat mot don vi thdi gian tu mot don vi dipn tich la: / = 1/(2M^ Ac) Doi vdi cap vat lieu Al - Fe va pha hinh Fe^Alj til gian trang thai can bing, ta xac dinh dupe: Ac = 0,0035 gam.nguyen tir/cm^ The tich mdn cua sat Mp^ = 7,097 cmVmdn Sau tinh cac gia tri dd ta nhan dupc f= 20,13, dieu dd trung khdp tot vdi cac so lieu thuc nghiem cdng trinh khac da trich dan la f = 18,67 [1] Theo ket qua chieu day ldp mang trang gian y = f (T, t), ngudi ta tinh toan dupc so hang K^, nang lupng boat hda phan ung khuech tan Q va he so khuech tan thuc theo eac md hinh (4) va (9) bang phuong phap binh phuong nhd nhat tren may tinh dien tir, ket qua cho bang Cac thdng so nhiet ddng cua ldp khuech tan K^ va Q theo tri so gan vdi so lieu nhan dupe cdng trinh [2] Doi vdi cap vat lieu sat armko (Fe) - nhdm A6 nang lupng boat hda hinh va phat trien Idn len cua ldp mang Q.^.^, Tnc ~ QT>Tnc'^°'^8 P^^ thuoc vao kct cau cua ldp hpp kim ban phu Khi ndng chay ldp hpp kim ban phu cd su tang dot bien cua toe gia tang ldp khuech tan la su thay doi cd budc nhay cua tinh di dpng cua cac nguyen tu nhdm, dieu dd chiing td bdi sd hang trade so mu phuong trinh (4) Sir dung cac gia tri tinh toan nhan dupc K va Q ngudi ta da tinh dupc gidi ban nhiet dp - thdi gian (xem hinh 2) xuat hien ldp lien kim loai cd chieu day tdi ban (y_ < pm) va danh gia dupc anh hudng cua sir phan bo cua cac nguyen to hpp kim hda cac ldp cau vat lieu bimetal < thep - nhdm TAP CHicaKHl VIET NAM V So - Thang nam 2011 NGHIEN ciiu-TRAODOI Bang 1: Cae thong s6 nhiet dpng phat trien cua lop khuech tan bimetal sit - nhom [1] T,oC K, cm^/s D, cm^/s Kg, cm^/s Q, kJ/mon Sat armko - nhdm A6 560 660 6,40,10" 3,35.10-1° 1,30.10-5 6,75.10-5 3,5.10^ 107,4 s i t armko - ACM 560 660 3,20.10-12 1,60.10-5 6,45.10-11 3,10.10-« 3,4.10" 398,8 s i t armko A^l 560 660 9,1.10-" 4,60.10-'° 1,85.10-5 9,20.10-5 3,3.10^ 104,5 Sit armko Al 99,99% 560 660 2,30.10-" 7,62.10-1° 4,65.10-1° 1,55.10-« 1,22.10' 225,7 Fe - Al 99,99% 660 740 1,50.10^ 2,60.10^ 3,0.10-5 5,25.10-5 3,3.10-2 54,7 Sat armko - nhdm A6 660 740 1,30.10-' 4,40.10-' 2,65.10-« 8,80.10^ 0,56 118,3 Sat armko - ACM 660 740 9,20.10-« 6,65.10-' 1,85.10^ 1,35.10-5 6,3.10^ 193,5 Bimetal Thanh phan hda hpc eac kim loai cau bimetal cd anh hudng manh den eac thdng so phat trien Idn len cua ldp mang trung gian Khi hpp kim hda nhdm bing cac nguyen to nhu Si, Mg va cac nguyen to Idiac (hpp kim ACM) nang lupng hoat hda phan img khuech tan tang dot bien Hieu qua dd quan sat dupc hpp kim hda thep bdi V, Ti, Si va Ni Vi du nhu: Idii hpp kim hda thep bdi V thi K^, = 1,2.10'° va Q = 367 kJ/mdn Rd rang, cac cac nguyen to lam can trd su hinh cac mam pha trung gian va sir khuech tan cua Al khdng dang ke Anh hudng ngupc lai qua trinh tren la hpp kim hda thep bang cac nguyen to C va Mn Hpp kim hda nhdm bing Si va sir dung thep cd ham lupng C, Mn thap cho phep nang nhiet dp hinh pha lien kim len 40 -^ 60 °C cao hon nhiet dp ket tinh lai cua thep va che tao mac thep hpp kim hda bdi nhdm dam bao dp vuot sau tdt den eac nhiet dp Idiac thi mang cac lien kim loai hinh hau nhu tren toan bp be mat lien ket ldp bimetal Ciing vdi su gia tang nhiet dp nung va thdi gian giir nhiet chieu day ldp mang lien kim cang tang Khi nung bimetal hpp kim nhdm AMr6 - thep Ididng gi 12X18H10T den 650 °C tren be mat hen ket ldp (Fe - AMr6) da xay phan ring hda hoc vdi su hinh cac pha cau tnic lien kim loai Chieu day tong cua viing lien kim vat lieu bimetal d cac nhiet dp nung khac tang dan theo thdi gian Wiuech tan theo quy luat parabdn Cac thdng so khuech tan phu thupc vao nhiet dp theo ham so mii Ket qua thuc nghiem nung mau bimetal va khao sat to chiic te vi bien gidi ldp sau dd cho thay: d moi nhiet dp nung cd mot chu ky khdng quan sat thay sir hinh cac lien kim loai, ma chiing xuat hien d nhiet dp 540°C chi sau vai gid nung mau bimetal dat ding nhiet Quan he nhiet dp cua chu ky dau dupc tinh toan bang phuong phap toan thong ke thuc nghiem: Tac gia cdng trinh nghien ciiu [2] da dua ket qua chieu day ldp lien kim hinh bimetal hpp kim nhdm AMr6 - thep khdng gi 12X18H10T cd ldp mang trung gian bang nhdm, nhan dupc bing phuong (11) t^ = 6,0.ia-'.exp (192,3/RT) phap can dinh Mau thi nghiem dupc cat tir phdi can Bieu thiic (11) cho phep xac dinh toe dp hinh ngudi va li mdi tradng chan khdng d khoang nhiet cae doan cua pha lien kim loai dau tien: dp 300 - 650 °C tiidi gian - gid Nhiet dp (12) N> = 9,6.10".exp (1 - 192,3/RT) u dupc chpn phu thudc vao dieu kien ban, phuong an niiiet luyen va che dp can (dap) Tuong tac cua cac kim Bang phuong phap vat ly nghien cim to chiic kim loai va su hinh ldp mang lien kim loai bit dau sau loai (ronghen quang pho, hien vi dien tir, ronghen cau mot khoang thdi gian tdi ban d nhiet dp nung da chpn tnic) va nghien ciiu to chiic te vi da khao sat cau tnic, Sau khoang thdi gian dd, nung vat lieu bimetal phan vimg bien gidi lien ket ldp bimetal thep S6 7-Thang7 nam2011 NGHIEN cuu-TRAODOI 12X18H10T (Fe-armko)-Afl 1-hpp kim AMr6 va xac dinh ring: cac giai doan dau tuong tac giua Al vdi Fe(thep) d trang thai pha rin cd quan sat thay hien tupng khuech tan trpi hon cua sit vao nhdm va tao mot ldp mang mdng la hon hpp FeAlj + Fe^Alj Nung ndng mau bimetal thep - nhdm den nhiet dp viing nhiet dp ket tinh lai cua thep dan tdi cd su thay doi rd ret cau tnic cua bien gidi lien ket ldp cac dieu kien thi nghiem dd vimg lien ket ldp bimetal xay qua trinh cudng hda khuech tan nhdm vao thep cimg vdi su hinh ldp mang lien kim loai Chieu day cua nd va gia tri nhiet dp - thdi gian tdi ban tai thdi diem xuat hien lien kim loai phu thudc vao phan hda hpc cac kim loai phan va dieu kien nung Khi tang nhiet dp nung va chuyen nhdm sang trang thai pha Idng tren bien gidi lien ket ldp bimetal cd phat hien thay mot so pha ma khoi lupng chinh cua chiing tir phia sat la eac lien kim Fe^Al^, cdn ttr phia nhdm la FeAl^ Khi thep 12X18H10T tuong tac vdi nhdm xuat hien ldp mang mdng lien kim cd phan phuc tap hon, dd cd su tham gia cua Ni va Cr Ngay tren eac lien kim dd, ngudi ta da xac dinh dupc 2,2 % Ni, 6,6 % Cr va 22,4 % Fe Doi vdi hang loat cac td hpp bimetal ngudi ta da xac dinh nhiet dp tdi ban, ma d nhiet dp cao hon can tnic vat lieu tai bien gidi ldp bimetal moi lien ket kim loai xay qua trinh thay doi manh ve mat chat lupng va dieu dd lam giam dp ben bam dinh giiia chiing Co tinh moi ban phu thudc dang ke vao miic hinh pha lien kim loai va chi giii d miic dat yeu cau chi cac giai doan dau tien cua qua trinh, xay sir phat trien theo chieu rdng cua chiing Ngay tai thdi diem hinh ldp mang lien tuc cua cac lien kim loai dd thi co tinh da bi xau di nhieu Nhiet dp tdi ban cho phep cac chi tiet bimetal thep - nhdm lam viec la khoang 500 - 520°C Bimetal thep 12X18H10T - AJ\l - hpp kim AMr6 cd mot vai dp ben, nd md rpng sau cac chu ky nung va hien tupng kem theo la cac budc hinh cac pha lien kim loai Quy luat ve phat trien Idn len cua ldp mang mdng lien kim loai vat lieu bimetal cho phep xac dinh dupc toe dp phan ling khuech tan d cac nhiet dp khac cua qua trinh va tinh toan xac dinh che dp ban dam bao tinh chat ben cho trade cua moi ban Cac nghien ciiu anh hudng ciia nito, dxy, nhdm, silic va cac tap chat Idiac nen thep cua bimetal nhdm - thep den nhiet dp bat dau phan ling khuech tan va hinh tren bien gidi lien ket pha lien kim loai da xac dinh dupc ring: su gia tang pham vi nhat djnh nong dp khdng lien quan tdi nito va dxy cao hon nhiet dp bat diu hinh lien kim loai Da cd de xuat su dung thep sdi vdi nhdm lam nguyen lieu dau vao cho phep che tao va tien hanh u ket tinh lai vat lieu bimetal Fe - Al d nhiet 610 ^ 630 °C ma khdng xuat hien pha lien kim loai Phan img Idiuech tan he Fe - Al cdn dupc quan sat thay d nhiet dp tren 400 °C Phan Idn khoi lupng ldp khuech tan la cae tinh the pha Fe^Alj, dinh hudng phan bo theo be mat song song vdi mat tiep xue ldp [1] KET LUAN 1) Cac ket cau thep - nhdm tong hpp dupc dp ben nhiet, cimg, dp ben mdn cao cua thep vdi mat nhd va dp dan nhiet cao ciia cae hpp kim nhdm cd the nhan dupc ban nhdm vdi thep d trang thai ran hoac Idng mot each tdt nhat, phu thudc vao nhieu yeu to cdng nghe va rat khd khan, vi sat (Fe), nhdm (Al) va hpp kim nhdm da dupc su dung bien ky thuat, nhung cac quy luat anh hudng cua tuong tac giiia chiing tdi chat lupng ket cau ban cho den cdn chua dupe nghien cim chuyen sau mot each ky ludng, d Viet Nam hien la van de kha mdi me; 2) Su phat trien Idn len cua ldp mang cac pha lien kim tren bien gidi thep - hpp kim nhdm ban xet ve mat nang lupng la Ichdng ed Ipi the Han nhdm vdi thep cd the thuc hien d trang thai ran bang phuong phap can ngudi, ban nd hoac ban Idng tir hai kim loai han cd nhiet ndng chay khac xa chi ed mot kim loai bi ndng chay d nhiet dp thap hon Xet ve thdi gian cdng nghe ciing nhu trang thiet bi cdng nghe can cd de tao moi ban giiia thep va nhdm dieu kien Viet Nam hien thi cdng nghe ban no la tuong ddi phu hpp cho viec che tao vat lieu ldp thep - nhdm - hpp kim nhdm sir dung lam chi tiet trung gian ddng mdi va sua chiia tau bien.»> Tai lieu tham khao: [1] PaSoB B P (1983): "Ceapna OJIIOMUHUJI U ezo cnnaeoe c dpyzuMu MemamoMU ", Hsflax "HayKOBaflyMKa",KneB, 263 c.; [2] JIapHKOB JI H., PaSoB B P, OajiBHeHKO B M(1975): "JJu4)^)y3UOHHbie npotfeccbi e meepdou jmse npu ceapne" M., MaiuHHOCTpoeHHe, 192 c; [3] Ha Minh Hung, Luang Van Tien (2008); "Vat lieu to hap thep - nhom - hap kim nhom dimg cdng nghiep dong tau thuy", Bao cao khoa hoc tai Hoi thao khoa hoc toan quoc "Cong nghe vat lieu va be mat" (Thai Nguyen 2008), Tap chi Khoa hpc va Cong nghe so (48), Tap 2, trang 57-67 S o - T h a n g nam2011 ... lien kim loai ciiu ly thuyet va thuc nghiem ve eo che va ddng hpc sat - nhdm va nhdm (hoac hpp kim nhdm) Tinh chat qua trinh hinh lien ket kim loai giiia hpp kim cua vat lieu Idp mang mdng lien kim. .. hinh dang, dac Nga, Vien Luyen kim den Uran, Vien hpp kim Mau tinh phan bd va cac tinh chat cua Idp mang mdng lien va Vien Luyen kim mang ten A A Baikov (Lien bang kim loai Nga); Trung tam NASA... cuu-TRAODOI Trd ngai Idn nhat viec tao lien ket kim loai giiia nhdm va hpp kim nhdm vdi thep chinh la tuong tac hda hpc giiia cac kim loai dd, dan tdi hinh cac lien kim loai tren dudng bien gidi lien ket