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Chng 6. Hp kim mu
Kim loi en Fe & HK Fe-C
Kim loi mu KL cn li & HK ca chng
t hn KL en6.1. Hp kim nhm:
u im: ( so vi Fe v HK Fe-C)
- nh ( hn 3 ln)
- tng i bn ( HK siu bn thpkt cu)
- tnh chng n mn cao
- tr lng ln
c s dng rng ri
6.1.1. Nhm nguyn cht:
1. c tnh:
kiu mng lptm
khi lng ring nh( 2,7g/cm3)
tnh chng n mn tt ( Al2O3trn b mt
mng v xt cht)
dn in, nhit ttT0 chy thp
bn thp, mm ( b= 60MPa; 25HB)
2. Cc mc nhm nguyn cht :
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Tp cht : Fe, Si ( Fe Fe3Al gin c hi)
Chia ra 3 nhm:
- Sch c bit: A999 ( 99,999%)
- Sch cao: A995- Sch k thut: A85, A8; A7..A0 dng c gia
nh
3. Phn loi: theo gin pha Al- NTHKchia ra
2 nhm
a. HK Al bin dng:
thnh phn: bn tri Cd bin dng do
bn tri F ( ch c pha )khng ho bn bng
NL
bn phi F ( + pha th 2) ho bn bng NL
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b. HK Al c:
%Me cao t chc cha ch yu l cng tinh
c. Ngoi ra gn y cn dng HK bt Al+ Al2O3
thiu kt6.1.2. Hp kim nhm bin dng : (ho bn
bng NL)
1. HK Al- 4% Cu:
L c s ca hu ht HK Al bin dng
T0= 548 5,65%Cu tan vo AL
T0 thng 0,5%Cu
Khi ngui Cu tit ra di dng CuAl2 (t dung dchrn)
HK Al-4%Cu T0 thng : ( Al(0,5% Cu)) + CuAl2 (
7%)
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b= 200MPa
Khi ti (>5200C) dung dch rn qu bo ho Cu
b= 250MPa
( tng t)Sau ti 5-7 ngy b tng mnh 400MPa ho gi
t nhin
( sau ti sa nn c)
C ch ho gi: ( Gunier v Preston)
Dung dch rn qbh sau ti khng n nh v
trng thi cn bngtit ra Cu v tp trung li
CuAl23 giai on:
+ giai on 1: Cu >4% mt s vng ( vng GP)
kch thc b, hnh a( r=5n.m)x lch mng
cao cng, bn cao
+ giai on 2: Cu trong vng GP tip tc tp trung
t n 1Cu-2Al GP ln ln ( r=10n.m)( c
bn cao nht) sau thnh pha
( bn gimi)
T0 thng qu trnh dng giai on ny ( 5-7
ngy) v duy tr mi
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+ giai on 3: T0>50-1000, ( CuAl2): trng thi
cn bng, kch thc ln mm
Pha CuAl2 l pha ho bn
NL ho bn l Ti + ho gi :
ho gi t nhin 5-7 ngy
ho gi nhn to T= 100-2000C, hng
chc gi
2. Hp kim Dura:s dng rng ri nht
a. Thnh phn ho hc:
Al- 4% Cu- 1%Mg
Cu, Mg nng cao hiu qu ho bn bng
NL+Ho gi
Ngoi ra c Fe,Si v Mn(tng tnh chng nmn)
b. T chc t vi:
c cc pha CuAl2; Mg2Al3; CuMgAl2; CuMg5Al5
ho tan c hn vao ddrn khi ti tit ra khi ho
giho bn
c. Cc mc HK nhm :
AlCu 4,5Mg0,5MnSi
AlCu4,5Mg1,5Mn0,5
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bn cao ( 420-470MPa), khi lng ring nh
vt liu my bay
6.1.3. Hp kim nhm c: HK trn c s Al-Si
Silumin
1. Silumin n gin :
Ch gm Al-Si; 10-13% Si
T chc : cng tinh Al-Si tnh c tt
Bin tnh nhn c Cng tinh nh mn
( 2/3NaF+ 1/3NaCl) vi t l 1% HK lng
2. Silumin phc tp:
Tnh c tt
C thm Cu, Mg c tc dng NL ho bn
( ti+ho gi)Thnh phn: ( thay i ): 4-30% Si ;
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1. c tnh:
kiu mng lptm
khi lng ring ln ( 8,94 g/cm3)
t
dn in v nhit cao
T0 chy = 1083
d cn, ko
b= 160 MPa ; sau BD : b= 450 MPa2. Cc mc ng nguyn cht :
Cu99,99; Cu99,97; Cu99,95; Cu99,90
3. Phn loi HK Cu :
C tnh cao; tnh CN tt, t ma st, dn in,
nhit tt, doTheo tnh CN chia ra: HK bin dng v c
Theo thnh phn ho hc : Latng v Brng
( thng gp)
6.2.2. Latng: Hp kim Cu- Zn ( ch yu)
1. Latng n gin:
ch gm Cu-Zn
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thc
t ch
dng 45 ( ch c 1 pha
)
c. Latng 1 pha: (< 39% Zn)
do, bn tng i cao, r ( hn ng nguyn
cht )
Mc : LCuZn30; LCuZn 32 dp su ( v n)
d.Latng 2 pha: 39
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a. Brng Sn:
NTHK: ch yu Sn
%Sn
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6.4.1. Khi nim chung: ch to cc chi tit
khc vi phng php truyn thng
I. Ph ng php ch to:
To bt KL v HK c thnh phn ng vi yucu trn u
To hnh: p , nn vi p lc cao: 100-1000MPa
( tu theo yu cu khi lng ring ca chi tit)
Thiu kt: cc ht bt lin kt bn vng vi
nhau v tng c l tnh cho sn phm n gi
tr mong mun
II. c im ca ph ng php:
V kinh t: nguyn liu c s dng trit ,
khng hoc t phi gia cng ( sa hoc ct), s
kinh t khi sn lng cao
V cht lng: d m bo ng nht v thnh
phn, t chc, kch thc trn u
V t chc t vi: cu trc khng xt cht, lun
c l hng ( 2-50%), c tnh khng cao6.4.2. Vt liu ct v mi:ng dng
ln
nht ca VL bt hin nay
I. Hp kim cng:
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Tnh cng nng cao: 800-10000C
Tc ct n hng trm m/ph
cng : 70-75HRC
Thnh phn: 3 loi
+ Loi 1 ccbt: bt WC+ bt Co ( dnh kt)
ct gang,s...(phoi vn)
+ Loi 2 ccbt: bt WC+TiC + bt Cogia cng
tinh thp
+ Loi 3 ccbt: WC+ TiC+ TaC+ bt Cogia
cng th thi c,rn,cn
II. a ct:
L Vt liu siu cng: 8000-10.000HV
Cc dng:+ Bt kim cng vi 1-2% bt B, Be, Si p di p
lc ln
Tthiu kt=30000C
+ Bt kim cng ( hoc BN) tri trn b mt HK
cng p di p lc ln; Tthiu kt=18000C
+ Bt kim cng hoc BN trn vi bt KL( 20-
30%);
Tthiu kt=1200-16000C ; dao ct
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+ Dao bng BN u vit hn dao kim cng (tc
ct gang xm n 1800-2000m/pht)
III. Bt mi: ht cng , thng l:
+ ct ( SiO2); bt Al2O3; SiC; kim cng+ cc dng : giy, vi, khi, bt
t do
