Caky condition and magnesium are right Al

Structure of crystal of 0 alloy branch and in all the influence that brilliant organizes. Test result makes clear, as the addition of cooling rate, al-Si11.

The branch brilliant of 0 alloy and 2 ramose span are reduced significantly; When minor cooling rate, 2 times of the alloy after adding magnesian element ramose span increases apparently, and when cooling rate is more than 160K/min, do not have an influence. The experiment returns discovery, after adding magnesian element, cooling rate is right in all the influence of brilliant composition is reduced significantly. Raise cooling rate to make of alloy in all brilliant organizes attenuate. Inside test range, al-Si11.

Join in 0 alloy 0.

When 15% magnesium, in all brilliant organization becomes thicker; And when magnesian affiliation the quantity increases to 0.

3% when, its in all brilliant organization compares Al-Si11.

0 alloy are fine much, analysed appear the reason of this one result. Keyword aluminium alloy is directional and caky microstructure Effect Of The Cooling Conditions And Mg Content Onthe Microstructures Of Al-Si11.

0AlloyXu Cailu 　 (Dept.

Of Mechanical Engineering, tsinghua University, beijing)H.

M.

Tens 　 R.

Roesch 　 (Dept.

Of Mechanical Engineering, technical University Munich, germany) 　 [Abstract] 　 Effect Of Cooling Conditions And Mg On The Dendritic, eutectic Structures Of Al-Si11.

0 Alloy By Unidirectional Solidification Was Investigated.

160K/min) of ＜ of The Results Show That With Increase Of The Cooling Rate The First Dendritic Spacings And Second Dendritic Arm Spacings Are Evidently Decreased;Mg Addition Raises The Dendritic Arm Spacing Considerably At The Low Cooling Rate (, while It Has No Significant Influence On Dendritic Arm Spacings At High Cooling Rate.

Enhancement Of The Cooling Rate Fines The Eutectic Structure Of Al-Si11.

0 Alloy.

In All Experimented Cooling Conditions The Alloy With The Addition Of 0.

15% Mg Possesses The Coarsest Eutectic Structure, while The Alloy With The 0.

3% Mg Addition The Finest Structure In Eutectics.

After the composition when a kind of casting alloy decides preface of Microstructure1 of 　 of Unidirectional Solidification of 　 of Keywords 　 Aluninium, its cast an organization to basically decide condition of Yu Ning firm. Because directional and caky craft can control the floating rate V of the temperature gradient G of caky interface forward position and caky interface independently, make people controls caky condition well and truly. Pass mensurable metallographic analyzer, can decide the feature of caky organization, describe the relationship of caky organization and caky condition thereby. Medium caky organization can divide Al-Si alloy to be mixed for branch brilliant in all brilliant organization. To directional and caky the branch crystal structure of gotten α Al solid solution can be mixed 2 times by E of branch brilliant span ramose span Ds will show rate of degree of finish. According to Hunt [1] with Kurz [2] experiment, the temperature gradient G of branch brilliant span and caky speed V and caky interface forward position has following concern: E=k. G-1/2. 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of V-1/4 　 　 (1) among them, k is the constant that decides by test result. In 2 the relation respect of ramose span Ds and cooling rate had done a lot of works, and already obtained satisfactory result. According to Kattmis [3] report, both concern can indicate with next type: Ds=B0. (　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of M × Vf)-1/3 (2) among them, b0 is the constant that concerns with branch brilliant appearance, m is to decide the constant at material. Other test results show, according to alloy composition different its index uprights at - 1/2 and - between 1/3. Cooling condition is right the odd liquid state between branch brilliant - in all brilliant composition or over- in all the coupling of brilliant composition grows the organization has very big effect as much, this kind of their relation also can use mensurable metallographic analysis to get [4, 5] . In this job, the directional and caky device that uses Munich industry university and mensurable metallographic analyse equipment, studied cooling condition and microelement magnesium are right Al-Si11.

Brilliant of 0 alloy branch, in all the influence that brilliant organizes. Shape of cylinder of 2 experiments condition tries a club to be on the directional and caky device of institute of material of project of machinery of Munich industry university [6] caky get. Caky parameter namely the temperature gradient G of caky speed V and caky interface forward position by two thermocouple (diameter 0.

The bougie that 2mm) comprises is measured and direct input computer is handled. The raw material of the experiment is offerred by Alusuisse-Lonza company of Switzerland. If the composition of sample expresses 1 to show. The temperature gradient G of caky interface forward position controls the limits in 20(± 2)K/mm as far as possible inside, and caky speed V is in 2 ～ change inside 30mm/min. The watch uses Al-Si11 1 times.

The composition of 0 alloy (Composition Of Al-Si11 of Wt%)Table 1 　 .

SiMgFeMnCuZnAl-Si11 of 0 Alloy(wt%) alloy.

011.

0- ＜ 0.

002 ＜ 0.

001 ＜ 0.

001 ＜ 0.

001Al-Si11.

0Mg0.

1511.

00.

15 ＜ 0.

002 ＜ 0.

001 ＜ 0.

001 ＜ 0.

001Al-Si11.

0Mg0.

3011.

00.

29 ＜ 0.

002 ＜ 0.

001 ＜ 0.

001 ＜ 0.

Sample of 001 　 metallographic stabilizes caky parameter area to be cut inside the country from what try a club take. E of branch brilliant span and Ds of 2 ramose span part to vertical,be mixed in the cross section of sample sectional on measure get [7] . Following in all the parameter of brilliant area go up by a semi-automatic mensurable metallographic analyzer get: In all the area of brilliant area (bulk) mark; In all the area of photograph of the Si- in crystal (bulk) mark; In all the geometrical dimension of particle of the Si- in brilliant area (size of average length area, appearance coefficient [10] wait for) ; In all of brilliant Si refine degree (on unit area in all the amount) of brilliant Si; In all span of brilliant Si average freedom. 3 tests result and discuss 3.

The influence of 1 caky parameter to branch crystal structure is directional and caky V of medium temperature gradient G and caky speed is right if the influence of one Ci Zhijing span pursues 1a place is shown; Graph 1b showed the caky parameter effect to Ds of 2 ramose span. From the graph 1 visible, e of branch brilliant span and Ds of 2 ramose span all follow V of × of cooling rate G increase and reduce. Here also can see the effect of magnesian element: When inferior cooling rate (make an appointment with 40K/min) , al-Si11.

0Mg0.

3 with Al-Si11.

0Mg0.

2 times of 15 alloy ramose span is more than the Al-Si11 that did not contain magnesium apparently.

The Ds of 0, it is when higher cooling rate, criterion 3 kinds of alloy have similar Ds to be worth (2) seeing a table. Graph 1 cooling rate is right branch brilliant, the influence Fig of 2 Ci Zhijing span.

Alloy of Dendritic Arm Spacibng Atvarious Solidifing Conditions of 　 of M)Table 2 of μ of Ds(of 2 when 1 　 Influence Of Cooling Rate On Dendritic Spacingand Dendritic Arm Spacings expresses 2 different and caky conditions to fall ramose span 2 ramose span, μ MVEF=2mm/minVEF=8mm/minVEF=30mm/minAl-Si11.

028.

4720.

3812.

30Al-Si11.

0Mg0.

1535.

2222.

3413.

71Al-Si11.

0Mg0.

3041.

2921.

5012.

Because join the caky interval that alloy increased after magnesium,the influence of 27 　 magnesian element to Ds of 2 ramose span basically is (be in directional and caky in it is branch brilliant namely caky interface and in all brilliant is caky distance) of the interface. According to document [8] , special when inferior cooling rate, magnesium has apparent effect to the caky interval of aluminum-silicon alloy (watch 3) , when affecting same cooling rate thereby caky (thick change) time, cause the addition of ramose span Ds 2 times. Document [9, 10] point out, si will be reduced to expand mediumly in Al fluid after joining magnesium, cause 2 times then reduce ramosely (of δ of area of rich collect of solute of branch brilliant pointed ministry reduce [11] ) , this kind of influence and the influence above just contrary. See from experimental result, when inferior cooling rate, magnesian affiliation makes 2 times ramose span increased, the specification is main to the influence of caky interval. And when high cooling rate, magnesium appears negligible to Ds influence. Express 3 caky speed to be mixed to branch brilliant in all brilliant is caky the brilliant of branch of alloy of Influence Of Solidification Rate On Distance Betweendendritic And Eutectic Solidification Front of 　 of influence Table 3 of interfacial span and in all brilliant is caky interfacial span, mmVEF=2mm/minVEF=8mm/minAl-Si11.

00.

390.

74Al-Si11.

0Mg0.

300.

670.

Although the to E of branch brilliant span influence after 96 　 join magnesium is lesser, but the effect and ramose to 2 effect are similar. 3.

2 caky conditions and magnesium are right Al-Si alloy in all the influence of brilliant composition the addition as cooling rate, the bulk mark of photograph of brilliant of Al-Si alloy the Communist Party of China decreases significantly (graph 2a) , at the same time in all the Si content in brilliant photograph increases accordingly (graph 2b) . Graph 2 in all crystal bulk mark and Si are in in all the relation Fig of the bulk mark in crystal and cooling rate, quantity that contain magnesium.

2 　 Relationship Between Si Volume Fraction Ineutectic And Cooling Rate, maguesium Content 　 is here, the effect that adds magnesium is clear also and visible. Join magnesium 0.

Of 3% alloy in all the bulk mark of crystal cools in the experiment Al-Si11 is compared below the condition.

0 alloy are low 10.

0% the left and right sides, and two kinds of alloy rise and increase what the difference of brilliant composition follows cooling rate in all (graph 2b) . N duality of 17%) of 5 ％ ～ is in Al-Si(Si content in alloy, steen [12] and Tensi and Pek [13] test result makes clear, cooling rate is right Al-Si in all the influence of brilliant composition is great, below high cooling rate, al-17.

0Si alloy also can get do not containing Chu Jing Si all in all crystal organization. See Al-Si11 by graph 2b.

0 with Al-Si11.

0Mg0.

3 alloy the difference of brilliant composition rises along with cooling rate and increase in all, join a few magnesian element reduced the current that brilliant composition increases along with cooling rate and lifts in all. 3.

3 caky conditions and magnesian element are right Al-Si in all the influence that brilliant organizes is caky condition and magnesian content not only influence Al-Si11.

Among brilliant of 0 alloy branch in all crystal is measured and in all brilliant composition, and right in all brilliant is organized (Si is in in all the configuration in crystal) also have apparent effect. Of 3 kinds of alloy in all brilliant organization follows cooling rate rise and attenuate. Analyse as ration in all brilliant Si organization, by try in every extraction cross section is cut to will determine on the club about 2000 in all brilliant Si particle and get " in all brilliant Si particle is average area A " and " in all brilliant Si refines degree of ε " will measure. In all the size of brilliant Si particle and distributing and in all if the relation that brilliant Si refines degree of ε and cooling rate pursues 3, 4 are shown. Graph 3 in show clearly, when cooling rate is inferior, in all the average and free span between the area of brilliant Si and them decreases quickly as the addition of cooling rate, when cooling rate is more than 200K/min, cooling condition is right in all the influence that brilliant Si particle does not have essence. Suit to it, express unit area to rise and increase what brilliant Si refines degree of ε to follow cooling rate what brilliant Si particle counts in all in all (4) seeing a picture. Graph 3 cooling rate and magnesian content are right in all the size of brilliant Si particle, influence Fig that distributing.

　 of 3 　 Influence Of Cooling Rate And Mg Content On Size And Distribution Of Eutectic Si Particle pursues 3 in magnesian affiliation is right in all the influence of brilliant Si is clearly. Below all experiment condition, in Al-Si11.

0, al-Si11.

0Mg0.

15 with Al-Si11.

0Mg0.

In 3 kinds of 3 alloy in order to join 0.

Of 3%Mg alloy in all brilliant Si organization is the finest, and join 0.

The organization of 15%Mg alloy is the thickest, did not join magnesian Al-Si11.

The dimension of 0 uprights at before both among. Graph 4 in all brilliant Si particle refines degree of relation Fig with cooling rate and magnesian content.

4 　 Relationship Between Eutectic Si Pareide Finenessand Cooling Rate, magnesium of Maguesium Contect 　 is right alloy in all the influence of brilliant Si photograph is OK get explanatory in following analysis. When Al-Si11.

Join in 0 alloy 0.

When 15%Mg, the place before be like is narrated, added alloy branch any crystalline substance caky interface and in all brilliant is caky interfacial distance, increased namely in all brilliant is caky of the Si in the process thick spend time, because this got thicker in all the Al-Si of brilliant Si particle in all brilliant organization. When magnesian affiliation the quantity increases to 0.

3% when, because had more magnesian atom, at that time magnesium reduces Si to diffuse mediumly in Al fluid a dominant action, obtain thereby pettier in all brilliant Si particle. Graph 5 gave out cooling rate and magnesium are right in all the influence of factor of brilliant Si appearance. Can see from inside the graph, below all cooling conditions of the experiment, with in all brilliant Si average size and in all brilliant Si refines the result that spends ε to answer relatively, al-Si11.

0Mg0.

The appearance factor of 3 alloy is the biggest. Graph 5 cooling conditions and magnesium are right in all the influence Fig of factor of appearance of brilliant Si particle.

What 　 of 5 　 Influence Of Cooling Condition And Magnesiumon Form Factor Of Eutectic Si Particles follows cooling rate is elevatory, in all the appearance factor incline to of brilliant Si at 1.

0, namely the appearance with sectional Si is close to Yu Yuan. This kind of trend also can see in organization of brilliant Si metallographic in all. 4 conclusion 　 (1) caky condition affects Al-Si11 not only.

The branch crystal structure of 0 alloy, and to branch brilliant between in all brilliant organization also has apparent effect. After adding magnesian element, 2 times of alloy ramose span is in low cooling rate (increased when 40K/min) , and when high cooling rate, magnesium is right Al-Si11.

2 times of 0 alloy ramose span Ds does not have apparent effect. (The affiliation of 2) magnesium is right Al-Si alloy in all brilliant composition has apparent effect. After joining magnesium, cooling rate is right in all the influence of brilliant composition is reduced significantly. (The 3) addition as cooling rate, of alloy in all brilliant organizes attenuate. Should add magnesian capacity for 0.

15% when, of alloy in all brilliant is organized relatively Al-Si11.

0 thick, should add magnesian capacity for 0.

3% when, criterion of alloy in all brilliant organization compares Al-Si11.

0 fine much. CNC Milling CNC Machining