Fe3Al/18

Normal > summary: Use scanning report lens (SEM) and electronic bougie (EPMA) analysed the structural feature near interface of Fe3Al/18-8 diffusion welding, studied the interface diffuses reaction layer ply and heat the relation between temperature and heat preservation time, derivation outside face diffuses of reaction layer grow the rule. The result makes clear, feAl, Fe3Al, Ni3Al and α are formed near interface of Fe3Al/18-8 diffusion welding - Fe (Al) solid solution, these photograph structures are helpful for promoting interfacial element diffuse reach diffuse the happening of reaction. The interface diffuses the conceal time T0 with react the formation of the layer has certain, the growth of reaction layer follows parabola pattern, its ply X and heat the relation of temperature T and T of heat preservation time is X2=4.

5 × 10-4exp(-55.

7/RT)(t-t0) . Normal > keyword: Normal >0 introductive Normal >Fe3Al is to have the compound between the DO3 metal that exceeds latticedot matrix structure in order, hardness it is caustic of tall, wear-resisting, better to fight vulcanization and corrosion resistance [1-3] , stainless steel is current anti-corrosive the uses extensively steel below the circumstance. If can the complex component part that preparation gives Fe3Al and stainless steel, sufficient play two kinds of material are in function and economically advantage are complementary, in aerospace, petro-chemical, electric power the domain such as construction has wide applied perspective [4] . How to realize the join of Fe3Al and stainless steel, have important sense. Fe3Al because brittleness is bigger, it is easy to use fusion welding method generation solders crackle, and vacuum diffusion welding belongs to solid state to diffuse join, its solder the process is undertake in vacuum atmosphere, accordingly, use craft of vacuum diffusion welding to solder Fe3Al and stainless steel are heterogeneous material, can avoid effectively to solder the generation of crackle. Document [the craft of vacuum diffusion welding to Fe3Al and 18-8 stainless steel undertook 5] consider, put forward appropriate craft parameter, but the growth of the structural feature near interface of concerned Fe3Al/18-8 diffusion welding and interfacial reaction layer behavior has not appear in the newspaper. Normal > literary grace uses scanning report lens (SEM) the structural feature near interface of observation Fe3Al/18-8 diffusion welding, use electronic probe (EPMA) diffuse to Fe3Al/18-8 interface the composition of reaction layer undertakes an analysis, studied the interface diffuses reaction layer ply and heat the relation between temperature and heat preservation time, reach the interface diffuses of reaction layer grow the rule. Of Fe3Al of this pair of research and other data solder, advance the compound between Fe3Al metal to provide experiment foundation and academic basis in the application in engineering construction. Normal >normal >1 test data reachs methodological Normal > test data is the compound between Fe3Al metal and 18-8 austenite stainless steel. Among them Fe3Al is the board that after passing fusion of vacuum induction furnace, makes, chemical composition and visibility of hot physics sex are expressed 1. Use line cut method to cut Fe3Al and 18-8 stainless steel 100 × respectively 20 × 20mm3 and 20 × of 100 × of 8mm3 wait for solder to try board. Normal > solder board ferruginous, impurity of the surface and oxidation film purify. Next will two try board alternate to close together, put into the vacuum room of equipment of Workhorse Ⅱ diffusion welding, fluctuation surface places one cloudlet parent each, in order to prevent the felt of sample and pressure head. Solder resistor radiate is used to heat in the process, parameter of diffusion welding craft is: Heat temperature 1000~1080 ℃ , 15~80min of heat preservation time, solder pressure 15MPa, vacuum is spent 4.

0 × 10 - 4 Pa. Normal > solder take contact of Fe3Al/18-8 diffusion welding and preparation becomes metallographic sample, undertake cankerous with aqua regia solution. Use lens of JXA-840 scanning report to analyse the structural feature near interface of Fe3Al/18-8 diffusion welding; Use JXA-8800R electron probe (EPMA) analytic Fe3Al/18-8 interface diffuses the composition of reaction layer; According to Bujiakefu (B.

E.

Eyrakob) the element that offer diffuses the interface of Fe3Al/18-8 of parabola rule research between distance and time diffuses the growth of reaction layer the rule. Normal Align=center> watch and Normal Align=center> chemical composition (quality mark, %) Fe Normal Align=center>Al Normal Align=center>Cr Normal Align=center>Nb Normal Align=center>Zr Normal Align=center>B Normal Align=center>Ce Normal Align=center>80.

2 Normal Align=center>15.

7 Normal Align=center>1.

5 Normal Align=center>2.

1 Normal Align=center>0.

3 Normal Align=center>0.

1 Normal Align=center>0.

2 Normal Align=center> heats up Normal Align=center> is orderly and critical temperature Normal LINE-HEIGHT of ℃ of Exactly" Align=center>T / : 12pt; TEXT-ALIGN: Center; Mso-line-height-rule: Model of Exactly" Align=center> Yang measures Normal Align=center>G /GPa Normal LINE-HEIGHT of Exactly" Align=center> melting point: 12pt; TEXT-ALIGN: Center; Mso-line-height-rule: Normal Align=center>T / : 12pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center> heats up Normal Align=center> α / 10-6 · K-1 Normal LINE-HEIGHT of Exactly" Align=center> density: 12pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center> ρ / Normal Align=center> σ δ (%) Normal LINE-HEIGHT of Exactly" Align=center> hardness: 12pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center>HRC Normal Align=center>DO3 Normal Align=center>540 Normal Align=center>140 Normal Align=center>1540 Normal Align=center>11.

5 Normal Align=center>6.

7 Normal Align=center>455 Normal Align=center>3 Normal LINE-HEIGHT of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 29 of Exactly" Align=center> ≥ : 15pt; Mso-line-height-rule: Exactly">normal > foundation project: National science foundation funds a project (50375088) , shandong saves science foundation to fund a project (Y2003F05) Normal >2 result and discussion Normal >normal >2.

1 interface diffuses the constituent structure Normal >Fe3Al and 18-8 steel diffusion welding, in craft parameter (T, t, p) fall with the integrated action of chroma gradient, the element in mother capable person diffuses to osculatory interface ceaselessly. When reaching certain consistency, happen between the element diffuse reaction, form around osculatory interface have what organize a structure unlike mother capable person to diffuse reaction layer. Graph 1 show an interface of the Fe3Al/18-8 below different technology parameter to diffuse the feature of reaction layer. (Interface of 1 Fe3Al/18-8 of graph of 30min of × of ℃ of 60min(b) 1040 of × of A) 1020 ℃ diffuses the diagnostic Normal >Fe3Al/18-8 diffusion welding as a result of the element diffuse, feature of structure of the organization inside reaction layer is distributing on matrix photograph have a lot of precipitate. Transfer through the interface from Fe3Al 18-8 steel, the precipitate configuration inside each area differs somewhat. And, as heat of temperature lift and the extension of heat preservation time, fe3Al/18-8 interface diffuses reaction layer ply increases gradually, the organization inside reaction layer gradually thick change. Test result makes clear, fe3Al/18-8 vacuum diffusion welding heats ℃ of temperature T =1040, when T = 45~60min of heat preservation time, can obtain those who have certain ply to diffuse reaction layer. Normal > diffuses for the analysis the structure that forms inside reaction layer, use EPMA to undertake metrical to the composition near Fe3Al/18-8 interface, measure the position and result to see a picture 2. (A) measures the place (interface of 2 Fe3Al/18-8 of B) composition distributinging graph diffuses reaction layer EPMA measures the position and result Normal > diffuses in Fe3Al/18-8 interface inside the small zonule of a side of reaction layer close Fe3Al, because Al diffuses the effect that Cr, Ni suffers in the process, content increases suddenly, in the section rich volume with close Fe3Al minor a side, content forms the compound between FeAl metal higher. From diffuse reaction layer transfers 18-8 steel, content of Al, Fe is reduced gradually, content of Ni, Cr increases gradually, basically form Ni3Al and α - Fe (Al) solid solution. Among them, ni3Al is the result that the Al in the Ni in 18-8 steel and Fe3Al is soldering to diffuse in the process and react each other. In the meantime, solder the Al in the Fe3Al in the process diffuses to 18-8 steel a side ceaselessly, in content of a side of close 18-8 steel inferior, α is formed after refrigeration - Fe (Al) solid solution. Normal >2.

The growth of layer of 2 interfaces reaction regular Normal > vacuum diffusion welding diffuses is process of trends of balance of a blame [6] . Different heat below temperature, fe3Al/18-8 interface diffuses of reaction layer Al, Fe, Cr, Ni diffuse the relation between distance and square root of heat preservation time is shown 3 times like the graph. Normal > heats certainly below temperature condition, fe3Al/18-8 interface diffuses of reaction layer Al, Fe, Cr, Ni diffuse the square root of distance and heat preservation time shows linear concern approximately, namely both between rule of contented and undermentioned parabola [7] : (1)normal > type: X - diffuse distance, μ M; Ci - elemental chroma, % ; Δ C - the chroma of two side needs the interface, % ; D0 - diffuse factor, μ M2/s; Q - diffuse activation can, j/mol; R - gas constant, 8.

314J/(molK) ; T - heat temperature, k; T - heat preservation time, s; T0 - preclinical time, s. Normal > basis is formulary (1) , beg solution to give element of Al, Fe, Cr, Ni to diffuse in Fe3Al/18-8 interface reaction layer diffuses mediumly activation can Q and diffuse factor D0, computation sees a table as a result 2. Normal > by the watch 2 visible, the element diffuses in Fe3Al/18-8 interface of reaction layer diffuse activation can be compared small in Fe3Al and 18-8 steel matrix. And computation makes clear as a result, identical diffusion welding heats below the condition, al, Fe, Cr, Ni is in diffuse the diffusion coefficient in reacting medium diffusion coefficient all is more than the layer to reach 18-8 steel in Fe3Al. Because photograph of relatively as even as constituent composition matrix of mother capable person is compared,this is, the constituent structure of layer of reaction of interface of Fe3Al/18-8 diffusion welding more those who be helpful for stimulative element diffuse reach diffuse the happening of reaction. Normal > same technology diffuses of the element in reaction layer diffuse the distance is different, when computation with the element the biggest diffuse the distance states the interface diffuses the ply of reaction layer. the list 2 medium data generation join formula (1) , the Fe3Al/18-8 interface that computation gets diffuses reaction layer ply (the computational formula of X) is: (Result of 2) general computation and electronic bougie (EPMA) actual measurement result undertakes comparative making clear (see a picture 4) , fe3Al/18-8 interface diffuses the computational value of reaction layer ply is more than EPMA actual measurement to be worth a bit, because be when computation,this is with the element the biggest diffuse distance delegate diffuses the cause of reaction layer ply. But when time of heat preservation of control diffusion welding is less than 60min, diffuse the computational value of reaction layer ply and value of EPMA actual measurement differ lesser. Square root of heat preservation time / S1/2 (a) Al (b) Fe (c) Cr (d) Ni Normal Align=center> graph diffuses of reaction layer element diffuse distance Normal LINE-HEIGHT between Exactly" Align=center> and heat preservation time: 15pt; TEXT-ALIGN: Center; Mso-line-height-rule: Interface of 2 Fe3Al/18-8 of Exactly" Align=center> watch diffuses in reaction layer of each element diffuse factor (D0) and diffuse activation can (Q) Normal LINE-HEIGHT of Exactly" Align=center> parameter: 15pt; TEXT-ALIGN: Center; Mso-line-height-rule: Normal Align=center>Fe3Al: 15pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center>Fe3Al/18-8 interface diffuses reaction layer Normal LINE-HEIGHT of ① of Exactly" Align=center>18-8 steel: 15pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center>Al Normal Align=center>Fe Normal Align=center>Cr Normal Align=center>Al Normal Align=center>Fe Normal Align=center>Cr Normal Align=center>Ni Normal Align=center>Fe Cr Normal Align=center>Ni Normal LINE-HEIGHT of · of M2 of μ of Exactly" Align=center>D0 /106: 15pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center>1.

7 Normal Align=center>4 Normal Align=center>20 Normal Align=center>26350 Normal Align=center>2650 Normal Align=center>7.

26 Normal Align=center>25.

6 Normal Align=center>500 Normal Align=center>20 Normal Align=center>1.

8 Normal LINE-HEIGHT of · of Exactly" Align=center>Q /kJ: 15pt; TEXT-ALIGN: Center; Mso-line-height-rule: Exactly" Align=center>211.

09 Normal Align=center>166.

36 Normal Align=center>308.

6 Normal Align=center>157.

96 Normal Align=center>49.

9 Normal Align=center>83.

56 Normal Align=center>55.

7 Normal Align=center>163.

02 Normal Align=center>216.

11 Normal Align=center>108.

　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 　 of 68 　 notes: ① element diffuses mediumly in Fe3Al and 18-8 steel factor and diffuse activation can data is brought from document [7] . Heat temperature / ℃ (computation of A)t= 50min measured value is worth (A) heats the time of heat preservation of ℃ of influence T= 1040 of temperature / computation of Min (b) measured value is worth (the influence Normal Align=center> graph diffuses Normal Align=center> computation and actual measurement value compare Normal >normal > diffuses according to Fe3Al/18-8 interface reaction layer ply and heat the parameter of diffusion welding craft with the affirmatory and equal concern of time of temperature, heat preservation, can obtain the interface that has certain ply to diffuse reaction layer. In addition, fe3Al/18-8 interface diffuses the conceal time T0 with react the formation of the layer has certain. The interface diffuses the growth of reaction layer the rule makes clear, when reaction layer ply is certain, as heat of temperature T elevatory, conceal time T0 shortens. Accordingly, in obtain the interface that has appropriate ply to diffuse below the condition of reaction layer, rise heat temperature T while can reduce T of heat preservation time appropriately, can shorten apparently so weld time, improve work efficiency. Normal >normal >3 conclusion Normal >normal >(1) control heats temperature 1040 ℃ , 45~60min of heat preservation time, solder when pressure 15MPa, acquisition Fe3Al/18-8 interface diffuses the organization of reaction layer is pettier, EPMA analysis makes clear, fe3Al/18-8 interface diffuses the photograph structure that reaction layer forms basically has photograph of FeAl, Fe3Al, Ni3Al and α - Fe (Al) solid solution, these photograph structures are helpful for an interface of around element diffuse the formation that reachs reaction layer. Normal >(2) Fe3Al/18-8 interface diffuses the conceal time T0 with react the formation of the layer has certain, the growth of reaction layer follows parabola pattern, its ply X and heat the relation of temperature T and T of heat preservation time is X2=4.

5 × 10-4exp(-55.

7/RT)(t-t0) , according to this one rule, the choice of parameter of craft of OK and directive diffusion welding. CNC Milling