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1 Journal of Korean Powder Metallurgy Institute DOI: /KPMI ƒ w Fe œ w Cu wy SPS (I) I. ƒ wy y Á xá½ Á½ *Á½{ a w œw, a w» gœ Production of Fe Amorphous Powders by Gas-atomization Process and Subsequent Spark Plasma Sintering of Fe Amorphous-ductile Cu Composite Powders Produced by Ball-milling Process (I) I. Gas Atomization and Production of Composite Powders Ho-Jin Ryu, Jae-Hyun Lim, Ji-Soon Kim, Jin-Chun Kim* and H. J. Kim a School of Materials Science & Engineering, University of Ulsan, Ulsan, , Korea a Eco Functional Materials Team, Korea Institute of Industrial Technology Songdo-dong, Yeonsoo-gu, Incheon, , Korea (Received July 6, 2009; Revised August 3, 2009; Accepted August 19, 2009) Abstract Fe based (Fe 68.2 C 5.9 Si 3.5 B 6.7 P 9.6 Cr 2.1 Mo 2.0 Al 2.0 ) amorphous powder, which is a composition of iron blast cast slag, were produced by a gas atomization process, and sequently mixed with ductile Cu powder by a mechanical ball milling process. The experiment results show that the as-prepared Fe amorphous powders less than 90 μm in size has a fullly amorphous phase and its weight fraction was about 73.7%. The as-atomized amorphous Fe powders had a complete spherical shape with very clean surface. Differential scanning calorimetric results of the as-atomized Fe powders less than 90 μm showed that the glass transition, T g, onset crystallization, T x, and super-cooled liquid range ΔT=T x T g were 512, 548 and 36 o C, respectively. Fe amorphous powders were mixed and deformed well with 10 wt.% Cu by using AGO-2 high energy ball mill under 500 rpm. Keywords : Amorphous powders, Gas atomization, Ball milling process, Composite powders 1. w 1960 Au 75 Si 25 w þƒ z Allied Signal ƒ Metglass yw w š w t y w ƒ y w, 1990 w w p ƒ š [1, 2]. j w (Bulk Metallic Glass, BMG) w ƒ y w 1 GPa Al w w y w. þƒ», ƒ w x Ì 0.2 mm w q y v j(flake), y w [3], jš,», x. w û x j» y w *Corresponding Author : [Tel : ; jckimpml@ulsan.ac.kr] 316

2 ƒ w Fe œ w Cu wy SPS (I) 317 Table 1. Chemical compositions and thermal properties of Fe based amorphous powders. (at%) Component (Atomic %) Tg( o C) Tx( o C) ΔTx( o C) ΔH(J/g) Fe 66.8 C 7.4 Si 3.5 B 6.7 P 9.5 Cr 2.1 Mo 2.0 Al Fe 66.7 C 7.7 Si 3.5 B 6.6 P 9.5 Cr 2.1 Mo 2.0 Al Fe 68.3 C 5.9 Si 3.5 B 6.7 P 8.8 Cr 2.2 Mo 2.5 Al Fe 68.2 C 5.9 Si 3.5 B 6.7 P 9.6 Cr 2.1 Mo 2.0 Al Fe 64.3 C 6.9 Si 2.5 B 6.7 P 8.8 Cr 2.2 Mo 2.1 Al š w x w x/». û x w j» ü Á 2 w yw [4, 5]. 2 gq wy w.» ü 2 ww œ yƒ w. 2 gq y w yw,» s [6, 7]. ù, ƒ w œ 2 yww œ, yw- x- e. yw œ 2 k - w p ƒ w, œ w [8-11]. ƒ Fe wš, œ mw Cu wyw. z p w» w v mw š Fe- Cu w wš, x p š w. Fe ƒ w, (slag) w [12]. 2. x 2.1. Fe,» Fe w w ƒ, ew t ƒ, [13]. t 1 w Fe, x ƒ w Fe 68.2 C 5.9 Si 3.5 B 6.7 P 9.6 Cr 2.1 Mo 2.0 Al 2.0 kw. (ΔT x ) ΔT g 517 o C, T x 558 o C, T x 41 C ƒ o ΔT x š. t 1 Fe w t ùkü, at% y w ùkü, k Fe 81.0 C 1.5 Si 2.1 B 1.5 P 6.3 Cr 2.3 Mo 4.1 Al 1.2. Fe 81.0 wt% š,»k (metalloid) C, Si, B, P Mo, Al. k y œ ƒ kw. Fe w C, Si, B, P w w» þƒ ƒ ƒ w. Kim [6, 7]» w, œ», 1350~1450 o C, 40 bar ƒ w Cu» wy w y (558 o C) (1083 C) ƒ Cu o kw. p Cu w š, yw» 2 w p w v ƒ w. 1 w Cu x FE- SEM. Cu š w y. s³ 40 μm 100 μm w y. ƒ Fe w Cu 5~15 wt%¾ ƒw w w. wy 3 yw»(turbular mixer) š (AGO-2, Planetary ball mill) 2ƒ w. Turbular yw» 3 z p

3 318 y Á xá½ Á½ Á½{ Fig. 2. Volume comparison of the as-synthesized powder. Fig. 1. FE-SEM image of the raw Cu powder. s yw w w, Fe q ³ w ywy ww œ š q. AGO-2» w yƒ ƒ w š œ. wy w 1:10 w, wy y w w» w y Ar» ww. wy xk w Ÿwx, x (Field Emission Scanning Electron Microscope, FE-SEM), X z (X-Ray Diffraction, XRD) Ÿ»(Energy Dispersive X- ray Spectroscopy, EDS) w. 3. x 3.1. ƒ w p ƒ w y y y (sieving) XRD w. ƒ μmj» l nmj» ¾ w j» w. w j» þƒ ƒ», þƒ y ƒ yw», y w» w w. w q (flake) w z, j» y w» w +150 μm, μm, μm, μm, μm, -43 μm ( z ƒƒ 1, 2, 3, 4, 5, 6 ) w y w, ƒ x w. 2 ƒ z v w» w j». l j» y 1 6 ¾ ùkü, 1 ƒ v, z 4, 5 w. 1 q x w vƒ ƒ j. j» x ƒ q x w 4, 5 p ùkü ƒ w ww š w. t 2 ƒ t ùkü, 3 v ù kü. t 2 3 r ƒ y q w. 150 μm 9.5%, w 90.5%. š μm 16.8%, w Table 2. Distribution result of the powder synthesized by gas atomization Sieve Mesh Size (μm) Average Size (μm) Weight (Powder, g) Rate (%) ~100 ~ ~ ~ ~ ~ ~200 90~ ~325 75~ ~ 43~ Journal of Korean Powder Metallurgy Institute

4 ƒ w Fe œ w Cu wy SPS (I) 319 Fig. 3. Cumulative distribution of the as-synthesized powder. 73.7% y w. 100 μm w y w. 4 ƒ j» x x w. r xyƒ w, 4 (a) (b) s³ ƒ 100 μm j»» ƒ œ š x w ƒ. ù (c) (d) 100 μm w x š. 5 j» ü ù kü. (a) 150 μm j», 400 μmƒ q (flake) x ƒ. ƒ,» þƒ wš ü t w þƒ q š. (b) (c) ( , μm) ü»œ y ƒ ü û» ƒ ùƒ w þƒ. (d) ( μm)» œ ¼ w, (b), (c) j»œ, x x ƒ y w. -75 μm w (e) (f) Fig. 4. Images of the as-prepared Fe amorphous powders.

5 320 y Á xá½ Á½ Á½{ Fig. 5. Cross section images of the as-prepared Fe amorphous powders. x š, w w x y w. 6 j» w z, y XRD w w w w vj(halo peak)ƒ x y w, yƒ š q w. 2, 3 ( , μm) w vj(halo peak) ƒ y vj x. Fe 3 C y FeB y [12]. w 4 w q w. 1» w q x» w, v ƒ j», 9.5% w. ƒ e w þƒ p ƒ ù, ƒ wš q x» x Journal of Korean Powder Metallurgy Institute

6 ƒ w Fe œ w Cu wy SPS (I) 321 Fig. 6. XRD graph of the as-prepared Fe amorphous powders. w p Fe p w (t 1) w. 7 8 Fe DSC. 7 (a), (b), (c) ƒƒ 2, 4, 6 DSC v 8 (a), (b), (c) (Glass transition temperature, T g ) (ΔT x ) y w» w v (200~600 C) ùk o ü. t w k p t ùkü. p ùkü 4 T g 512 o C, T x 548 o C, ΔT x 36 o C. 6 T g 514 o C, T x 548 o C, T x 34.» T g 517 o C, T x 558 o C, ΔT x 41 C w o T g, T x 10 C o shift š, ΔT x w» p ƒ j ( ) w š, 7, 8 ƒ w Fig. 7. DSC graphs of the as-prepared Fe amorphous raw powders. Fig. 8. Magnified DSC graphs of the as-prepared Fe amorphous raw powders.

7 322 y Á xá½ Á½ Á½{ Table 3. Thermal behaviors of the as-prepared Fe amorphous powders Sample Temp T g T x ΔT x Bulk (Ref. 13) μm μm w» ƒ q. ƒ w x ƒœ ƒ w» ΔT x ƒ z x ƒœ w. w ΔT x ƒ 35 o C ü, z x/ w ƒ q wy p 9 wy wy FE-SEM. (a) Fe x r x š y w. (b) Turbular mixer w 12 yww. 1 y Cu q w 20~40 μm j» ƒ k ù, (agglomeration)(t ) y w. x Fe x š x x wš. (c) AGO-2 w 300 rpm 10 w y k w xk Cu q 20~30 μm j» y w. Turbular mixer w (b) AGO-2 š w Fe ƒ x/q (t Fig. 9. FE-SEM images of the as-milled Fe-Cu composited powders with different processes. Journal of Korean Powder Metallurgy Institute

8 ƒ w Fe œ w Cu wy SPS (I) 323 Fig. 10. FE-SEM images of the as-milled Fe-Cu composite powder with Cu contents (-43 μm, AGO-2, 500 rpm, 10 min, Ar atmosphere). ), ³ew x y. (d) AGO-2 w 500 rpm x w w. Cu (c) w x, ³e x (t )., Turbular mixer Fe x ù Cu wš, AGO-2, 300 rpm wyw x ³e x ƒ, š ƒw 500 rpm Cu Fe ³ w x ƒ y w. AGO rpm w Cu ƒ x ƒ AGO rpm ƒ ƒ x/ q. Fe Cu w ü» w Cu w w. Cu w w œ wù,» w w, w w» w x ww rpm ƒ x ùkü. Cu 5 wt.% x Cu j» 20~60 μm ƒ j y w, Cu 10 wt.% j» 10~40 μm w ƒ ³ w y w. Cu 15 wt% j» 20~50 μm ƒw w, q x ƒ y w. z Fe- Cu w SPS 10 wt% Cu ƒ ³ w q, w z» [13]. 11 w EDS. 11 (a), 11(b) 10 wt% Cu w ùkü.» Fe-C-Si-B-P-Cr-Mo-Al, EDS ƒ y w. EDS w» w. wr 500 rmp ³ w wy Fe- Cu 10 wt% w w Cu vj y w. 4. Fe wš,

9 324 y Á xá½ Á½ Á½{ Fig. 11. EDS results of the as-atomized Fe powder and 10 wt% Cu composite powder. p r. w w wy œ š Fe Cu w yw, z v ww w. 1. ƒ Fe 150 μm w x ƒ. j» y w μm j» y vjƒ, 90 μm w xkƒ ùkù y w. 2. ƒ y 90 μm w, w 73% y w. DSC T g 512 o C, T x 548 o C, ΔT x 36 C y w o. 3. wy p, Turbular mixer, AGO rpm, AGO rpm w, š x j û, Cu yw ƒw. 4. w wy r Cu 5wt% f, 15 wt% Cu Cu q x. Cu w 10 wt% ƒ ³ w s ƒ y w. 10 wt% Cu ƒ ³ w w q. j ù w w,. š x [1] A. Inoue: Acta Mater., 48 (2000) 279. [2] T. Masumoto: Materials Science of Amorphous Met- Journal of Korean Powder Metallurgy Institute

10 ƒ w Fe œ w Cu wy SPS (I) 325 als, Ohmu, Tokyo, (1982). [3] M. Hagiwara, A. Inoue and T. Masumoto: Metal Trans. A, 13 (1982) 373. [4] H. Fu, H. Zhang, H. Wang, Q. Zhang and Z. Hu: Scripta Mater., 52 (2005) 669. [5] C. C. Hays, C. P. Kim and W. L. Johnson: Mater. Sci. Eng. A, (2001) 650. [6] Y. J. Kim, B. K. Kim and J. C. Kim: Mater. Sci. Eng. A, 449 (2007) [7] J. C. Kim, Y. J. Kim. B. K. Kim, J. S. Kim: J. Korean Powder Metall. Inst., 13 (2006) 351. [8] J. S. Benjamain: Metall. Trans., 1 (1970) [9] J. S. Benjamain and R. C. Benn, editors.: Frontiers of high-temperature materials II. New York, INCO Alloys International, (1983). [10] J. S. Benjamain and T. E Vollin: Metall. Trans., 5G(1974) [11] C. C. Koch, O. B. Cavin, C. G. McMamey and J. O. Scarbrough: Appl. Phys. Lett., 43 (1983) [12] J. C. Kim, H. J. Ryu, J. S. Kim, J. C. Kim and H. J. Kim: J. Korean Powder Metall. Inst., in press (2009) (Korean). [13] H. Li and S. H. Lee: Mater. Sci. Eng. A, (2007) 189.