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1 Journal of Korean Powder Metallurgy Institute DOI: /KPMI ƒ w Fe œ w Cu wy SPS (II) II. w SPS p ½ *Á½ Á½{ a Á½ š b w œw, a w» gœ, b y œ Production of Fe Amorphous Powders by Gas-Atomization Process and Subsequent Spark Plasma Sintering of Fe amorphous-ductile Cu Composite Powder Produced by Ball-milling Process (II) II. SPS Behaviors of Composite Powders and their Characteristics Jin-Chun Kim, Ji-Soon Kim, H. J. Kim a and Jeong Gon Kim b 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 b Major of Image Printing, Incheon City College, Dowha-dong, Incheon, , Korea (Received July 15, 2009; Revised August 10, 2009; Accepted August 24, 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 Fe-based amorphous powders and the Fe-Cu composite powders were compacted by a spark plasma sintering (SPS) process. Densification of the Fe amorphous-cu composited powders by spark plasma sintering of was occurred through a plastic deformation of the each amorphous powder and Cu phase. The SPS samples milled by AGO-2 under 500 rpm had the best homogeneity of Cu phase and showed the smallest Cu pool size. Micro-Vickers hardness of the as-spsed specimens was changed with the milling processes. Keywords : Amorphous Fe powders, Gas atomization, Spark plasma sintering, Composite powders 1. y r (, metallic glass) l þƒ g w ƒ w w.» š šü, Ÿk ñ t p. š w t y w ƒ y w š, p 1 GPa j w (Bulk Metallic Glass, BMG) w ƒ y w [1-4]. j r w ƒ, š k w ü ƒ. šw ù x ûš š, *Corresponding Author : [Tel : ; jckimpml@ulsan.ac.kr] 326

2 ƒ w Fe œ w Cu wy SPS (II) 327 x z w k w sd t w. p þ (supercooled liquid region, y (T x ) (T g ) ) C o w x near net shaping w, x t x ww. ƒ þƒ», ƒ w x Ì 0.2 mm w q y v j(flake), y w [5]. p û x jš,», x. w wš y w š w x w x/» w. x ƒ w» ü Á 2 wyw 2 gq» wy w [6, 7]. x y w þ ü w š ƒw v (spark plasma sintering, SPS) ù j q (Microwave-induced Sintering) x œ š [8-10]. ƒ (slag) [11] Fe wš, œ mw Cu ³ w w w w z, v mw š Fe- Cu w wš w. œ w w [12], SPS œ z,» p š wš w. 2. x» yw w Fe-Cu w [12] x ƒ w ΔT x š y» SPS w. 10 C/min. o 500 MPa ƒw š w. SPS ü» œ(1 10 torr) w 2 r y w. m SPS š (graphite) w, š š ƒ wš,». ù, w 100 MPa w w. 500 MPa š y w (WC-10 wt.%co) ( 10 mm) w. SPS z x re j» w, 1 mm (sheet) yq w. x w T g 517 o C, T x 558 o C, ΔT x 41 C o 530 C o ww. 3 w, xz ü þ g z w. 3 mm y w, K-type w w. SPS q Ÿwx x (Field Emission Scanning Electron Microscope, FE-SEM) w w, y X z (X-Ray Diffraction, XRD) y w. SPS» p f (Micro-Vickers Hardness) d w w. ƒ 10z d w s³ w. 3. x 3.1. Fe w SPS p SPS p Fe 10 o C/mim, 530 C o. e yƒ 530 C 5 o w, 500 MPa š x ww. 1 j»ƒ Fe SPS œ w w r x. j»ƒ wš,

3 328 ½ Á½ Á½{ Á½ š Fig. 1. Morphology of the as-sintered Fe amorphous samples with size. (a) Gμm, (b) μm, (c) μm and (d) -43 μm Fig. 2. Optical micrographs of the surface area of as- SPSed samples. (Fe amorphous raw powders, 530 o C, 10 o C/ min, 5 min holding, 500 MPa, in vacuum) Fig. 3. Optical micrographs of the inner cross section of the as-spsed samples. (Fe amorphous raw powders, 530 o C, 10 o C/min., 5 min. holding, 500 MPa, in vacuum) Journal of Korean Powder Metallurgy Institute

4 ƒ w Fe œ w Cu wy SPS (II) 329 Fig. 4. XRD results of raw amorphous powder by SPS process. (Fe amorphous raw powders, 530 o C, 10 o C/min., 5 min. holding, 500 MPa, in vacuum) 530 o C SPSƒ yw. 2 r t w Ÿwx w. (a) ƒ j» 500 MPa wš t»œ w w. (b)»œ w y w ù»œj» (a). (c) x ù w e yƒ w,»œ, x ƒ y. 3 r ü ùkü. ƒ ü»œ j»ƒ w, 43 μm w w r»œ, yƒ 99%. (superplasticity) x ù T g -T x Fe q x w. SPS x x ü š, š kƒ, x w, y ƒ ywš, ( t w) ³x w ³ š. Fe x e yƒ. ù SPS, m ƒ v j š, š j, t. ù t þƒ y» SPS y»w,

5 330 ½ Á½ Á½{ Á½ š k. 4 Fe SPSw r XRD v. (a) 2 ( μm) 6 ùkü, ƒ yƒ k. SPS z y vj j y. ƒ yƒ» w w. ù p ƒ 4 ( μm), 5 ( μm), 6 (-43 μm) v Fe 3 C, FeB, Mo 4 P 3 Fe 2 P x w y vjƒ y., (b), (c), (d) w (halo) vj vjƒ y w SPS p 5 w w w Fe-5 wt.% Cu w SPS r w ùkü. r Turbular mixer yww (a) w. Turbular mixer Cu Fe ³ w yw» û». Cu ³ yw t w f Cu pool x w. AGO rpm» w yw (b) Fe x w š, Cu w y w. AGO rpm» w yw (c) (b) û, Cu. Cu pool x w š,»œ ƒ š, w. w Fe Cu yw ƒ w AGO rpm yw SPS p ƒ w. SPS Fe w Cu wy w, y. 6 wy r XRD v. v r (a) Fe 3 C, FeB, Mo 3 P 4, Fe 2 P y vj Cu vj ƒ ùkù. Fe Fig. 5. Cross section of as-sintered Fe-Cu sample by SPS. (-43 μm, Cu 5 wt.%, 530 o C, 10 o C/min, 5 min holding, 500 MPa, in vacuum) Cu ³ yw,» Fe w y vjƒ q. ù š (b), (c) Journal of Korean Powder Metallurgy Institute

6 ƒ w Fe œ w Cu wy SPS (II) 331 Fig. 6. XRD results of as-sintered Fe-Cu sample by SPS process. (-43 μm, Cu 5 wt.%, 530 o C, 10 o C/min, 5 min. holding, 500 MPa, in vacuum) vj j» w w 4 XRD y ƒ Fig. 7. Morphology of cross section of as-spsed Fe-Cu composite samples by SPS. (-43 μm, 10 o C/min, 530 o C, Holding 5 min, 500 MPa, in vacuum) û w. š Cu ³ w yw, v j» q

7 332 ½ Á½ Á½{ Á½ š. Cu ³ yw SPS y Fig. 8. Fractographs of the SPS amorphous Fe-ductile Cu composite samples. (-43 μm, 10 o C/min, 530 o C, Holding 5 min, 500 MPa, in vacuum) û, Cu ³ w»œ š w. 7 Cu 5, 10, 15 wt.% ƒ j AGO rpm w SPS r. r (a) Cuƒ ù, Cu w Fe ö x e y. Cu 10 wt.% wy k (b) (a), Cu ù ö j. Cu wyƒ w. Cu 15 wt.% wy k (c) (a), (b) ù, x x w. ù j Cu pool x w. Cuƒ n wy» Cuƒ ƒƒ Cu pool x w q. 8 7 q. Cu 5 wt.% wy k (a) r x ƒ x (t O) w. q œ r x q (t û) š, Cuƒ q œ q x (t ). Cu 10 wt% wy k (b) r (a) x xk w ö x Cu wy w w q, r Cu (t ). (b) q ƒ û, Cu q. Cu 15wt.% wyw (c) (a) (b) w x ƒ w ù Cu q ƒ (t )w Cu ƒ n q. 9 8 q Cu 10 wt.% Cu 15 wt.% y w. Cu 10 wt.% SPS w x Journal of Korean Powder Metallurgy Institute

8 ƒ w Fe œ w Cu wy SPS (II) 333 Fig. 9. Fractographs of the SPS amorphous Fe-ductile Cu composite samples. (-43 μm, 10 o C/min, 530 o C, Holding 5 min, 500 MPa, in vacuum) Cu ³ w. ù Cu 15 wt.% x Cu 10 wt.% j ù, Cuƒ j pool x w. Cu w SPS y w Cu 10 wt.% w Cu w Fe Cu w wy ƒ ƒ w, Cu w w ƒ ƒ w q. Cu w y XRD w w. 10 ƒ XRD ùk Fig. 10. XRD Results of as-spsed amorphous Fe-ductile Cu composite samples. ü v. v r Cu 5 wt.% wyw (a)» w y vjƒ y. Cu 10

9 334 ½ Á½ Á½{ Á½ š Fig. 11. Mirco-Vickers hardness of as-spsed samples. wt.% wyw (b) holo vj w, vj Cu vjƒ y. Cu 15 wt.%ƒ wy (c) Cu vjƒ ùkù, Cu w wy Cu w vjƒ. XRD mw Cu 10 wt.% wy ƒ w Fe Cu ³ w wyƒ š q w, AGO-2 SPS mw œ w Cu 10 wt.%ƒ ƒ w š q r» p 11 wy œ w Fe-5 wt.%cu w SPS ùkü. Fe w 1530 Hv ƒ š. Cu ƒw, Cu w w. w wy ƒ ùkù. œ w x Cu ƒ w wy w». Turbular mixingw wyw r Fe w r 10~80 Hv û.» w Turbular mixing w wy x ƒ ƒ š, Cu ³ yw Fe j w, Fe w w w q. AGO-2 w 300 rpm wyw w Turbular mixingw w r w w y w. wy š Fe x Cu wy w. j» w y j» q ù x š, w Cu ³ w yw ü Cu š d k q. AGO-2 w 500 rpm wy w w AGO rpm wy w w r w w, 1300 Hv ƒ y w. wy x y SPS 500 rpm x w» q. ù 300 rpm 100 û, d Cu yw ƒ ³ w» Fe Cu wy d AGO rpm ƒ ww q. 4. Fe wš, p SPS w y r. w w wy œ š Fe Cu wy w w SPS p w. 1. wy SPS e w. Fe w j»ƒ»œ j»ƒ, w wš x w e y y w. 2. SPS t / š Fe 3 C, FeB, Mo 3 P 4, Fe 2 P vjƒ y. Cu ƒ Cu 10 wt.%ƒ ƒ, ü w Cu ƒ y w. 15 wt.% Cu w w Cu vjƒ Journal of Korean Powder Metallurgy Institute

10 ƒ w Fe œ w Cu wy SPS (II) 335 ùkù y w. 3. SPS d œ Cu ƒ yw. SPS w 1530 Hv ƒ ù, Cu ƒ w. wy œ AGO2-500 rpm 1300 Hv ƒ û ƒ ù, Cu ³,»œ w l ƒ w w y p ƒ y w. j Áù w w,. š x [1] P. Duwez: Progress in Solid state chemistry, 3 (1967) 377. [2] P. K. Rastogi and P. Duwez: J. Non-crystalline Solids, 5 (1970) 1. [3] W. L. Johnson: Current Oponion in Solid State and Materials Science, 1 (1996) 383. [4] A. Inoue: Acta Materialia., 48 (2000) 279. [5] M. Hagiwara, A. Inoue and T. Masumoto: Metal Trans. A, 13 (1982) 373. [6] H. Fu, H. Zhang, H. Wang, Q. Zhang, and Z. Hu: Scripta Mater., 52 (2005) 669. [7] C. C. Hays, C. P. Kim and W. L. Johnson: Mater. Sci. Eng. A, (2001) 650. [8] Y. J. Kim, B. K. Kim and J. C. Kim: Mater. Sci. Eng. A, 449 (2007) [9] J. C. Kim, Y. J. Kim. B. K. Kim and J. S. Kim: J. Korean Powder Metall. Inst., 13 (2006) 351G(Korean). [10] D. V. Louzguine-Luzgin, G. Q. Xie, S. Li, A. Inoue, N. Yoshikawa, K. Mashiko, S. Taniguchi and M. Saito: J. Alloys and Compounds, 483 (2009) 78. [11] H. Li and S. H. Lee: Mater. Sci. Eng. A, (2007) 189. [12] H. J. Ryu, J. H. Lim, J. S. Kim, J. C. Kim and H. J. Kim: J. Korean Powder Metall. Inst., In press (2009) (Korean).