在此實驗中所使用的Al-10at%Fe合金是由純鋁粉與純鐵粉均勻混合後經簡單的壓粉與燒結製程所製造。經燒結後的塊材再經由多道次摩擦攪拌製程製造鋁鐵合金。而經摩擦攪拌製程後Al-Fe合金可被細化到次微米尺度。由穿透式電子顯微鏡顯示含鐵的顆粒均勻散佈在鋁基材中且第二相的平均粒徑大小約100nm。且由X光繞射與能量散佈儀鑑定結果顯示，含鐵之第二相為Al13Fe4。而磨擦攪拌區有明顯的反應層在鐵顆粒周圍。此現象是因摩擦攪拌製程可在Al-Fe之間產生快速的反應所致。在本實驗中使用更高走速可以減少反應時間與反應熱，但低走速可使反應更完全。由實驗結果顯示低走速攪碎效果最好，可使顆粒有效被細化且均勻散佈在鋁基材中，進而提升機械性質。而更高的燒結溫度也會增加Al-Fe的反應。本研究利用了微硬度試驗，拉伸試驗與壓縮試驗來量測Al-Fe的機械性質。

In this study, billet of a binary Al-10at%Fe alloy was prepared from pure Al and Fe powders by the use of conventional press and sinter route. The sintered billet was then subjected to multiple passages of friction stir processing (FSP). After FSP, the structure of a binary Al-10at%Fe alloy can be refined to sub-micrometer scale. Transmission electron microscopy (TEM) showed that particles of Fe-containing phase were distributed uniformly in the aluminum matrix, and the mean size of these second phase particles was about 100nm. From the results of X-ray diffraction and energy dispersive spectroscopy (EDS), the Al-Fe second phase was identified as Al13Fe4. We also observed obvious reaction zone around iron particles in the friction-stirred zone. Apparently, a rapid in-situ reaction between Al and Fe had occurred in FSP. In order to reduce the reaction time and the heat input, the higher traversing speed was used. In addition, a higher sintering temperature was used to promote Al-Fe reaction. Furthermore, micro-hardness, tensile and compressive tests were performed to evaluate the mechanical properties of the Al-10at%Fe alloy fabricated by FSP.

Table of Contents

Chapter 1 Introduction........................................................................................1
Chapter 2 Literatures Review............................................................................3
2-1 FSW/FSP ………………………………………………………..…………..3
2-2 Advantages and applications of FSW/FSP………………………………3
2-3 Metal flow in FSW.........................................................................................5
2-4 Thermal history in FSW................................................................................7
2-5 Microstructure evolution in FSW………………………………………….9
2-6 Residual stress in FSW……………………………………………………10
2-7 Al-Fe alloys...................................................................................................12
2-8 Al-Fe alloy processed by Severe plastic deformation (SPD).....................12
2-9 Al-Fe alloys processed by ECAP…………………………………………13
2-10 Swelling behavior in reaction sintering of Al-Fe powders………….13
2-11 Interfacial reaction between molten Al and solid iron………………...15
2-12 Al13Fe4 structure……………………………………………………….....15
Chapter 3 Experimental Procedures………………………………………..17
3-1 Material preparation...................................................................................17
3-2 Friction stirred processing (FSP)…………………………………………17
3-3 Microstructure characterization…………………………………………17
3-4 Mechanical properties…………………………………………………….18
Chapter 4 Results………………………………………………………………..20
4-1 Effect of multiple FSP passes……………………………………………..20
4-2 Effect of tool traveling speed……………………………………………...24
4-3 Effect of sintering temperature…………………………………………...25
Chapter 5 Discussion……………………………………………………………27
5-1 Reaction between Al and Fe in FSP……………………………………………27
5-2 The formation of intermetallic phase………………………………………….27
5-2 Influence of tool travelling speed........................................................................28
5-3 Influence of sintering temperature…………………………………………….29
Chapter 6 Conclusion..........................................................................................31
References…………………………………………………………………………33




















List of Figures
Fig.2-1 Schematic drawing of friction stirred welding………………………………36
Fig.2-2 Metal flow pattern…………………………………………………………...37
Fig.2-3 Metallurgical processing zones developed during friction stir welding……..37
Fig.2-4 The material flow at advancing side when u = 2 mm/s, ω = 390 rpm……….38
Fig.2-5 The material flow at retreating side when u = 2 mm/s, ω = 390 rpm………..38
Fig.2-6 Average maximum temperature by FSW…………………………………….39
Fig.2-7 Macrostructural classification of the different regions generated by FSW….40
Fig.2-8 TEM micrographs of the different regions of the friction stir processed 7075 Al alloy; (a) specimen 1 with the corresponding SAD pattern, (b) a dark-field image from specimen 1, (c) specimen 2, (d) specimen 3, (e) specimen 4 and (f) specimen 5………………………………………………………………………………………41
Fig.2-9 The microstructure evolution during FSW/FSP……......................................42
Fig.2-10 EBSD maps showing the grain structures in the nugget zones in the thin plate welds; (a) at the centre and (b) near the bottom of the nugget in the 180 rpm low heat input weld, and (c) at the centre and (d) near the bottom of the nugget in the 450 rpm high heat input weld. In (e) and (f) the grain structure is shown at the top and bottom of the nugget. High and low angle boundaries are shown as dark and light lines…………………………………………………………………………………43
Fig.2-11 An example of a boundary misorientation distribution of the centre of the nugget zone from the low heat input (180 rpm). The dashed line shows the theoretical distribution for a random grain assembly…………………………………………….43
Fig.2-12 (a) Longitudinal and (b) transverse residual stresses as a function of lateral distance from the weld line…………………………………………………………..44
Fig.2-13 Residual stress results for the 6.3mm thick FSW AA2024 sheets. One sheet was welded untensioned, the other was tensioned to 70% tensile yield strength prior to welding………………………………………………………………………………44
Fig.2-14 DSC (a) and dilatometry (b) data obtained by heating a Fe–40Al mixture at a rate of 5 °C min−1……………………………………………………………………46
Fig.2-15 Thermal expansion profile of a Fe–40Al sample heated at a rate of 0.5 °C min−1………………………………………………………………………………...46
Fig.2-16 Fe-Al equilibrium phase diagram…………………………………………..47
Fig.2-17 Optical micrographs image in the interface layer…………………………..48
Fig.2-18 The EPMA analysis by BSE………………………………………………..49
Fig.2-19 The creaking and detachment of FeAl3…………………………………….49
Fig.2-20 Atomistic structure of an Al13Fe4 belonging to C2/m space group
viewed along (a) x//[1 0 0], (b) y//[0 1 0] and (c) z//[0 0 1] axes…………………….50
Fig.2-21 Pentagonal atom columns consisting of four layers………………………..51
Fig. 2-22 Schematic illustrations of the three different types of twins observable in the Al13Fe4 phase…………………………………………………………………………51
Fig.3 Demonstrate of the experimental procedures in this research…………………52
Fig.4-1 XRD pattern for 550oCsintering……………………………………………..53
Fig.4-2 XRD pattern by N=1 (45mm/min, 550oC sintering)………………………...53
Fig.4-3 XRD pattern by N=2 (45mm/min, 550oC sintering)………………………...54
Fig.4-4 XRD pattern by N=4 (45mm/min, 550oC sintering)………………………...54
Fig.4-5 BE image between BM and SZ, for N=2…………………………………….55
Fig.4-6 BE image between BM and SZ, for N=2…………………………………….55
Fig.4-7 SEI and BEI in SZ for N=2………………………………………………….56
Fig.4-8 BEI in SZ for N=2…………………………………………………………...57
Fig.4-9 SEI and BEI in SZ for N=4……………………………………………….....58
Fig.4-10 SEI and BEI in SZ for N=4………………………………………………59
Fig.4-11 BEI in BM (line scanning),for N=4………………………………………...60
Fig.4-12 EPMA analysis in base metal………………………………………………61
Fig.4-13 EPMA analysis in stir zone, after 2 passes (550oC).......................................62
Fig.4-14 EPMA analysis in stir zone, after 2 passes (550oC).......................................63
Fig.4-15 EPMA analysis in stir zone, after 2 passes (550oC)......................................63
Fig.4-16 EPMA analysis in stir zone, after 2 passes (550oC).......................................64
Fig.4-17 EPMA analysis in stir zone, after 2 passes (550oC)………………………...64
Fig.4-18 EPMA analysis in stir zone, after 4 passes (550oC)………………………...65
Fig.4-19 TEM micrograph at low magnification (after 4 passes, 550oC)……………66
Fig4-20 TEM micrograph at high magnification (after 4 passes, 550oC)……………66
Fig4-21 .Microstructure of the Al-rich grains in bright field images (a), together with a selected area diffraction pattern (SADP)(b)..............................................................67
Fig4-22 TEM micrograph at higher magnification (after 4 passes, 550oC) ................68
Fig4-23 The particle A accompanies with the light contract, which can be identified as [130] zone of Al13Fe4 (after 4 passes, 550oC)...............................................................69
Fig.4-24 The particle B, which can be identified as [130] zone of Al13Fe4 (after 4 passes, 550oC)………………………………………………………………………..70
Fig.4-25 The particle C, which can be identified as [010] zone of Al13Fe4 (after 4 passes, 550oC)..............................................................................................................71
Fig.4-26 The particle D, which can be identified as [110] zone of Al13Fe4 (after 4 passes, 550oC)..............................................................................................................72
Fig.4-27 (a) The bright field image (BFI) of Al13Fe4 grain (b) The dark field image (DFI) of Al13Fe4, the grain size~150nm. (after 4 passes, 550oC)….............................73
Fig.4-28 The bright field image (BFI) of Al grain (b) The dark field image (DFI)
Of Al, the grain size~1μm. (after 4 passes, 550oC)…………………………………74
Fig4-29 The dark field image (DFI) of aluminum (after 4 passes, 550oC)…………..75
Fig4-30 Variation of Vickers micro-hardness across the cross section of stirred zone for specimens after various FSP passes (45mm/min, 550oC sintering)………………76
Fig4-31 Stress-strain curves for different passes FSP specimens at low traveling speed (45mm/min, 550oC sintering), for tension…………………………………………...77
Fig4-32 Stress-strain curves for different passes FSP specimens at low traveling speed (45mm/min, 550oC sintering), for compression……………………………………...78
Fig4-33 The microstructure after eight passes (N=8), (a) at low magnification (b) at high magnification……………………………………………………………………79
Fig4-34 The microstructure in medium traveling speed (65 mm/min) after 2 FSP passes (a) between the stirred zone and base metal (b) in stirred zone………………80
Fig4-35 The microstructure during high traveling speed (85 mm/min) after 4 passes…………………………………………………………………………………81
Fig4-36 Variation of Vickers micro-hardness across the cross section of stirred zone for specimens at high traveling speed after various FSP passes (65mm/min, 550oC sintering)……………………………………………………………………………...82
Fig.4-37 Stress-strain curves for different passes FSP specimens at high traveling speed (65 mm/min, 550oC sintering), for tension……………....................................83
Fig.4-38 XRD pattern after 600oC sintering………………………............................84
Fig.4-39 The microstructure in595oC sintering speciment after 2 FSP passes (a) between the stirred zone and base metal (b) in stirred zone………………………….85
Fig.4-40 The microstructure in595oC sintering speciment after 4 FSP passes (a) between the stirred zone and base metal (b) in stirred zone………………………….86
Fig.4-41 EPMA analyzed in 604oC sintering specimen……....................................87
Fig.4-42 Variation of Vickers micro-hardness across the cross section of stirred zone for specimens during 600oC sintering after various FSP passes (85mm/min, 600oC sintering)…...................................................................................................................88
Fig.4-43 Stress-strain curves for different passes FSP specimens at high sintering temperature (85 mm/min, 600oC sintering), for tension………………………..........89
Fig.5-1 Schematic illustrations of the reaction for Al-Fe system by the plasma synthesis method……………………………………………………………………..90
Fig.5-2 The microhardness across the cross section of stirred zone for specimens after various traveling speed (45mm/min, 65mm/min and 85mm/min)…………………...91
Fig.5-3 Stress-strain curves for different traveling speed (45mm/min and 65mm/min)…………………………………………………………………………...91
Fig.5-4 The microhardness across the cross section of stirred zone for specimens after different sintering temperature (550oC and 600oC)…………………………………..92
Fig.5-5 Stress-strain curves for different sintering temperature (550oC and 600oC)...92














List of Tables
Table 4-1 Thermocouple measurement positioned as close as possible to nugget zone…………………………………………………………………………………..39
Table 4-2 Mean grain size by various passes of ECAP………………………………45
Table 4-3 Tension test properties by ECAP………………………………………….45
Table 4-4 Phase reactions in Fe-Al phase diagram…………………………………..47
Table 4-5 Thermodynamic constants for the intermetallic from in Fe-Al binary system………………………………………………………………………………...48

[1] Tjong SC, Ma ZY / Materials Science and Engineering 2000:29:49
[2] Thomas WM, Nicoholas ED, Needham JC, Church MG, Templesmith P, Dawes CJ, Friction Stir Butt Welding G.B. Patent Application No. 9125978.8, December 1991; US Patent No. 5460317, October 1995.
[3] Berbon PB, Bingel WH, Mishra RS, Bampton CC, Mahoney MW. Scripta Mater 2001:44:61.
[4] Hsu CJ, Kao PW, Ho NJ, Scripta Mater 2005:53:341.
[5] Kim YW, Griffith WM, editors, Dispersion Strengthened Aluminum Alloys, TMS, Warrendale, PA, 1988.
[6] Senkov ON, Froes FH, Stolyarov VV, Valiev RZ, Liu J. Nanostr Mater. 1998:10:691.
[7] Su JQ, Nelson TW, Sterling CJ. Scripta Mater 2005:52:35.
[8] Mishra RS, Mahoney MW, McFadden SX, Mara NA, Mukherjee AK. Scripta Mater 2000:42:163.
[9] Mishra RS, Ma ZY, Charit I, Mater. Sci. Eng. A 2002:341:307.
[10] W. J. Arbegast, TMS, 2003
[11] Heurtier P, Desrayaud C, Montheillet F. Mater Sci Forum 2002:396-402:1573.
[12] Zhang HW, Materials Science and Engineering A 2005:403:340
[13] Colligan K. Welding J. 1999:78(7):229
[14] Reynolds AP. Sci. Technol. Welding Joining 2000:5:120
[15] Park C, Sato S, Kokawa H, Metallurgical and Materials Transactions A 2003:34A:987
[16] Cho JH, Materials Science and Engineering A 2005:398:146
[17] Hassan KAA, Prangnell PB, Norman AF, Price DA, Williams SW, Science and Technology of Welding and Joining 2003:8:4257
[18] Frigaad O, Grong O, Midling OT, Metall. Mater. Trans. 2001:A32:1189
[19] Attallah MM, Salem HG/ Materials Science and Engineering A 2005:391:51
[20] Hassan KAA, Acta Materialia 2003:51:1923
[21] Peel M, Acta Materialia 2003:51:4791
[22] Staron P, Physica B 2004:350: e491
[23] Yaney DL, Nix WD, Metall Trans A 1987:18A:893.
[24] Mukhopadhyay DK, Suryanarayana C, Froes FH. Metall Mater Trans A 1995:26A:1939.
[25] Ivanisenko YV, Korznikov AV, Safarov IM, Valiev RZ, NanoStructured Materials 1995:6:433-436
[26] Senkov ON, Froes FH, Stolyarov VV, Valiev RZ, Liu J, Scripta Materialia: 1998:10:1511-1516
[27] Stolyarov VV, Materials Science and Engineering 2003:A357:159
[28] Gedevanish S, Dee SC, Materials Science and Engineering A 2002:352:163
[29] Kang HZ, Hu CT, Materials Chemistry and Physics 2004:88:264
[30] Hu CT, Lee S, Materials Science and Engineering A 2002: 329–331:69
[31] Metals Handbook, ASM International, 1992:63,10th Edition
[32] Bouche K, Barbier F, Coulet A, Mater. Sci. Eng. A 1998:249:167
[33] Shahverdi HR, Ghomashchi MR, Shabeatari S, Hejazi J, Journal of Materials Processing Technology 2002:124:345
[34] Yoneyama N, Materials Science and Engineering A 2003:350:117
[35] Saito K, Materials Science and Engineering 2000:294-296: 279
[36] Black PJ, Acta Crystallogr. 1955:8:43.
[37] Fung KK, Zou XD, Yang CY, Philos. Mag. Lett. 1987:55:27.
[38] Bhattacharya P, Ishihara KN, Chattopadhyay K, Materials Science and Engineering A 2001:304-306:250
[39] Lee JM, Kang SB, Sato T, Tezuka H, Kamio A, Materials Science and Engineering A 2003:362:257
[40] Shahverdi HR, Ghomashchi MR, Shabestari S, Hejazi J, Journal of Materials Science 2002:37:1061