21 2 2011 2 Vol.21 No.2 The Chinese Journal of Nonferrous Metals Feb. 2011 1004-0609(2011)02-0384-08, ( 730050) XRD EBSD (ECAP) (99.9%) A 101 (40 ) TG376.3 A Grain orientation evolution and texture fluctuation effect of pure copper during equal channel angular pressing GUO Ting-biao, DING Yu-tian, YUAN Xun-feng, HU Yong (Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China) Abstract: The polycrystalline samples of pure Cu (99.9%, mass fraction) were processed at room temperature by equal-channel angular pressing (ECAP). The microstructure and its changing mechanism after ECAP were investigated by X-ray diffraction (XRD) and electron backscattered diffraction (EBSD). The results indicate that when the pure copper is extruded by route A, with the increase of strain, the original 101 texture decreases coupled with the grains refinement, and the distribution uniformity of copper is improved. With the increase of the fraction of high-angle grain boundaries (HAGBs), the peak of misorientation moves to the typical value (40 ), gradually becomes normal distribution, and the misorientation gradient decreases. The formation of texture shows a texture fluctuation effect when ECAP is a dynamic process, the direction and strength of which are closely related to the strain of the material. The texture fluctuation effect is the integrated reflection of crystal structure grain boundary character, aggregation state at a certain temperature and under the action of forces. The external force acting on crystal class then makes the segregation orientation change, in the process of internal stress transmited on the neighboring grain boundaries, the aggregation state is broken, which cause the new texture of the material interior to vanish or appear. Key words: equal channel angular pressing; electron back-scattered diffraction; grain orientation; grain boundary misorinetation distribution; texture fluctuation (SPD) [1] SPD (SB01200606) (2009-1-9) 2010-01-19 2010-06-01 13893243521 E-mail: dingyt@int.com
21 2 385 [2] ( ) [3] SPD 111 //ND( normal direction) FCC 111 //ND SPD [4] (ECAP) SPD [5] ECAP A B C B Ba Bc [6 8] (ECAP) ( ) [9] [10] ECAP [11 13] ECAP XRD EBSD ( )ECAP A 1 ECAP 1 2 MoS 2 YT071 100A 98 10 4 N 10 MPa 25 mm/s 1 ECAP Fig.1 Assembly drawing of ECAP die-set: 1 Installation board; 2 Location pole; 3 Location sheathing; 4 Outside sheathing; 5 Inside sheathing; 6 Mandril location board; 7 Crest slab; 8 Upper moulding board; 9 Bolt; 10 Mandril; 11 Installation board; 12 Pin T2 70 mm Φ=105 Ψ=37 600 # 800 # 1000 # 1200 # 2000 # EBSD 500 ml +250 ml + 250 ml +50 ml +5 g 20~35 4 V 6~8 min D8 ADVANCE X XRD EBSD Nordlys EBSD Channel 5 FEI TOUANATA400 70 (0.15~2 µm )
386 2011 2 600 µm 600 µm 4 (H) (Z)XRD 2 2 2.1 XRD 2 ECAP A 0 1 2 (111) 2 (111) (200) (220) 2 (111) (311) (222) 2 2 A 0 1 2 4 XRD Fig.2 XRD patterns of pure Cu ECAP by route A (H: Transverse; Z: Normal): (a) H, 0 pass; (b) Z, 0 pass; (c) H, 1 pass; (d) Z, 1 pass; (e) H, 2 passes; (f) Z, 2 passes; (g) H, 4 passes; (h) Z, 4 passes
21 2 387 4 (111) (200) 2.2 EBSD X [11] 3 ECAP 0 1 2 4 EBSD ( Euler ) 3 150 µm 1 50 150 µm 1 4 4(d) 4 ECAP A 0 1 2 4 {111} XO (Normal direction ND ) YO (Extrution direction ED) 4 1 ( A ) 2 A 4 ( B ) A B EBSD EBSD [13] SPD XRD ECAP 3 EBSD Fig.3 EBSD orientation maps of samples ECAP after different passes (sample surface parallel to extrusion axis): (a) 0 pass; (b) 1 pass; (c) 4 passes; (d) 4 passes
388 2011 2 ( ) 5(b) B ECAP ECAP 4 {111} Fig.4 {111} pole figures of samples ECAP after different passes (sample surface parallel to extrusion axis): (a) Initial condition; (b) 1 pass; (c) 2 passes; (d) 4 passes 3 3.1 5 ECAP 5(a) 3 [14] ( ) ( ) ECAP ( ) EBSD ( ) ECAP : 5 ECAP Fig.5 ECAP strain subarea(a) and two grains(b) with different orientations A (111) (200) (220) (311) 3
21 2 389 (111) (111) 6 ECAP 0 1 2 4 EBSD 6 101 2 001 101 6(d) 4 101 001 6 4 3 A ECAP 4 6 1 2 4 Fig.6 Inverse pole figures of samples in initial condition(a) and ECAP after 1 pass(b), 2 passes(c) and 4 passes(d) 3.2 7 ECAP 1 4 8 EBSD 7 7 Cu ECAP 0 1 4 8 Fig.7 Misorientation angle distribution of Cu samples ECAP after different passes by route A: (a) Initial; (b) 1 pass; (c) 4 passes; (d) 8 passes
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