- Email: [email protected]
Texture transformation in an extruded magnesium alloy under pressure
Materials Science & Engineering A 582 (2013) 63–67
Contents lists available at SciVerse ScienceDirect
Materials Science & Engineering A journal homepage: www.elsevier.com/locate/msea
Rapid communication
Texture transformation in an extruded magnesium alloy under pressure D. Sarker, D.L. Chen n Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3
art ic l e i nf o Article history: Received 8 May 2013 Accepted 18 June 2013 Available online 26 June 2013 Keywords: Magnesium alloy Texture Twinning Orientation distribution function Compressive deformation
a b s t r a c t ̄ 0〉 ̄ and {0001} Extruded AM30 magnesium alloy showed two types of initial basal textures {0001}〈211 〈101̄0〉. Compressive deformation along extrusion direction resulted in their vanishing and the formation of {1̄21̄0}〈0001〉 and {011̄0}〈0001〉 textures, indicating that the c-axes always rotated towards the anticompression direction due to extension twinning. & 2013 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
As the lightest metallic structural material, magnesium alloys are promising for the application in the transportation industry to reduce vehicle weight and fuel consumption [1]. However, their widespread application is limited by the poor room temperature formability and strong anisotropy, which are mainly due to the development of crystallographic texture with basal planes of most grains aligned parallel to the rolling/extrusion direction. A tensile or compressive load along the c-axis of a hcp unit cell may cause the formation of extension or contraction twins, leading to the re-orientation of basal planes by ∼861 and ∼561, respectively, and contributing to the texture evolution [2,3]. The anisotropy in the mechanical properties results from a combination of initial texture and twin formation. For example, the forming behavior of magnesium alloys depends on the initial texture, processing condition and deformation temperature where slip and twinning played a vital role in the texture evolution [4,5]. The texture component in an AZ31 magnesium alloy also changed during tensile loading [6]. It is unclear what texture components are present and how they change in an extruded AM30 magnesium alloy during compression. The purpose of this study was, therefore, to identify the texture components and their evolution with increasing compressive strain in AM30 magnesium alloy.
Compression tests using computerized Instron machine at a strain rate of 1.25 10–4 s−1 were performed up to failure and several intermediate strains with cylindrical specimens (Φ5 mm 8 mm) where compression axis was parallel to ED. The deformed samples were cut along the compression axis, cold-mounted, and polished up to 1 μm diamond paste. Texture was determined using a PANalytical X-ray diffractometer by measuring incomplete pole figures between Ψ¼0–751 using Cu-Kα radiation at 45 kV and ̄ 40 mA. Five pole figures ({0001}, {101̄0}, {1011}, {112̄ 0}, {101̄3}) were used to calculate the orientation distribution function (ODF) using the MTEX software. Defocusing due to the rotation of sample holder was corrected using experimentally determined data from the diffraction of magnesium powders. Bunge notations of the Euler angles (φ1 Φ φ2) were used to represent the ODF.
n
Corresponding author. Tel.: +1 416 979 5000x6487; fax: +1 416 979 5265. E-mail address: [email protected] (D.L. Chen).
0921-5093/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msea.2013.06.048
3. Results and discussion The microstructure of the extruded AM30 alloy is shown in Fig. 1(a), consisting of a mix of large and small twin-free grains. The initial texture of this material, shown in Fig. 1(b), exhibited basically strong basal textures with a maximum intensity of 8.6 multiples of random distribution (MRD). The presence of strong concentration of (0001) poles with about 201 tilting towards the ED, along with (101̄0) poles towards both ED and TD, indicated that most of the grains with basal {0001} and prismatic {101̄0} planes were approximately parallel and perpendicular to the ED, respectively. Based on these results, a schematic diagram could be plotted in Fig. 1(c), where a specimen was
64
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
Extrusion direction
ED
TD
ND
ED
TD Fig. 1. (a) Microstructure, (b) (0001) and (101̄0) pole figures of the extruded AM30 magnesium alloy, (c) schematic diagram illustrating the relationship between the compression axis and c-axis of the crystals.
400
True stress, MPa
oriented with its cylindrical axis aligned parallel to the ED and the c-axis of the hcp unit cell was almost perpendicular to the ED. The true stress–true strain response of the sample is shown in Fig. 2, where the compressive yield strength was obtained to be 71 73 MPa, which was considerably lower than the tensile yield strength of ∼189 MPa [7]. The curve in Fig. 2 appeared peculiarly, relative to the normal tensile or compressive stress–strain curve of cubic metals. This was attributed to the occurrence of twinning in stage A and subsequent twin-dislocation interactions during compression [8]. The change of texture during compression is shown in Fig. 3 for several strain levels indicated by the vertical dashed lines in Fig. 2. At a strain of 1.5%, basal (0001) poles showed some extent of split of intensities from center towards radial direction (RD) with weak intensities along the ED, while prismatic (101̄0) poles with a moderate intensity were oriented towards ED, as shown in Fig. 3(a). More rotations of basal planes towards ED and prismatic planes towards the center were obvious with increasing strain level from 1.5% to 4.3% to 8.4% (Fig. 3(a)–(c)). The basal planes of further more
C
300
200 B 100
0
A A
0
3
6
9
12
15
18
True strain, % Fig. 2. A typical compressive true stress–true strain curve of AM30 magnesium alloy, where A, B and C indicate the strain hardening stages.
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
65
Fig. 3. (0001) and (101̄0) pole figures obtained from the compressed samples at a strain amount of (a) 1.5%, (b) 4.3%, (c) 8.4%, and (d) 12.9%.
grains were rotated to ED after 12.9% strain as indicated by the increasing maximum intensity from 12 to 16 MRD, while the prismatic planes were oriented in-between the center and RD, as shown in Fig. 3(d). To better understand the evolution of texture components, ODF was presented in a Euler space of 01≤φ1≤901,
01≤Φ≤901 and 01≤φ2≤601 as the alloy has hexagonal crystal symmetry. The texture change during compression at strain amounts of 0%, 4.3% and 12.9% is shown in Fig. 4(a), represented by the ODF sections at φ2 ¼01 and φ2 ¼301 from which the main texture components in hcp materials could be distinguished [6,9,10].
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D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
Strain=0%
Strain=4.3%
Schematic ODF
Strain=12.9%
1 1
A
C
D
B
1
D
25
A (90 20 0) B (90 20 30)
20
D {0110}<0001>
C (90 90 0)
f(g), M.R.D
D (90 90 30) 15
10
C { 1210}< 000 1>
5
A {0001}<2110> B {0001}<1010>
0 0
3
6
9
12
15
Strain, % Fig. 4. (a) ODF sections at φ2 ¼ 01 and φ2 ¼ 301, from the samples strained at 0%, 4.3% and 12.9%, and (b) the change of intensity of main texture components with the strain.
In the ODF sections several major components marked as A, B, C and D can be clearly identified, with the corresponding Euler angles given in Table 1. The undeformed alloy showed two types of basal ̄ 0〉 ̄ at orientation A(90, 20, 0) and texture components {0001}〈211 ̄ at orientation B(90, 20, 30), with their basal planes {0001}〈1010〉 being 7201 towards the ED as indicated by Φ¼201 while φ1 ¼901. A salient change in ODF at different strain levels was observed with respect to the undeformed alloy (Fig. 4(a)). That is, both texture ̄ 0〉 ̄ and B{0001}〈1010〉 ̄ disappeared, which components A{0001}〈211 ̄ were replaced by the formation of texture components C{1̄210} ̄ 〈0001〉 and D{0110}〈0001〉 at orientations (90, 90, 0), and (90, 90, 30), respectively, with increasing strain up to 12.9%. The change of components A to C in the ODF section of φ2 ¼01 and components B to D in the section of φ2 ¼301 with increasing strain indeed reflected a rotation of c-axes from an orientation of 7201 towards ED to that parallel to ED. This was equivalent to rotating the c-axes of most grains against the “push”. To quantify the change of these texture components, their intensity (f(g)) as a function of compressive strain was evaluated and plotted in Fig. 4(b). Clearly, components A and B rapidly faded away, while components C and D increasingly intensified. In the later stage of compressive deformation, the intensity of component D became higher than that of component C. This is likely related to the slightly higher density of component B
Table 1 Main texture components identified from Euler angles. Euler angles (φ1 Φ φ2)
(h k i l) [u v t w]
A (90, 20, 0) B (90, 20, 30) C (90, 90, 0) D (90, 90, 30)
̄ ̄0〉 7 201 towards ED {0001}〈211 ̄ 7 201 towards ED {0001}〈1010〉 {1̄21̄0}〈0001〉 {011̄0}〈0001〉
(8.8 MRD), as compared with that of component A (8.2 MRD), since component B subsequently changed to component D during compressive deformation. Similar results in an extruded AZ31 alloy were also reported in [6], where the intensity of component D was higher than that of component C. The observed change in the texture components can give us useful information about the deformation mode during compression. Based on the assumption that the intensifying of a texture component is at the expense of some other components, the development of components C and D can be associated with the weakening of components A and B. Such a rapid and large orientation change cannot be achieved by slip, but is possible by twinning [6,9,11,12]. The {101̄2} extension twinning has been
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
observed to play a predominant role in the texture evolution in the deformation of magnesium alloys [11,12], which was also responsible for the tension and compression anisotropy [13–15]. The initial components A and B with the c-axes of most grains nearly perpendicular to the ED (Figs. 1(b) and 4(a)) were favorably oriented for the activation of extension twinning when compressed along the ED (Fig. 1(c)). The occurrence of this type of twinning induces an 86.31 rotation of the basal plane or c-axis [2], so that the activation of {101̄2} twinning would satisfy the large orientation change of texture components A-C and B-D. The occurrence of abundant extension twinning in the extruded magnesium alloys, e.g., AM30, has been observed in [7,8,16]. Therefore, the evolution of texture components in the extruded magnesium alloy is predominantly related to the twinning. Additionally, as reported in [6,9,10], since the interplanar angle between components C and D is 301, the rotation of c-axes of most grains towards against the compression was anticipated to be also associated with the dislocation glide involving the twindislocation interactions and twin–twin interactions during deformation [8,16]. Further studies in this aspect are needed, e.g., by using atomic scale modeling and in-situ high-resolution transmission electron microscopy to observe the migration of twin boundaries during plastic deformation [17].
4. Conclusions The present study demonstrates that the compressive deformation along ED in AM30 extruded magnesium alloy led to a remarkable change in texture components. Both types of initial ̄ ̄0〉 and {0001}〈101̄0〉 were basal texture components {0001}〈211 observed to fade away, while {1̄21̄0}〈0001〉 and {011̄0}〈0001〉 texture components intensified with increasing compressive strain. Such texture changes revealed that the c-axes of hcp unit cells of most grains inside the material were always rotated towards against “push” or compression, mainly due to their 86.31 re-orientations stemming from extension twinning.
67
Prime novelty statement Two types of initial basal textures are identified in a recently developed AM30 extruded magnesium alloy. Both initial texture components disappear during compressive deformation, which are transformed into two new types of texture components, with the c-axes of hcp unit cells in most grains rotated towards the anticompression direction due to the re-orientations from extension twinning. Acknowledgments The authors would like to thank NSERC, PREA, NSERC-DAS Award, and AUTO21 for providing financial support. The authors also thank, Dr. A. Luo, Dr. R. Tandon and Dr. B. Davies for providing test materials, and Q. Li, A. Machin, J. Amankrah, and R. Churaman for assisting in the experiments. References [1] T.M. Pollock, Science 328 (2010) 986–987. [2] F.A. Mirza, D.L. Chen, D.J. Li, X.Q. Zeng, Mater. Sci. Eng. A 575 (2013) 65–73. [3] B.H. Lee, S.H. Park, S.G. Hong, K.T. Park, C.S. Lee, Mater. Sci. Eng. A 528 (2011) 1162–1172. [4] H.L. Kim, W.K. Bang, Y.W. Chang, Mater. Sci. Eng. A 552 (2012) 245–251. [5] Z. Zachariah, S.S.V. Tatiparti, S.K. Mishra, N. Ramakrishnan, U. Ramamurty, Mater. Sci. Eng. A 572 (2013) 8–18. [6] S.B. Yi, C.H.J. Davies, H.G. Brokmeier, R.E. Bolmaro, K.U. Kainer, J. Homeyer, Acta Mater. 54 (2006) 549–562. [7] S. Begum, D.L. Chen, S. Xu, A.A. Luo, Metall. Mater. Trans. A 39 (2008) 3014–3026. [8] D. Sarker, D.L. Chen, Scr. Mater. 67 (2012) 165–168. [9] S.B. Yi, S. Zaefferer, H.G. Brokmeier, Mater. Sci. Eng. A 424 (2006) 275–281. [10] P. Yang, Y. Yu, L. Chen, W. Mao, Scr. Mater. 50 (2004) 1163–1168. [11] C.L. Fan, D.L. Chen, A.A. Luo, Mater. Sci. Eng. A 519 (2009) 38–45. [12] J. Hirsch, T. Al-Samman, Acta Mater. 61 (2013) 818–843. [13] S. Begum, D.L. Chen, S. Xu, A.A. Luo, Int. J. Fatigue 31 (2009) 726–735. [14] S. Begum, D.L. Chen, S. Xu, A.A. Luo, Mater. Sci. Eng. A 517 (2009) 334–343. [15] X.Z. Lin, D.L. Chen, Mater. Sci. Eng. A 496 (2008) 106–113. [16] Q. Ma, H. El Kadiri, A.L. Oppedal, J.C. Baird, B. Li, M.F. Horstemeyer, S.C. Vogel, Int. J. Plasticity 29 (2012) 60–76. [17] J. Wang, L. Liu, C.N. Tomé, S.X. Mao, S.K. Gong, Mater. Res. Lett. 1 (2013) 81–88.
Contents lists available at SciVerse ScienceDirect
Materials Science & Engineering A journal homepage: www.elsevier.com/locate/msea
Rapid communication
Texture transformation in an extruded magnesium alloy under pressure D. Sarker, D.L. Chen n Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3
art ic l e i nf o Article history: Received 8 May 2013 Accepted 18 June 2013 Available online 26 June 2013 Keywords: Magnesium alloy Texture Twinning Orientation distribution function Compressive deformation
a b s t r a c t ̄ 0〉 ̄ and {0001} Extruded AM30 magnesium alloy showed two types of initial basal textures {0001}〈211 〈101̄0〉. Compressive deformation along extrusion direction resulted in their vanishing and the formation of {1̄21̄0}〈0001〉 and {011̄0}〈0001〉 textures, indicating that the c-axes always rotated towards the anticompression direction due to extension twinning. & 2013 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
As the lightest metallic structural material, magnesium alloys are promising for the application in the transportation industry to reduce vehicle weight and fuel consumption [1]. However, their widespread application is limited by the poor room temperature formability and strong anisotropy, which are mainly due to the development of crystallographic texture with basal planes of most grains aligned parallel to the rolling/extrusion direction. A tensile or compressive load along the c-axis of a hcp unit cell may cause the formation of extension or contraction twins, leading to the re-orientation of basal planes by ∼861 and ∼561, respectively, and contributing to the texture evolution [2,3]. The anisotropy in the mechanical properties results from a combination of initial texture and twin formation. For example, the forming behavior of magnesium alloys depends on the initial texture, processing condition and deformation temperature where slip and twinning played a vital role in the texture evolution [4,5]. The texture component in an AZ31 magnesium alloy also changed during tensile loading [6]. It is unclear what texture components are present and how they change in an extruded AM30 magnesium alloy during compression. The purpose of this study was, therefore, to identify the texture components and their evolution with increasing compressive strain in AM30 magnesium alloy.
Compression tests using computerized Instron machine at a strain rate of 1.25 10–4 s−1 were performed up to failure and several intermediate strains with cylindrical specimens (Φ5 mm 8 mm) where compression axis was parallel to ED. The deformed samples were cut along the compression axis, cold-mounted, and polished up to 1 μm diamond paste. Texture was determined using a PANalytical X-ray diffractometer by measuring incomplete pole figures between Ψ¼0–751 using Cu-Kα radiation at 45 kV and ̄ 40 mA. Five pole figures ({0001}, {101̄0}, {1011}, {112̄ 0}, {101̄3}) were used to calculate the orientation distribution function (ODF) using the MTEX software. Defocusing due to the rotation of sample holder was corrected using experimentally determined data from the diffraction of magnesium powders. Bunge notations of the Euler angles (φ1 Φ φ2) were used to represent the ODF.
n
Corresponding author. Tel.: +1 416 979 5000x6487; fax: +1 416 979 5265. E-mail address: [email protected] (D.L. Chen).
0921-5093/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msea.2013.06.048
3. Results and discussion The microstructure of the extruded AM30 alloy is shown in Fig. 1(a), consisting of a mix of large and small twin-free grains. The initial texture of this material, shown in Fig. 1(b), exhibited basically strong basal textures with a maximum intensity of 8.6 multiples of random distribution (MRD). The presence of strong concentration of (0001) poles with about 201 tilting towards the ED, along with (101̄0) poles towards both ED and TD, indicated that most of the grains with basal {0001} and prismatic {101̄0} planes were approximately parallel and perpendicular to the ED, respectively. Based on these results, a schematic diagram could be plotted in Fig. 1(c), where a specimen was
64
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
Extrusion direction
ED
TD
ND
ED
TD Fig. 1. (a) Microstructure, (b) (0001) and (101̄0) pole figures of the extruded AM30 magnesium alloy, (c) schematic diagram illustrating the relationship between the compression axis and c-axis of the crystals.
400
True stress, MPa
oriented with its cylindrical axis aligned parallel to the ED and the c-axis of the hcp unit cell was almost perpendicular to the ED. The true stress–true strain response of the sample is shown in Fig. 2, where the compressive yield strength was obtained to be 71 73 MPa, which was considerably lower than the tensile yield strength of ∼189 MPa [7]. The curve in Fig. 2 appeared peculiarly, relative to the normal tensile or compressive stress–strain curve of cubic metals. This was attributed to the occurrence of twinning in stage A and subsequent twin-dislocation interactions during compression [8]. The change of texture during compression is shown in Fig. 3 for several strain levels indicated by the vertical dashed lines in Fig. 2. At a strain of 1.5%, basal (0001) poles showed some extent of split of intensities from center towards radial direction (RD) with weak intensities along the ED, while prismatic (101̄0) poles with a moderate intensity were oriented towards ED, as shown in Fig. 3(a). More rotations of basal planes towards ED and prismatic planes towards the center were obvious with increasing strain level from 1.5% to 4.3% to 8.4% (Fig. 3(a)–(c)). The basal planes of further more
C
300
200 B 100
0
A A
0
3
6
9
12
15
18
True strain, % Fig. 2. A typical compressive true stress–true strain curve of AM30 magnesium alloy, where A, B and C indicate the strain hardening stages.
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
65
Fig. 3. (0001) and (101̄0) pole figures obtained from the compressed samples at a strain amount of (a) 1.5%, (b) 4.3%, (c) 8.4%, and (d) 12.9%.
grains were rotated to ED after 12.9% strain as indicated by the increasing maximum intensity from 12 to 16 MRD, while the prismatic planes were oriented in-between the center and RD, as shown in Fig. 3(d). To better understand the evolution of texture components, ODF was presented in a Euler space of 01≤φ1≤901,
01≤Φ≤901 and 01≤φ2≤601 as the alloy has hexagonal crystal symmetry. The texture change during compression at strain amounts of 0%, 4.3% and 12.9% is shown in Fig. 4(a), represented by the ODF sections at φ2 ¼01 and φ2 ¼301 from which the main texture components in hcp materials could be distinguished [6,9,10].
66
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
Strain=0%
Strain=4.3%
Schematic ODF
Strain=12.9%
1 1
A
C
D
B
1
D
25
A (90 20 0) B (90 20 30)
20
D {0110}<0001>
C (90 90 0)
f(g), M.R.D
D (90 90 30) 15
10
C { 1210}< 000 1>
5
A {0001}<2110> B {0001}<1010>
0 0
3
6
9
12
15
Strain, % Fig. 4. (a) ODF sections at φ2 ¼ 01 and φ2 ¼ 301, from the samples strained at 0%, 4.3% and 12.9%, and (b) the change of intensity of main texture components with the strain.
In the ODF sections several major components marked as A, B, C and D can be clearly identified, with the corresponding Euler angles given in Table 1. The undeformed alloy showed two types of basal ̄ 0〉 ̄ at orientation A(90, 20, 0) and texture components {0001}〈211 ̄ at orientation B(90, 20, 30), with their basal planes {0001}〈1010〉 being 7201 towards the ED as indicated by Φ¼201 while φ1 ¼901. A salient change in ODF at different strain levels was observed with respect to the undeformed alloy (Fig. 4(a)). That is, both texture ̄ 0〉 ̄ and B{0001}〈1010〉 ̄ disappeared, which components A{0001}〈211 ̄ were replaced by the formation of texture components C{1̄210} ̄ 〈0001〉 and D{0110}〈0001〉 at orientations (90, 90, 0), and (90, 90, 30), respectively, with increasing strain up to 12.9%. The change of components A to C in the ODF section of φ2 ¼01 and components B to D in the section of φ2 ¼301 with increasing strain indeed reflected a rotation of c-axes from an orientation of 7201 towards ED to that parallel to ED. This was equivalent to rotating the c-axes of most grains against the “push”. To quantify the change of these texture components, their intensity (f(g)) as a function of compressive strain was evaluated and plotted in Fig. 4(b). Clearly, components A and B rapidly faded away, while components C and D increasingly intensified. In the later stage of compressive deformation, the intensity of component D became higher than that of component C. This is likely related to the slightly higher density of component B
Table 1 Main texture components identified from Euler angles. Euler angles (φ1 Φ φ2)
(h k i l) [u v t w]
A (90, 20, 0) B (90, 20, 30) C (90, 90, 0) D (90, 90, 30)
̄ ̄0〉 7 201 towards ED {0001}〈211 ̄ 7 201 towards ED {0001}〈1010〉 {1̄21̄0}〈0001〉 {011̄0}〈0001〉
(8.8 MRD), as compared with that of component A (8.2 MRD), since component B subsequently changed to component D during compressive deformation. Similar results in an extruded AZ31 alloy were also reported in [6], where the intensity of component D was higher than that of component C. The observed change in the texture components can give us useful information about the deformation mode during compression. Based on the assumption that the intensifying of a texture component is at the expense of some other components, the development of components C and D can be associated with the weakening of components A and B. Such a rapid and large orientation change cannot be achieved by slip, but is possible by twinning [6,9,11,12]. The {101̄2} extension twinning has been
D. Sarker, D.L. Chen / Materials Science & Engineering A 582 (2013) 63–67
observed to play a predominant role in the texture evolution in the deformation of magnesium alloys [11,12], which was also responsible for the tension and compression anisotropy [13–15]. The initial components A and B with the c-axes of most grains nearly perpendicular to the ED (Figs. 1(b) and 4(a)) were favorably oriented for the activation of extension twinning when compressed along the ED (Fig. 1(c)). The occurrence of this type of twinning induces an 86.31 rotation of the basal plane or c-axis [2], so that the activation of {101̄2} twinning would satisfy the large orientation change of texture components A-C and B-D. The occurrence of abundant extension twinning in the extruded magnesium alloys, e.g., AM30, has been observed in [7,8,16]. Therefore, the evolution of texture components in the extruded magnesium alloy is predominantly related to the twinning. Additionally, as reported in [6,9,10], since the interplanar angle between components C and D is 301, the rotation of c-axes of most grains towards against the compression was anticipated to be also associated with the dislocation glide involving the twindislocation interactions and twin–twin interactions during deformation [8,16]. Further studies in this aspect are needed, e.g., by using atomic scale modeling and in-situ high-resolution transmission electron microscopy to observe the migration of twin boundaries during plastic deformation [17].
4. Conclusions The present study demonstrates that the compressive deformation along ED in AM30 extruded magnesium alloy led to a remarkable change in texture components. Both types of initial ̄ ̄0〉 and {0001}〈101̄0〉 were basal texture components {0001}〈211 observed to fade away, while {1̄21̄0}〈0001〉 and {011̄0}〈0001〉 texture components intensified with increasing compressive strain. Such texture changes revealed that the c-axes of hcp unit cells of most grains inside the material were always rotated towards against “push” or compression, mainly due to their 86.31 re-orientations stemming from extension twinning.
67
Prime novelty statement Two types of initial basal textures are identified in a recently developed AM30 extruded magnesium alloy. Both initial texture components disappear during compressive deformation, which are transformed into two new types of texture components, with the c-axes of hcp unit cells in most grains rotated towards the anticompression direction due to the re-orientations from extension twinning. Acknowledgments The authors would like to thank NSERC, PREA, NSERC-DAS Award, and AUTO21 for providing financial support. The authors also thank, Dr. A. Luo, Dr. R. Tandon and Dr. B. Davies for providing test materials, and Q. Li, A. Machin, J. Amankrah, and R. Churaman for assisting in the experiments. References [1] T.M. Pollock, Science 328 (2010) 986–987. [2] F.A. Mirza, D.L. Chen, D.J. Li, X.Q. Zeng, Mater. Sci. Eng. A 575 (2013) 65–73. [3] B.H. Lee, S.H. Park, S.G. Hong, K.T. Park, C.S. Lee, Mater. Sci. Eng. A 528 (2011) 1162–1172. [4] H.L. Kim, W.K. Bang, Y.W. Chang, Mater. Sci. Eng. A 552 (2012) 245–251. [5] Z. Zachariah, S.S.V. Tatiparti, S.K. Mishra, N. Ramakrishnan, U. Ramamurty, Mater. Sci. Eng. A 572 (2013) 8–18. [6] S.B. Yi, C.H.J. Davies, H.G. Brokmeier, R.E. Bolmaro, K.U. Kainer, J. Homeyer, Acta Mater. 54 (2006) 549–562. [7] S. Begum, D.L. Chen, S. Xu, A.A. Luo, Metall. Mater. Trans. A 39 (2008) 3014–3026. [8] D. Sarker, D.L. Chen, Scr. Mater. 67 (2012) 165–168. [9] S.B. Yi, S. Zaefferer, H.G. Brokmeier, Mater. Sci. Eng. A 424 (2006) 275–281. [10] P. Yang, Y. Yu, L. Chen, W. Mao, Scr. Mater. 50 (2004) 1163–1168. [11] C.L. Fan, D.L. Chen, A.A. Luo, Mater. Sci. Eng. A 519 (2009) 38–45. [12] J. Hirsch, T. Al-Samman, Acta Mater. 61 (2013) 818–843. [13] S. Begum, D.L. Chen, S. Xu, A.A. Luo, Int. J. Fatigue 31 (2009) 726–735. [14] S. Begum, D.L. Chen, S. Xu, A.A. Luo, Mater. Sci. Eng. A 517 (2009) 334–343. [15] X.Z. Lin, D.L. Chen, Mater. Sci. Eng. A 496 (2008) 106–113. [16] Q. Ma, H. El Kadiri, A.L. Oppedal, J.C. Baird, B. Li, M.F. Horstemeyer, S.C. Vogel, Int. J. Plasticity 29 (2012) 60–76. [17] J. Wang, L. Liu, C.N. Tomé, S.X. Mao, S.K. Gong, Mater. Res. Lett. 1 (2013) 81–88.