1 Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413, China 2 School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Cite this article:
Meijuan LI,Xiaolong LIU,Yuntao LIU,Mingyi ZHENG,Chen WANG,Dongfeng CHEN. TEXTURE EVOLUTION AND MECHANICAL PROPER-TIES OF Mg/Al MULTILAYERED COMPOSITE SHEETSPROCESSED BY ACCUMULATIVE ROLL BONDING. Acta Metall Sin, 2016, 52(4): 463-472.
Mg and its alloys are regarded as potential candidates to replace steel and other heavier materials in some applications due to low density and high specific strength. However, the application of Mg alloys is limited because of their low strength, poor formability and corrosion resistance. Grain refinement and Mg-Al composite have been applied successfully to improve the strength and formability of Mg alloys. The accumulative roll bonding (ARB) is one kind of severe plastic deformation process which can produce bulk ultra-fine grained metallic materials. In the present work, the ultra-fine grained alternative Mg/Al multilayered composite sheets were fabricated at room temperature by ARB process using commercial pure Mg and AA1050 Al sheets up to 3 cyc. Some of Mg/Al sheets after 3 cyc ARB were annealed at 200 ℃ for 15, 60 and 90 min, respectively. The microstructure of ARBed sheets were invesgated by OM and SEM. The global texture evolution of these ARBed sheets were measured by neutron diffraction. It is found that the grains in both Mg and Al layers are refined gradually with the increase of ARB cycles. Although the grains in the Mg layers didn't grow up obviously after annealing at 200 ℃ for different times, the homogeneity of the microstructure was improved. The Mg layers of ARBed sheets showed typical rolling texture which enhanced with the increase cycle of ARB process up to 2 cyc and decreased sligthly after 3 cyc. The Al layers exhibited a combination texture types of rolling and shear texture, including Copper, S, Brass and rotated cube (RC) texture components. After 200 ℃ annealing, the Mg layers remained typical rolling texture component and it's intensity enhanced significantly after 15 min annealing and kept stable during the following annealing processing. The Al layers maintained a combination of rolling and shear texture components, the intensity of rolling components became stronger after 15 min annealing, then decreased after 60 and 90 min annealing. The yield strength and tensile strength were improved while the ARB cycle increased.
Fig.1 SEM images of Mg/Al multilayered composite sheet after primary preparation without accumulative rolling bonding (ARB) (a) and after 1 cyc (b), 2 cyc (c) and 3 cyc (d) of ARB
Fig.2 OM images of Mg layer in Mg/Al multilayered composite sheet after primary preparation (a, b) and ARBed for 1 cyc (c, d) , 2 cyc (e, f) and 3 cyc (g, h) at low (a, c, e, g) and high (b, d, f, h) magnifications
Fig.3 OM images of Mg layer in Mg/Al multilayered composite sheet after 3 cyc ARB and annealing at 200 ℃ for 15 min (a, b), 60 min (c, d) and 90 min (e, f) at low (a, c, e) and high (b, d, f) magnifications
Fig.4 (0002) pole figures of Mg layer in Mg/Al composite sheet after primary preparation (a) and ARBed for 1 cyc (b), 2 cyc (c) and 3 cyc (d) (RD—rolling direction, TD—transverse direction)
Fig.5 Orientation distribution function (ODF) figures of Al layer in Mg/Al composite sheet after primary preparation (a, a1, a2), ARBed for 1 cyc (b, b1, b2), 2 cyc (c, c1, c2) and 3 cyc (d, d1, d2) at Euler angles of 45° (a~d), 65° (a1~d1) and 90° (a2~d2) (RC—rotated cube)
Fig.6 Intensities of orientation lines α (a), β (b) and τ (c) of Al layer in ARBed Mg/Al multilayered composite sheet after different cycles (f(g)—orientation density, φ1, φ2, ?—Euler angles)
Cycle
Yield strength
Tensile strength
cyc
MPa
MPa
0
140
183
1
160
199
2
169
211
3
174
220
Table 1 Mechanical properties of ARBed Mg/Al multilayered composite sheet after different cycles at room temperature
Fig.7 (0002) pole figures of Mg layer in 3 cyc ARBed Mg/Al multilayered composite sheet (a) and after annealing at 200 ℃ for 15 min (b), 60 min (c) and 90 min (d)
Fig.8 ODF figures of Al layer in 3 cyc ARBed Mg/Al multilayered composite sheet (a, a1, a2) and after annealing at 200 ℃ for 15 min (b, b1, b2), 60 min (c, c1, c2) and 90 min (d, d1, d2) at Euler angles of 45° (a~d), 65° (a1~d1) and 90° (a2~d2)
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