以商业纯Mg和AA1050 Al板材为初始材料, 采用累积叠轧技术在室温下进行不同轧制道次变形制备了Mg/Al多层复合板材料, 并对3 cyc轧制的Mg/Al多层复合板材料在200 ℃分别进行不同时间退火处理. 利用OM, SEM和中子衍射技术对微观组织和宏观织构进行了研究. 结果表明, 复合板材中Mg和Al层组织均随着循环次数的提高而细化; 在200 ℃时随着退火时间的增加, 晶粒逐渐均匀但没有明显长大. 累积叠轧过程中Mg层主要呈现出典型的轧制织构类型, Al层则表现出以轧制织构组分为主, 同时伴有剪切织构组分的混合织构类型. 对于3 cyc轧制的Mg/Al多层复合板材, 在200 ℃经不同时间退火后, Mg层依然为轧制织构类型, Al层为轧制织构与剪切织构组分混合. 随着累积叠轧循环道次的增加, 屈服强度和抗拉强度都逐渐上升.
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.
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