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7475高强铝合金经过由固溶处理、轧制、再结晶组成的形变热处理工艺细化晶粒后,在适当条件下变形可呈现出良好的超塑性。在最佳变形条件下(T=510℃,ε_0=8.33×10~(-4)S~(-1)),获得最大延伸率为1700%。显微组织观察表明:Ⅲ区变形机制以晶间滑移为主,在晶内形成了位错亚结构。Ⅱ区的变形机制为晶界滑移伴随晶内位错运动。位错密度随应变的增加而增加。在Ⅰ区变形以扩散蠕度为主不包括晶间滑移。超塑变形Ⅱ区的激活能接近于体扩激散活能。基体中的体扩散是该合金超塑变形的速控过程
7475 high strength aluminum alloy after solution treatment, rolling, recrystallization consisting of deformation heat treatment process to refine the grain, the deformation under appropriate conditions can show a good superplasticity. Under the optimum deformation conditions (T = 510 ℃, ε_0 = 8.33 × 10 ~ (-4) S ~ (-1)), the maximum elongation was 1700%. Microstructure observation shows that the deformation mechanism of zone Ⅲ is dominated by intergranular slip, and dislocation substructures are formed in the grains. The deformation mechanism of zone Ⅱ is the grain boundary slip accompanied by dislocation movement in the grain. Dislocation density increases with strain. Deformation in zone I to spread the main creep does not include intergranular slip. Superplastic deformation zone Ⅱ activation can be close to the body to expand the scattered activation energy. The bulk diffusion in the matrix is the rate control process of the superplastic deformation of the alloy