钪含量对7055铝合金微观组织及性能的影响

Effect of Sc content on microstructure and properties of 7055 aluminum alloy

在7055铝合金中添加不同含量的Sc,研究钪含量对不同状态的7055铝合金微观组织、力学性能、耐腐蚀性能的影响规律.研究结果表明:添加Sc后7055铝合金晶粒得到明显细化,树枝晶转变为等轴晶,添加质量分数分别为0.15%、0.25%的Sc,晶粒分别由125μm细化到约90μm和45μm.添加w(Sc)=0.35%和w(Sc)=0.45%的铸态7055铝合金晶粒尺寸差别不大.Sc在7055铝合金中生成的Al3(Sc,Zr)相可以抑制再结晶和晶粒长大,提高再结晶温度,使含Sc的7055铝合金在固溶、时效之后仍保留大量的变形组织.由于细晶强化、亚结构强化以及第二相强化效应,含Sc的7055铝合金表现出更高的强度及硬度.添加质量分数分别为0.15%和0.25%的Sc后,7055铝合金的屈服强度都从601 N/mm^2提高到636N/mm^2;抗拉强度分别从630N/mm^2提高到670 N/mm^2和672 N/mm^2;伸长率下降.添加w(Sc)为0.35%和0.45%的Sc后,屈服强度和抗拉强度相比w(Sc)为0.15%和0.25%的有所下降,伸长率提高.添加w(Sc)为0.25%和0.45%的Sc后,剥落腐蚀等级都由ED级提高到了EA级;晶间腐蚀深度由304.7μm分别变浅为219.0μm和261.4μm,耐腐蚀性能提高.

Different contents of scandium were added to 7055 aluminum alloy.The effects of Scandium content on the microstructure,mechanical properties and corrosion resistance of 7055 aluminum alloy of different tempers were studied.The study results show that the grain size of 7055 aluminum alloy is refined obviously after adding Sc element,and dendrite is transformed into equiaxed grain.After adding w(Sc)=0.15% and w(Sc)=0.25%scandium,the grain size of 7055 aluminum alloy is refined from 125μm to about 90μm and 45μm,respectively.The grain sizes of as-cast 7055 aluminum alloy with w(Sc)=0.35% and w(S c)=0.45%scandium are not obviously different.Al3(Sc,Zr)phase formed by scandium in 7055 aluminum alloy can inhibit recrystallization and grain growth.Increase recrystallization temperature,and make 7055 aluminum alloy containing scandium retain a large amount of deformed structure after solution aging.Due to fine grain strengthening,substructure strengthening and second phase strengthening,7055 aluminum alloy containing scandium exhibit higher strength and hardness.After adding w(Sc)=0.15% and w(Sc)=0.25% scandium,yield strength increases from 601 N/mm^2 to 636 N/mm^2,tensile strength increases from 630 N/mm^2 to 670 N/mm^2 and 672 N/mm^2,respectively,and elongation decreases.When scandium content increases to w(Sc)=0.35% and w(Sc)=0.45%,yield strength and tensile strength decrease compared with that of 0.15% and 0.25%,and elongation increases.After adding w(Sc)=0.25% and w(Sc)=0.45% scandium,the exfoliation corrosion grade is increased from ED to EA,and the intergranular corrosion depth is reduced from 304.7μm to 219.0μm and 261.4μm,respectively.The corrosion resistance is improved.