少量Sc对7055铝合金组织与性能的影响

Effect of minor addition of scandium on microstructures and mechanical properties of 7055 aluminum alloy

利用拉伸试验、光学金相、X射线物相分析、SEM及TEM等实验方法,研究了添加0.2%Sc(质量分数)对7055铝合金组织与性能的影响.实验结果表明,添加0.2%Sc可以显著细化7055铝合金铸态晶粒并减少晶界非平衡共晶相数量,促进非平衡共晶相在均匀化退火时的溶解,从而提高合金固溶度;由于Sc的添加可以提高7055Sc合金的溶质原子固溶度、形成更为均匀弥散分布的A l3ScZr粒子、以及抑制变形组织再结晶和有效细化固溶处理后的(亚)晶粒尺寸,因而显著提高7055Sc合金综合力学性能.

The effects of small amount of scandium （0. 2%, weight fraction） on the microstructures and properties of 7055 aluminum alloy were investigated using tensile test, optical observation, X - ray diffraction analyses, scanning electron microscopy and transmission electron microscopy. The results showed that due to the addition of 0. 2% Sc, cast grain size of 7055Sc alloy was greatly refined and non- equilibrium constituent phases were reduced. The improvement of mechanical properties of 7055Sc alloy was contributed to the higher solid solubility of Zn, Mg and Cu atoms, the dispersion of Al3 ScZr particles and the （ sub - ） grain boundary strengthening.