Existing form and harmful effects of sodium in Al-4.5%Cu alloy
(Key Laboratory for Liquid-Solid Structure Evolution and Processing of Materials, Ministry of Education,
Shandong University, Ji’nan 250061, China)
Shandong University, Ji’nan 250061, China)
Abstract: Plentiful sodium was introduced into the alloy using salt fluxes as medium, then the existing form and influence of sodium on the microstructure and tensile properties of Al-4.5%Cu (mass fraction) alloy were investigated. It is proved that the elemental sodium segregates at the grain boundaries of Al-4.5%Cu alloy and weakens the bond between the matrix and CuAl2-phase. After T6 heat treatment, sodium results in micro-fracture and induces the residual of CuAl2-phase in Al-4.5%Cu alloy.The tensile test results show that the sodium causes a transition from dimple fracture to intergranular fracture, which makes the mechanical performance of Al-4.5%Cu decrease dramatically.
Key words: Al-Cu alloy; sodium; grain boundaries; fracture; mechanical performance