钠在Al-4.5Cu合金中的存在形式及不利影响

摘要

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.%通过熔盐向Al−4.5%Cu引入足量的钠，研究钠在Al−Cu合金中的存在形式以及对合金显微组织和抗拉性能的影响。结果表明：钠以单质形式存在于合金晶界中，这种钠降低了基体和CuAl2相之间的结合力。T6时效处理后，钠导致了微观裂纹的产生和CuAl2相的残留。抗拉实验的结果显示钠使得合金的断裂方式由韧窝断裂向晶间断裂转变，这导致了合金性能的急剧降低。