Li对Al-3.5Cu-1.5Mg合金力学性能与时效析出行为的影响

摘要

采用拉伸实验、扫描电子显微分析(SEM)、透射电子显微分析(TEM)、高分辨电子显微技术研究Li添加对Al-3.5Cu-1.5Mg合金力学性能与时效析出行为的影响。结果表明：添加1.0%Li能使Al-3.5Cu-1.5Mg合金的峰值时效拉伸强度明显提高，伸长率略有下降。峰值时效拉伸样品的断口形貌由韧断口转变为韧/脆混合型。Li使合金185°C 峰值时效时间由12 h 延长至24 h，析出相由 S '(Al2CuMg)转变为 S '(Al2CuMg)+δ'(Al3Li)。在Al-3.5Cu-1.5Mg-1.0Li合金中，S'(Al2CuMg)相时效析出延缓。%The influence of Li addition on mechanical property and aging precipitation behavior of Al-3.5Cu-1.5Mg alloy was investigated by tensile test, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results show that the tensile strength can be significantly improved with the slightly decreased ductility and the form of fracture morphology is converted from ductile fracture into ductile/brittle mixed fracture by adding 1.0%Li. Besides, the peak aging time at 185 °C is delayed from 12 to 24 h and the main precipitation phase S'(Al2CuMg) is converted into S' (Al2CuMg)+δ'(Al3Li), while the formation of S'(Al2CuMg) is delayed.