AlLi alloys, as promising ultra-light airframe structural materials, have attracted extensive attention with respect to improving their mechanical properties. However, due to the detrimental effect of Li, the strength and ductility of Al-Mg-Li alloys have been found to be relatively low. In this work, high strength and simultaneously improved ductility were achieved in an Al-Mg-Li alloy with a high Li content by accurately controlling the microstructure through equal channel angular pressing (ECAP) and post-heat treatment. During the ECAP procedure, ultrafine grains with precipitating S₁ phases were obtained in the alloy. Then, relatively coarse S₁ phases due to the high Li content were effectively refined, large amounts of fine metastable δ’ phase particles uniformly precipitated without precipitate-free zones (PFZs), and ultrafine grains remained during subsequent heat treatment, thus achieving a combination of high strength (>450 MPa) and good ductility (>13.5%). The heat treatment including short-term solution and ageing after severe plastic deformation (SPD) was verified to be applicable to other AlLi alloys to adjust the ultrafine microstructure and achieve an optimal combination of strength and ductility, which can increase the applications of AlLi alloys for lightweight key components in the aerospace field

铝锂合金作为有前途的超轻机身结构材料，在改善其机械性能方面引起了广泛的关注。然而，由于Li的有害作用，已经发现Al-Mg-Li合金的强度和延展性相对较低。在这项工作中，通过等通道角挤压（ECAP）和后热处理来精确控制微观结构，从而在具有高Li含量的Al-Mg-Li合金中实现了高强度并同时提高了延展性。在ECAP过程中，在合金中获得了具有S ₁相沉淀的超细晶粒。然后，相对粗糙的S ₁有效地精炼由于高Li含量引起的相，大量均匀的亚稳δ'相细小颗粒均匀沉淀而没有无沉淀区（PFZs），并且在随后的热处理过程中保留了超细晶粒，从而实现了高强度（> 450）的结合MPa）和良好的延展性（> 13.5％）。经验证，包括短期固溶和严重塑性变形后的时效（SPD）在内的热处理可用于其他Al Li合金，以调节超细微结构并实现强度和延展性的最佳组合，从而可以增加Al Li的应用航空领域轻质关键部件用合金