微观组织与性能的影响
(1. 西南铝业(集团)有限责任公司技术中心, 重庆 401326)
(2. 中南大学 材料科学与工程学院， 长沙 410083)
摘 要: 通过合金室温力学性能测试及时效组织的透射电镜分析，研究了分级时效对Al-Cu-Li-Mg-Mn-Zr合金显微组织与性能的影响。结果表明， 经过先低温后高温的三级时效可使合金获得比T6处理更高的强度, 且随着第二级时效时间的延长， 合金抗拉强度和屈服强度逐渐提高。采用先高温后低温二级时效，可获得较先低温后高温三级时效更高的力学性能， 且其强度随第一级高温时效时间的延长而增加， 达到T8峰时效的强度水平。合金在先低温后高温时效时，在100 ℃低温预时效形成GP区， 在140 ℃析出弥散细小的δ′、θ′和T1相并稳定下来， 然后在175 ℃进一步析出长大， 从而提高了合金强度。当合金在先高温后低温二次时效时，高温欠时效析出δ′和T1等强化相，然后在140 ℃较低温度二次析出大量细小弥散的δ′相，产生二次强化效果。
关键字: 铝锂合金; 时效; 微观结构；力学性能
Al-Cu-Li-Mg-Mn-Zr alloys
（ 1. Technology Centre, Southwest Aluminum Industry Ltd.Co.,
Chongqing 401326, China;
(2. School of Materials Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: The effects of multi-stage ageing treatments on the microstructure and mechanical properties of Al-Cu-Li-Mg-Mn-Zr alloy were investigated．Compared with T6 treatment, higher mechanical properties can be obtained by multi-stage ageing treatments， especially the treatment of (175 ℃, 24 h)+(140 ℃, 36 h) leads to an excellent combination of strength and ductility. When the alloy is pre-aged at lower temperature(100 ℃), the GP zone is preferentially precipitated, and the fine and dispersed δ′, θ′ and T1 phases are precipitated at 140 ℃. These precipitates continue to grow at 175 ℃, which improves the strength of alloy. The combined effects of δ′, θ′ and T1 precipitates at the first age stage of 175 ℃ and the secondary-precipitation at the second stage of 140 ℃ can be aroused, which results in higher strength(close to that in T8 treatment) than that of the alloy pre-aged at lower temperature then at elevated temperature.
Key words: Al-Li alloy; ageing; microstructure; mechanical property
