高Li含量Al-Cu-Li合金时效析出相的分布与演化（英文）

采用透射电镜研究高Li含量(2.14%,质量分数)1460铝锂合金T6(145、160、175℃)及T8双级时效(4%预变形,130℃,24 h+160℃)时析出相的演化及分布。合金的时效析出相包括δ'(Al_3Li)相和T1(Al_2CuL i)相,其中δ'相为晶内优先析出相。低温(145℃)T6时效时,晶内还形成大量均匀分布而且稳定的δ'/GPI/δ'复合相。较高温度(160℃及175℃) T6时效时,还会析出大量T1相;T1相优先于(亚)晶界形核,而后随时效时间延长,逐渐在晶内析出。T8双级时效时,晶内可形成δ'/GPI/δ'复合相及T1相;其中δ'/GPI/δ'复合相开始形成于第一级低温时效,并于第二级较高温度时效时一直稳定存在;T1相则形成于第二级时效,且T8时效时的预变形促进T1相在晶内快速析出。

Distribution and evolution of aging precipitates in Al-Cu-Li alloy with high Li concentration

The evolution and distribution of the aging precipitates in 1460 Al-Li alloy with high Li concentration (2.14%, mass fraction) during T6 aging and two-step T8 (4% predeformation) aging were investigated through TEM. The aging precipitates include δ'(Al3Li) and T1 (Al2CuLi) phases, of which the δ' phases are formed first in grain interiors. A lot of δ'/GPI/δ' composite precipitates in which GPI zones are flanked with a pair of δ' phases, are formed at 145℃ of T6 aging, which are thermally stable. At 160℃ and 175℃ of T6 aging, many T1 phases nucleate first at subgrain boundaries and grain boundaries, and then form and grow within grains. As to the T8 aging, the δ'/GPI/δ' composite precipitates are formed during the first-step aging at 130℃ for 20 h, which are thermally stable during the second-step aging at 160℃. The plastic predeformation accelerates T1 nucleation within grains during the second-step aging at 160℃.