Liu Jinqiu, Guo Fuqiang, Matsuda Kenji, Wang Tao, Zou Yong
Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, School of Materials Science and Engineering, Shandong University, Jinan 250061, China.
Faculty of Sustainable Design, University of Toyama, Toyama 930-8555, Japan.
Materials (Basel). 2023 Mar 2;16(5):2054. doi: 10.3390/ma16052054.
In this paper, the effects of compressive pre-deformation and successive pre-artificial aging on the compressive creep aging behavior and microstructure evolution of the Al-Cu-Li alloy have been studied. Severe hot deformation mainly occurs near the grain boundaries during the compressive creep initially, which steadily extends to the grain interior. After that, the T phases will obtain a low radius-thickness ratio. The secondary T phases in pre-deformed samples usually only nucleate on dislocation loops or Shockley incomplete dislocations induced by movable dislocations during creep, which are especially prevalent in low plastic pre-deformation. For all pre-deformed and pre-aged samples, two precipitation situations exist. When pre-deformation is low (3% and 6%), solute atoms (Cu and Li) can be consumed prematurely during pre-aging at 200 °C, with dispersed coherent Li-rich clusters in the matrix. Then, the pre-aged samples with low pre-deformation no longer have the ability to form secondary T phases in large quantities during subsequent creep. When dislocation entangles seriously to some extent, a large quantity of stacking faults, together with a "Suzuki atmosphere" containing Cu and Li, can provide the nucleation sites for the secondary T phase, even when pre-aged at 200 °C. The sample, pre-deformed by 9% and pre-aged at 200 °C, displays excellent dimensional stability during compressive creep because of the mutual reinforcement of entangled dislocations and pre-formed secondary T phases. In order to decrease the total creep strain, increasing the pre-deformation level is more effective than pre-aging.
本文研究了压缩预变形和连续预时效对Al-Cu-Li合金压缩蠕变时效行为及微观组织演变的影响。在压缩蠕变初期，严重的热变形主要发生在晶界附近，随后逐渐向晶粒内部扩展。此后，T相将获得较低的半径-厚度比。预变形样品中的二次T相通常仅在蠕变过程中由可动位错诱导产生的位错环或肖克莱不全位错上形核，这在低塑性预变形中尤为普遍。对于所有预变形和预时效样品，存在两种析出情况。当预变形量较低（3%和6%）时，溶质原子（Cu和Li）在200℃预时效过程中会过早消耗，基体中存在弥散的相干富锂团簇。然后，预变形量低的预时效样品在随后的蠕变过程中不再有大量形成二次T相的能力。当位错在一定程度上严重缠结时，大量的层错以及含Cu和Li的“铃木气氛”可以为二次T相提供形核位点，即使在200℃预时效时也是如此。预变形9%并在200℃预时效的样品在压缩蠕变过程中表现出优异的尺寸稳定性，这是由于缠结位错和预先形成的二次T相的相互强化作用。为了降低总蠕变应变，增加预变形量比预时效更有效。
