Influence of temperature on creep behavior, mechanical properties and microstructural evolution of an Al-Cu-Li alloy during creep age forming

• Published in: Journal of Central South University Vol. 28; no. 8; pp. 2285 - 2294
• Main Authors: Zhou, Chang, Zhan, Li-hua, Li, He, Zhao, Xing, Huang, Ming-hui
• Format: Journal Article
• Language: English
• Published: Changsha Central South University 01.08.2021; Springer Nature B.V
• Subjects: Aging; Aging (metallurgy); Aluminum base alloys; Copper; Creep rate; Diffusion; Dislocations; Engineering; Evolution; Heat treating; Mechanical properties; Metallic Materials; Precipitates; Temperature effects; Tensile tests; 析出行为; precipitation; 力学性能; microstructure; Al-Cu-Li 合金; 微观组织; Al-Cu-Li alloys; creep age forming; 蠕变时效成形; mechanical properties
• ISSN: 2095-2899; 2227-5223
• DOI: 10.1007/s11771-021-4769-8

The effect of temperature in range of 155–175 °C on the creep behavior, microstructural evolution, and precipitation of an Al-Cu-Li alloy was experimentally investigated during creep ageing deformation under 180 MPa for 20 h. Increasing temperature resulted in a noteworthy change in creep ageing behaviour, including a variation in creep curves, an improvement in creep rate during early creep ageing, and an increased creep strain. Tensile tests indicate that the specimen aged at higher temperature reached peak strength within a shorter time. Transmission electron microscopy (TEM) was employed to explore the effect of temperature on the microstructural evolution of the AA2198 during creep ageing deformation. Many larger dislocations and even tangled dislocation structures were observed in the sample aged at higher temperature. The number of T 1 precipitates increased at higher ageing temperature at the same ageing time. Based on the analysed results, a new mechanism, considering the combined effects of the formation of larger dislocation structures induced by higher temperature and diffusion of solute atoms towards these larger or tangled dislocations, was proposed to explain the effect of temperature on microstructural evolution and creep behaviour.