中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 31 No. 5 May 2021 |
（1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
3. State Key Laboratory of High-Performance Complex Manufacturing, Central South University, Changsha 410083, China;
4. Beijing Institute of Astronautic Systems Engineering, Beijing 100076, China）
Abstract:A unified constitutive model is presented to predict the recently observed “multi-stage” creep behavior of Al-Li-S4 alloy. The corresponding microstructural variables related to the yield strength and creep deformation of the alloy during the creep ageing process, including dislocations and multiple precipitates, have been characterized in detail by X-ray diffraction (XRD) and transmission electron microscopy (TEM). For the yield strength, the model considers the multiphase strengthening behavior of the alloy based on strengthening mechanisms, which includes shearable T1 precipitate strengthening, non-shearable T1 precipitate strengthening and θ′ precipitate strengthening. Based on creep deformation mechanism, the “multi-stage” creep behavior of the alloy is predicted by introducing the effects of interacting microstructural variables, including the radius of multiple precipitates, dislocation density and solute concentration, into the creep stress-strain model. It is concluded that the results calculated by the model are in a good agreement with the experimental data, which validates the proposed model.
Key words: constitutive modelling; Al-Li-S4 alloy; creep age forming; microstructures; numerical algorithms
