Microstructures and mechanical properties of Al-Li 2198-T8 alloys processed by two different severe plastic deformation methods: A comparative study

Authors

Zhixiong Zhu, University of WollongongFollow
Jian Han, University of WollongongFollow
Chong Gao, Beihang University
Mao Liu, University of TokyoFollow
Jianwei Song, Beihang University
Zhiwei Wang, Beihang University
Hui Jun Li, University of WollongongFollow

RIS ID

111436

Publication Details

Zhu, Z., Han, J., Gao, C., Liu, M., Song, J., Wang, Z. & Li, H. (2017). Microstructures and mechanical properties of Al-Li 2198-T8 alloys processed by two different severe plastic deformation methods: A comparative study. Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing, 681 65-73.

Abstract

In this study, the microstructural evolution and mechanical properties of Al-Li 2198-T8 (artificially peak aged) separately processed by two typical severe plastic deformation (SPD) methods (i.e. friction stir processing (FSP) and high-pressure torsion (HPT)) were investigated. The microstructural examination showed that both FSP and HPT were capable of refining the grains for Al-Li 2198-T8, and the HPT processing produced much finer grains. Transmission electron microscopic observation revealed that precipitates of β′ (Al₃Zr), θ′ (Al₂Cu) and T1 (Al₂CuLi) existing in the as-received Al-Li 2198-T8 fully dissolved after HPT, whereas the precipitates of β′ (Al₃Zr) were retained in the processed zone after FSP. The hardness and tensile testing demonstrated that the hardness and strength of FSP-processed alloy significantly declined compared to the as-received alloy, while those of HPT-processed alloy substantially increased due to exceptional grain refinement and high dislocation density. The strengthening mechanisms of the alloy before and after the SPD processing were discussed in the present paper.