Improved stress corrosion cracking resistance of in-situ TiB2/7050Al composite by pre-precipitation treatment

Gen Liu; Jiwei Geng; Yugang Li; Hongping Li; Mingliang Wang; Dong Chen; Naiheng Ma; Haowei Wang

doi:10.1016/j.micron.2021.103056

Improved stress corrosion cracking resistance of in-situ TiB₂/7050Al composite by pre-precipitation treatment

Micron. 2021 Jun:145:103056. doi: 10.1016/j.micron.2021.103056. Epub 2021 Mar 11.

Authors

Gen Liu¹, Jiwei Geng¹, Yugang Li², Hongping Li³, Mingliang Wang⁴, Dong Chen⁵, Naiheng Ma⁶, Haowei Wang¹

Affiliations

¹ State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China; School of Materials Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
² State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China.
³ Shanghai Aircraft Design and Research Institute, Shanghai, 201203, China.
⁴ State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China; School of Materials Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China. Electronic address: mingliang_wang@sjtu.edu.cn.
⁵ State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China; Anhui Provincial Engineering Research Center of Aluminum Matrix, Huaibei, 235000, China. Electronic address: chend@sjtu.edu.cn.
⁶ State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China; School of Materials Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China; Anhui Provincial Engineering Research Center of Aluminum Matrix, Huaibei, 235000, China.

PMID: 33740567
DOI: 10.1016/j.micron.2021.103056

Abstract

A two-step aging treatment (50 L P, a peak aging following 50 ℃ pre-precipitation) has been investigated for the in-situ TiB₂/7050Al composite. The 50 L P composite has the comparable mechanical properties to the composite at peak-aged (T6) state, and even better stress corrosion cracking resistance over the composite with the retrogression and re-aging (RRA) treatment. In detail, the different aging conditions lead to different precipitate morphologies and grain boundary microchemistries. According to the microstructure characteristics in the Al matrix, the 50 L P composite has considerably increased grain boundary precipitate interspace in comparison with the T6 composite, since the lower aging temperature should result in the reduced grain boundary precipitate number. Furthermore, the 50 L P composite has more Cu content in the grain boundary precipitate and reduced precipitate free zone width over the RRA composite, indicating the improved stress corrosion cracking resistance. For the reinforcement, the TiB₂ particles should slightly aggravate the stress corrosion cracking susceptibility, since the grain boundary precipitates are still the preferential corrosion sites due to their lower corrosion potentials.

Keywords: Al composite; Microstructures; Pre-precipitation; Stress corrosion cracking resistance; TiB(2).