Study on micro-structure, solid solubility and tensile properties of 5A90 Al–Li alloy cast by low-frequency electromagnetic casting processing

In this paper, the low-frequency electromagnetic casting (LFEC) processing was introduced as an efficient pollution-free casting technique, and how it influenced the micro-structure and mechanical properties of 5A90 Al–Li alloy was investigated. The mechanical properties of the alloy had a close connection with the casting metallurgical quality and the precipitation phases. Compared to the conventional direct chill casting (DCC), the LFEC could promote the precipitate of the δ′ (Al3Li)/β′ (Al3Zr) and reduce the width of PFZ, which enhanced the effect of the precipitation strengthen and alleviated the strain localization. Meanwhile, the micro-structure of the ingot was refined significantly and the metallurgical quality was improved after LFEC treatment due to the modification of the flow and temperature field of the sump that caused by the application of low-frequency electromagnetic field. Maximum yield strength and ultimate tensile strength of as-aged alloy cast by LFEC with 150 A/15 Hz could reach 371.85 MPa and 495.5 MPa, while elongation remained at 9.82%.