RT ECAP and rolling bestow high strength and good ductility on a low lithium aluminum alloy

Abstract

The pivotal role of lithium (Li) in improving the comprehensive mechanical properties of third-generation Al–Li alloys remains significant even at a low content. However, the strengthening contribution of a low dosage lithium and its combination with different processing methods remain largely unknown. This study aimed to investigate the strengthening effects of room-temperature (RT) equal channel angular pressing (ECAP) and rolling on Al–0.6Li alloy. Microstructural evolution during processing was monitored by optical microscope (OM), scanning electron microscope (SEM), electron backscattered diffraction (EBSD), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results revealed that simultaneous high ultimate tensile strength (UTS, 243 MPa) and yield strength (YS, 210 MPa) of the developed Al–0.6Li alloy were specifically achieved with a combination of RT ECAP and rolling, alongside an elongation (EL) of 9.5%. The gained strength improvement was primarily credited to the excellent fine-grain strengthening, as evidenced by a significant reduction in grain size from 101 μm to 1.47 μm, and dislocation strengthening, which, respectively, contributed to an increase of 91 MPa and 100 MPa in YS. Findings from this study demonstrate that with proper processing technology, the mechanical properties of Al–Li alloys with low Li content can be effectively improved, opening new avenues to develop high-performance Al–Li alloys.

Keywords

• Al–Li alloys
• ECAP
• Rolling
• Mechanical properties
• Microstructure