Effect of Mn alloying on the microstructure and compression performances of in-situ bonding Al–4Cu–1Ca foam-filled tubes

For melt foaming prepared Al–Cu foam, in which Calcium (Ca) was used as a thickening agent, the formation of strengthening phases (θ-Al 2 Cu) was prevented, and T phases (Al–Cu–Ca intermetallics) were formed. In this work, the microstructural evolution and compression performance of the in-situ bonding Al–4Cu–1Ca foam-filled tubes (FFT) with various Manganese (Mn) contents were studied. Through microstructure characterization and compression performance test, the refinement of grains, the evolution of the grid-like eutectic and precipitated phases, and the compression properties of Al–4Cu–1Ca FFTs due to Mn alloying were discussed. The strengthening and plasticity-improving mechanism of Mn alloying was revealed. The results show that Al 6 Mn phases were formed in the as-foamed Al–4Cu–1Ca alloys with the Mn addition. The Al 6 Mn phases serve as the precipitation sites for the T phases, resulting in the refinement of the T phases. For the Al–4Cu–1Ca–1.0Mn FFT, the energy absorption and specific energy absorption reached 15.59 MJ/m 3 and 23.05 kJ/kg, respectively. This study aims to develop an efficient strategy for achieving in-situ bonding of Al–4Cu–1Ca FFTs with superior energy absorption performance, while simultaneously overcoming the strength–plasticity trade-off.