Additive Manufacturing of Highly Alloyed Aluminum–Lithium

Aluminum–lithium alloys offer significant potential for lightweight construction, exhibiting decreased density and improved specific stiffness as the lithium content increases. The specific stiffness of these alloys improves with lithium concentrations up to 14 at%, outperforming that of pure aluminum. However, traditional casting methods, constrained by low cooling rates, result in the precipitation of brittle AlLi phases at grain boundaries when the lithium content exceeds 9 at%, limiting further enhancements in stiffness. In this work, it presents laser-assisted additive manufacturing of binary Al–Li alloy powder with an increased lithium content of 14 at%. Unlike standard methods, this study utilizes an ultrashort pulse laser with a pulse duration of 250 fs at a wavelength of 1030 nm for the powder bed fusion process. With an average power of 150 W and a repetition rate of 32.5 MHz, it successfully demonstrates the production of highly dense Al-Li alloy specimens. Ex situ laser-induced breakdown spectroscopy is conducted to verify the high lithium content of the additively manufactured samples. Mechanical properties are assessed by measuring the elastic modulus and hardness. In addition, computer tomography, electron microscopy, and X-ray diffraction techniques are utilized for quantitative porosity analysis and to characterize microstructure and constituent phases.