Thin film metallic glasses (TFMGs) are known for their combination of mechanical properties such as large yield strength and ductility, limiting the brittle failure typical of the bulk counterparts 1. Recently, it has been discovered that pulsed laser deposition (PLD) enables to synthetize a novel class of ZrCu TFMGs with tunable nanoscale morphology, with the formation of compact and nanogranular TFMGs by simply adapting the background gas pressure during the deposition. This leads to a tunable mechanical behavior with yield strength up to ~3 GPa and ductility >9% 2. Nevertheless, the effect of composition on the mechanical properties is largely unknown and need to be further explored, especially with the addition of a third element to the base ZrCu alloy. Here, we investigate the addition of Al to Zr50Cu50 base (ZrCuAlx) with different content ranging from 0 up to 13 (% at.), while tuning the morphology by depositing compact and nanogranular films. In parallel, a second series of samples was grown by magnetron co-sputtering of pure metallic targets for comparison purposes. The atomic structure and chemical composition have been investigated by X-ray diffraction/reflectivity (XRD/XRR) and scanning electron microscopy equipped with energy dispersive spectroscopy (SEM/EDX). The mechanical properties have been measured by optoacoustic techniques, nanoindentation and tensile test on Kapton® substrate. We show that ZrCuAlx TFMGs deposited by PLD in vacuum (<2x10-3 Pa) are compact, while the ones deposited in 5 Pa He have a nanogranular structure as a result of the cluster-assembled growth. Both compact and nanogranular TFMGs are 10% denser than bulk counterparts, while possessing a self-assembled nanolayered structure. Moreover, we show that the mechanical properties, including shear (G) and Young’s (E) moduli and hardness (H) increase with Al content from respectively 44, 120 and 8.8 GPa for Zr50Cu50 up to 49, 133 and 9.3 GPa for Zr46Cu46Al8 due to the enhanced formation of strong Zr-Al bonds. Furthermore, we show that films with different morphologies have the same elastic behavior as a result of a similar local chemistry. However, we show that ZrCuAlx by PLD have ~30% higher G, E and H than magnetron sputtered ones with the same composition due to the higher energies involved in the laser ablation process, favoring a more compact and denser atomic structure. Finally, tensile tests on flexible Kapton® substrates have shown a larger onset of crack formation for compact ZrCuAlx TFMGs (~1.3%) with respect to nanogranular ZrCuAlx (~1.04%). Overall, we show that PLD enables to synthetize a novel class of ZrCu and ZrCuAl TFMGs with tunable microstructure and composition, leading to different mechanical properties with potential interest for a variety of applications. References 1. D. Tönnies et al., Advanced Materials 26 (32), 5715-5721 (2014). 2. M. Ghidelli et al., Acta Materialia 213, 9 (2021).