Earlier dynamical tensile loading measurements, performed with the help of a Hopkinson bar assembly line, on diffusion-welded joints of 2017 aluminium-copper alloys, have been completed. The welding temperature was changed from 500 degrees C to 575 degrees C, the welding time was fixed at either 30 min or 2 h, and the welding pressure at either 2 or 5 MPa. Measurements of the mechanical properties were also performed on treated specimens which were base-material specimens subjected to the same thermal cycle as the welded samples. These results, obtained up to 600 degrees C, have been used as a reference for a direct comparison with the welded sample strengths. The more precise measurements reported here agree well with the earlier results. However, they reveal, at high temperatures (above 575 degrees C), a large decrease in the tensile strength of the treated specimens, which was not observed previously. Moreover, they allow the effects of the welding pressure and time on the welded joint strength to be distinguished more precisely. In order to gain a better understanding of the relationship between the welded joints dynamical properties and their microstructures, the failure surfaces were observed by scanning electron microscopy. In addition, some energy-dispersive X-ray spectra were also recorded in order to reveal the chemical nature of the failure surfaces. At low temperatures, the failure surface of the welded specimens was smooth and precipitate-free. On the contrary, at high temperatures, the failure surface was characteristic of a ductile failure mode and exhibited two kinds of precipitates, one rounded and the other oblong, at the origin of dimple formation.