Aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactory producing aluminium joints, in a faster and reliable manner. In the present work dissimilar Al alloys (AA2024-T351 and AA6056-T4) were friction stir welded. Butt joints were obtained by varying process parameters, namely the rotational speed (500-1200 rpm) and the welding speed (150-400 mm/min.), while axial force and tool geometry were kept constant. Parameter optimisation, which has been based on the results of

No abstract

This letter proposes a criterion to quantitatively correlate chemical composition with crystallization behaviors of Al-based glass-former alloys. By extending to multicomponent systems the topological instability model of Egami and Waseda [J. Non-Cryst. Solids 64, 113 (1984)], we introduce a “lambda (λ) criterion” according to which amorphous alloys with λ>0.1 exhibit glassy behavior, whereas alloys with λ<0.1 are nanocrystalline. Nanoglassy alloys occur when λ≈0.1. A large number of experimental findings in the literature supports the λ criterion, rendering it a useful tool for the design and selection of glass-former systems and compositions.

No abstract

No abstract