Effect of Al Addition to Rapid Solidified Mg-Cu-Rare Earth Alloys

S. ROZENBERG; F. AUDEBERT; M. GALANO; I. VERGARA; C, MENDIVE

Cancún

Simposio; NANOMAT 2015; 2015

NANOMAT & TMS

Rapid solidified Mg based alloys are of interest for industrial applications as a structural material and also for hydrogen storage. Particularly, Mg-Cu-Rare Earth alloys have shown very high forming ability, some compositions can be obtained with full amorphous structure with thickness of mm size. However, their brittle behavior limits their industrial applications. Different strategies can be applied to improve the ductility of an amorphous alloy. It has been proposed that the Al addition to Mg-Cu-Rare Earth alloys can retain the glass forming ability and improve ductility. Moreover, it was also observed that Al can also improve the hydrogen absorption and desorption kinetic reactions. Thus Al appears as a key alloying element for the rapid solidified alloys.In the present work, the Al effect in substitution of Cu in the Mg65Cu25MM10 (at%,MM: mischmetal) was studied. Samples up to 15at% Al were prepared by splat cooling technique and their microstructure and stability were characterised by means of X-ray diffraction and differential scanning calorimetry. The mechanical properties were characterised by micro and nano indentation obtaining the Young?s modulus and hardness values. The samples were fractured and fracture analysis was performed by means of scanning electron microscopy. It was observed that the crystallization temperature slightly increases with the Al addition; the amorphous phase with different Al content has an average Young?s modulus value of ~55GPa; and the microhardness increases with the Al the content in the amorphous and crystallized samples. However, the crystallized samples showed higher microhardness values than the amorphous alloys. All the rapid solidified samples showed a brittle fracture surface with the exception of the alloy containing 10at% Al which showed ductile vein patterns which are characteristics of ductile metallic glasses.Results show that the partial Cu substitution by Al can improve the stability and mechanical properties of the amorphous Mg65Cu25MM10 alloy.