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

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

Cancún

Congreso; NANOMAT 2015; 2015

Instituto Politécnico Nacional - ESIQIE, Dept. of Eng. In Metalllurgy & Materials

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