On the corrosion behaviour of as-cast and heat-treated Mg-RE alloys in 0.9% NaCl solution

Type : Publication
Auteur(s) :  Abdelkader HANNA 1, Lyacine RABAHI 2, Mohamed Amine SOUALILI 3, Achour DAKHOUCHE 4, Djamel BRADAI 5, and Hiba AZZEDDINE
Année :  2020
Domaine : Chimie
Revue : Journal of Metals, Materials and Minerals
Résumé en PDF :  (résumé en pdf)
Fulltext en PDF :  (.pdf)
Mots clés :  Corrosion resistance Heat treatment Magnesium alloy NaCl solution Rare earth

Résumé : 

The microstructure and corrosion behaviour of as-cast and heat-treated Mg-1.44Ndand Mg-1.43Ce (wt.%) alloys in 0.9% NaCl (wt.%) solution were investigated usingelectrochemical tests, X-ray diffraction (XRD) and scanning electron microscopy,combined with energy-dispersive X-ray spectroscopy (SEM-EDS). The as-castmicrostructure of both alloys revealed the presence of second phases. Heat treatmentat 535°C for 6 h led to a more uniform distribution of the second phases in Mg-1.44Ndalloy and their dissolution along the grains boundaries in the Mg-1.43Ce alloy. As aresult, the corrosion resistance was improved in the heat-treated alloys. Accordingly,the corrosion resistance values for the heat-treated alloys were much higher than thoseof the as-cast alloys, indicating that the heat-treated alloys were less susceptible to thecorrosion. Also, the heat-treated Mg-1.43Ce alloy seems to have very good corrosionresistance (26890 Ω cm 2 ) compared to the Mg-1.44Nd alloy (6156 Ω·cm 2 ) bypreventing pitting corrosion along the grains boundaries. The corrosion product wasmade up mainly of magnesium hydroxide Mg(OH) 2 and magnesium oxide MgO andmore uniform corrosion morphology were found in the heat-treated alloys.