Effect of heat treatment on wear and corrosion behaviour of ZE41 magnesium alloy

In the present study, T5 heat treatment was performed on ZE41 magnesium alloy, and the effect of altered microstructure on wear, friction and corrosion behaviour was evaluated. After the heat treatment, smaller grain size (91 +/- 10 mu m) was measured compared with the base alloy (110 +/- 12 mu m). Increased tensile strength from 156.4 +/- 9.4 to 172.8 +/- 8.9 MPa was achieved after the heat treatment. Owing to smaller grains and formation of precipitates, heat-treated alloy exhibited better wear resistance compared to as-cast alloy, and a 22% reduction in the wear rate was observed. Abrasion, oxidation and delamination were observed as the dominant wear mechanisms. The enhanced corrosion resistance of heat-treated alloy as reflected with lower corrosion current density (7.29 +/- 1.25 mu A cm-2) compared with base alloy (18.87 +/- 2.13 mu A cm-2) is attributed to the microstructural modification and the presence of zinc- and zirconium-rich regions at the centre of the grains. Furthermore, the corroded surface morphology indicates localised intergranular and micro-galvanic corrosion. The corrosion rate was reduced by 2.6 times after the heat treatment. The results demonstrate the improved tribocorrosion behaviour of heat-treated ZE41 alloy suitable for light weight structural applications. Dans l'& eacute;tude courante, on a effectu & eacute; un traitement thermique T5 sur l'alliage de magn & eacute;sium ZE41 et l'on a & eacute;valu & eacute; l'effet de la microstructure modifi & eacute;e sur le comportement & agrave; l'usure, au frottement et & agrave; la corrosion. Apr & egrave;s le traitement thermique, on a mesur & eacute; une plus petite taille de grains (91 +/- 10 mu m) compar & eacute;e & agrave; l'alliage de base (110 +/- 12 mu m). Apr & egrave;s le traitement thermique, on a obtenu une r & eacute;sistance & agrave; la traction plus & eacute;lev & eacute;e de 156.43 +/- 9.4 MPa & agrave; 172.79 +/- 8.9 MPa. En raison d'une granulom & eacute;trie plus fine et des pr & eacute;cipit & eacute;s d & eacute;velopp & eacute;s dus au vieillissement, l'alliage trait & eacute; thermiquement pr & eacute;sentait une meilleure r & eacute;sistance & agrave; l'usure compar & eacute;e & agrave; l'alliage brut de coul & eacute;e et l'on a observ & eacute; une r & eacute;duction de 22% du taux d'usure. On a observ & eacute; l'abrasion, l'oxydation et le d & eacute;laminage comme m & eacute;canismes d'usure dominants. La r & eacute;sistance & agrave; la corrosion am & eacute;lior & eacute;e de l'alliage trait & eacute; thermiquement, telle que r & eacute;fl & eacute;chie par une densit & eacute; du courant de corrosion plus faible (7.29 +/- 1.25 mu A cm-2) compar & eacute;e & agrave; l'alliage de base (18.87 +/- 2.13 mu A cm-2), est attribu & eacute;e & agrave; la modification microstructurale et & agrave; la pr & eacute;sence d'une r & eacute;gion riche en zinc et en zirconium au centre des grains. De plus, la morphologie de la surface corrod & eacute;e indique une corrosion intergranulaire et micro-galvanique localis & eacute;e avec des piq & ucirc;res de corrosion dans les deux alliages. Cependant, le taux de s & eacute;v & eacute;rit & eacute; de la corrosion dans l'alliage trait & eacute; thermiquement est relativement plus faible avec de plus petites piq & ucirc;res. Le taux de corrosion a & eacute;t & eacute; r & eacute;duit de 2.6 fois apr & egrave;s le traitement thermique. Les r & eacute;sultats d & eacute;montrent le comportement am & eacute;lior & eacute; & agrave; la tribocorrosion de l'alliage ZE41 trait & eacute; thermiquement, appropri & eacute; aux applications structurelles l & eacute;g & egrave;res.