Abstract
Laser cladding using Al–30%Si alloy powder was applied to AZ91D alloy in order to improve its wear resistance. Area fractions of Mg2Si and Mg17Al12 compounds with relatively high hardness in the cladding layer with a width of 4 mm and a depth of 1.5 mm increase with an increase in powder feeding rate, resulting in high hardness of the cladding layer. Further increase in the powder feeding rate leads to crystallization of aluminum solid solution with low hardness as the matrix phase of the cladding layer together with further increase in the area fraction of Mg2Si compound. Therefore, the hardness of the obtained cladding layer becomes lower than that of the layer consisted of Mg17Al12 + Mg2Si compounds. With the increase in an area fraction of Mg2Si compound, the wear depth of the cladding layer decreases, but that of Cr-plated pin used as the counter material increases. The wear depth of the layer consisting of large area fraction of Mg2Si compound and aluminum solid solution is almost same as that of the Cr-plated pin, and this indicates good wear resistance. However, the presence of a large amount of brittle Mg17Al12 compound causes flaking of Mg2Si compound during wear test and, consequently, leads to ternary abrasive wear, resulting in large wear depth.
