An axle assembly that includes an axle housing assembly, a differential disposed in the axle housing assembly, an input pinion, a pair of axle shafts and a heat sink. The input pinion is coupled to the axle housing assembly and is configured to transmit a rotary input to the differential. The axle shafts are coupled to the differential and housed in the axle housing assembly. The heat sink is coupled to the axle housing assembly and is formed of a material having a thermal conductivity that is greater than that of the axle housing assembly. The heat sink does not consist entirely of a chrome plating, a zinc plating or a cadmium plating. A cover for an axle assembly is also provided.