A composite metal ingot having two or more lengthwise alloy layers including adjacent first and second layers respectively formed of an aluminum-manganese alloy and an aluminum alloy of a different composition wherein the interface between the first and second layers is in the form of a substantially continuous metallurgical bond characterized by the presence of particles of one or more intermetallic compositions containing manganese from the first layer dispersed within a region of the second layer adjacent the interface, the first and second layers having been formed by applying the alloy for the second layer to a self-supporting surface of the first layer while the self-supporting surface is at a temperature between the solidus and liquidus temperatures of the first layer alloy.