A dual wall cooking vessel is formed by the impact or friction bonding of
the an inner to an outer vessel wherein a laminate of aluminum and copper
layers is disposed between the outer surface of the bottom of the inner
vessel and the inner surface of the bottom of the outer vessel. The
aluminum layers are arranged to surround the copper layer of the
uppermost aluminum layer being the upper aluminum layer being thinner
than the lower aluminum layer and having a slightly smaller diameter than
the copper and aluminum layer. The appropriate dimensions of the aluminum
layers and sequence of welding and bonding operation results in the
co-extrusion of both aluminum layers into a portion of the adjacent
sidewall formed by the gap between the walls of the inner and outer
vessel. This co-extruded layer s of aluminum within the side walls and
the bottom of the vessel improves the heat transfer from the outer vessel
to the inner vessel during cooking, but without significantly diminishing
the insulating properties of the dual wall vessel that serve to keep the
food warm while it is being served.