Abstract: An improved combination glass door closure and ducted (e.g., tubular) heat exchanging grate for fireplaces. The combination grate includes a ducted heat exchanger suitable for positioning within a fireplace cavity. The heat exchanger comprises a plurality of hollow, generally parallel, C-shaped heat exchanger members which are carried by a glass door fireplace closure. One end of each of the heat exchanger members is attached to the fireplace closure by means of a sliding or floating seal and means are provided for preferentially directing the flow of air to the centermost heat exchanger members.

Abstract: Powdered austenitic chromium-nickel stainless steel is blended with a powdered metal ferrite stabilizer, such as molybdenum, and the resulting blend is sintered to produce a new steel, namely, an unwrought austenitic-ferritic chromium-nickel alloy having, as sintered, desirably high tensile and yield strength and other desirable properties.