Soar's Primary Surface Recuperator (PSR) is a compact, high thermal effectiveness heat exchanger for reducing fuel consumption and increasing the thermal efficiency of gas turbine engines. (Recuperation extracts waste heat from the turbine exhaust stream to heat the compressor discharge air before entry into the combustion system.) Soar's PSR is comprised of thin, folded, corrugated sheets of a stainless steel (eg type 347) in modular units (air cells). Since sheet data are not applicable to thin foils, effort was focused on acquiring creep, tensile, and oxidation data for a variety of stainless and alloy materials. A new thin foil material was created from two separate materials welded together at gage; the advanced alloy would be used only in the hottest sections of the recuperator and the stainless would be used elsewhere to keep the cost down.