Interaction of iron-chromium alloys containing 10 and 25 mass% chromium with liquid aluminium - Part II - Formation of intermetallic compounds

Two intermetallic layers Fe2Al5 and Fe2Al7 occur at the interface between the iron-chromium alloys containing 10 and 25 mass% Cr and the saturated aluminium melt at 700degreesC. Under conditions of simultaneous dissolution in pure liquid aluminium only the Fe2Al5 phase forms an adherent continuous layer, while the Fe2Al7, FeAl3, FeAl6, CrAl7 and other phases exist as inclusions in the aluminium matrix. Dissolution of the Fe Cr alloy base into pure aluminium causes a three-fold decrease in layer thickness compared with the case where no dissolution occurs. A simple equation for evaluating the Fe2Al5 layer thickness during dissolution is proposed. Making the Fe Cr alloy-to-aluminium transition joints, with the mechanical strength of the joint greater than or equal to that for pure aluminium (70-80 MPa), appears to be feasible. (C) 2004 Kluwer Academic Publishers.