Wetting behaviour of copper on an iron aluminide alloy

The wetting of a Cr-containing, iron aluminide alloy (FA-129) by molten copper was investigated in order to evaluate the possibility of brazing this alloy with copper-based filler metals. The results show that good wetting of the iron aluminide substrate by the copper is obtained within 2 mins. The spreading mechanism is controlled by Al diffusion through the protective Al2O3 layer on the substrate, into the copper drop. This alloying of copper reduces its melting point: liquid formation and spreading were observed at temperatures as low as 1070 °C. The molten metal penetrates the grain boundaries of the Fe3Al and facilitates decohesion of the structure. In conjunction with this grain dissolution, copper precipitates were produced within the Fe3Al grains.