Abstract: Cast superalloys of the formula P.sub.x Q.sub.y R.sub.z wherein P is an element selected from the group consisting of Fe, Ni, Cr, Co or mixtures thereof, wherein Q is a refractory element selected from the group consisting of Mo, W, Ta or a mixture thereof wherein R is a reactive element selected from the group consisting of Al, Ti, Cb or mixtures thereof, x is from about 65 to about 95 atomic percent, y is from about 1 to about 10 atomic percent, z is from about 1 to about 18 atomic percent and x+y+z is equal to about 100 in the form of thin foil are made ductile by the presence of appreciable amounts of amorphous phase and micro-crystalline, metastable single phase and subsequently boron is deposited as nickel, iron or cobalt boride on the surface of the foil at a temperature below the crystallization temperature of the superalloy. Such foil is especially suited for preplacement in a joining operation such as brazing.