Abstract
Authors have already reported that in the Cu brazing to dissimilar C steels a "dissolution and deposit of base metal" took place —that is, the low C steel base metal dissolves into molten Cu filler metal and, simultaneously, the dissolved Fe deposits as the columnar Fe-Cu-C alloy phase from the high C steel boundary at a constant brazing temperature.
In this paper, the deposit mechanism of the columnar Fe-Cu-C alloy was investigated and results obtained were as follows;
(1) The columnar Fe-Cu-C alloy consists of 9 to 12%Cu, I to 2%C and the rest Fe.
(2) When C steel dissolves into molten Cu, the Fe and C atoms will form the massive Fe-C associated compound.
(3) The deposit of the columnar Fe-Cu-C alloy will be caused by that the low C Fe-C associated compound, which is dissolved into molten Cu from the low C steel, combines with C at the high C steel boundary to convert into the high C Fe-C associated compound due to larger bonding force of Fe-C compared with that of Fe-Cu in liquid Cu and its concentration exceeds the equilibrium quantity.
