Abstract
Intermetallic compounds (IMCs) distributed at the interface reduce the bonding strength of Mn–Cu–Al alloy/430 stainless steel (430SS) brazed joints. Here, we investigated the formation mechanism of IMCs to improve the reliability of brazed joints. Mn–Cu–Al high-damping alloy and 430SS were induction-brazed assisted by Cu–34Mn–6Ni–6Sn filler metal and borate brazing flux. Shapeless IMCs were observed to be distributed in chains at the joint interfaces. Moreover, shear cracks propagated along the IMC chains. The IMCs were determined to be (Fe, Cr, Mn)2B; elemental B could only come from the brazing flux according to the materials used for brazing. We propose that IMC formation consists of four stages: (i) substrate dissolution and filler metal diffusion, (ii) B2O3 reduction, (iii) IMC nucleation, and (iv) needle growth and chain distribution of IMC.
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