Effect of Si content on interfacial reaction and properties between solid steel and liquid aluminum

The effect of Si content on the microstructures and growth kinetics of intermetallic compounds (IMCs) formed during the initial interfacial reaction (<10 s) between solid steel and liquid aluminum was investigated by a thermophysical simulation method. The influence of Si addition on interfacial mechanical properties was revealed by a high-frequency induction brazing. The results showed that IMCs layers mainly consisted of eta-Fe2Al5 and theta-Fe4Al13. The addition of Si reduced the thickness of the IMCs layer. The growth of the eta phase was governed by the diffusion process when adding 2 wt.% Si to the aluminum melt. When 5 wt.% or 8 wt.% Si was added to aluminum, the growth was governed by both the diffusion process and interfacial reaction, and ternary phase tau(1)/tau(9)-(Al,Si)(5)Fe-3 was formed in the eta phase. The apparent activation energies of the eta phase decreased gradually with increasing Si content. The joint with pure aluminum metal had the highest tensile strength and impact energy.