Influence of intermetallic phases and Kirkendall-porosity on the mechanical properties of joints between steel and aluminium alloys

► Reaction layers grow with parabolic kinetics at 450 °C and above. ► The η phase (Al5Fe2) is the dominant component of reaction layers. ► Deformation of base materials affects build-up and growth kinetics of the layers. ► Formation of Kirkendall-porosity embrittles joints with pure Al. ► Thickness of the η phase layer governs tensile strength of joints with Al-Si alloys.