Fractural behavior in the transitional region of laser-clad Al–Fe bronze on Al–Si alloy under tensile loading

Abstract

The laser-clad Al–Fe bronze coating on a eutectic Al–Si alloy produced by a 2-kW CO 2 laser displays a special transitional region. The Cambridge S250MK3-type SEM equipped with a tensile stage was employed to test the bond strength and then to investigate the fracture behavior in this special transitional region. The bond strength was mainly influenced by scanning velocity, that is, an increase of scanning velocity from 6 to 14 mm s −1 resulted in a linear increase of the bond strength but the scanning velocity over 14 mm s −1 caused a sharp drop. Dynamic observations of the fractural process showed that the cracking initiated in the needle-like structure layer (i.e. CuAl 2-rich layer) and the propagation of cracks prefer in CuAl 2-rich layer to in the others. The reason of the influence of scanning velocity on the bond strength has been explained finally.