Electrochemical cold drawing of in situ Mg2Sip/AM60B composite: A comparison with the AM60B alloy

The effects of different processing parameters on the electrochemical cold drawing of Mg2Sip/AM60B composites were investigated; the AM60B matrix alloy was also examined for comparison. Compared with the drawing in air, the electrochemical cold drawing significantly reduced both the drawing force and surface hardness of the composite, although the electrochemical plasticization of the composite was relatively lower than that of the alloy, owing to the presence of Mg2Si particles. Notably, the drawing force continuously decreased as the current density increased; however, when the bar surface was largely covered by a thick corrosion layer, this behavior changed, i.e., the drawing force increased rather than decreased. The surface layer could result in an increase in friction force between the bar and the die, and might create a barrier to dislocation exit. Increasing the drawing speed decreased the plasticizing action by reducing the electrochemical reaction time between electrolyte and material surface and by enhancing work hardening per unit time. This phenomenon was more evident in the composite because of both the lower corrosion rate and higher work-hardening rate, due to the presence of Mg2Si particles.