Influence of Electrostatic Field on the Microstructure and Mechanical Properties of AZ91 Mg Alloy during Ageing Treatment

The effects of electrostatic field on the microstructure and mechanical properties of AZ91 alloy during ageing treatment are studied. It is shown that electrostatic field can modify the precipitate distributions. With the help of electrostatic field (intensity 4 kV cm(-1)), the continuous precipitate (CP) is refined, whereas the discontinuous precipitate (DP) is suppressed to some extent. The tensile yield strength of peak-aged AZ91 alloy is improved from 156 to 169 MPa. The mechanism by which the electrostatic field modifies the precipitate distributions is discussed via the resistivity data combined with the classical theory of vacancy-dominant diffusion. It is shown that the electrostatic field probably enhances the bulk diffusion and then improves the competitiveness of CP against DP.