Precipitation behaviors of spray formed AZ91 magnesium alloy during heat treatment and their strengthening effect

Microstructures of spray formed AZ91 magnesium alloy sample were characterized in various heat treatment conditions. Different precipitation behavior of spray formed AZ91 magnesium alloy were studied at different heat treatment temperatures and hours. It is easier for the spray forming extruded alloy to occur DP nucleation near grain boundary due to fine grain size and high solute content. Network of β-Mg17Al12 was broken and fine continuous precipitates appeared quickly and occupied throughout the sample at 365 °C heat treatment. Strengthening effect of discontinuous precipitates with small planar distance is better than that of coarse continuous precipitates.