Effect of Mg and Si Content on Microstructure and Property of Al-Mg-Si Alloy

The effect of Mg and Si content with fixed Mg/Si ratio on the microstructure and properties of Al-Mg-Si alloy was investigated by mechanical properties testing, intergranular corrosion and electrochemical polarization curve, combined with SEM, EDS, TEM techniques. The experimental results indicate that increasing content of Mg and Si from 0.6wt% and 0.56wt% to 1.6wt% and 1.49wt% can improve mechanical property by promoting the precipitation of metastable β" precipitates. Continuing to increase the content of Mg and Si can coarsen the MgSi phase which would crack easily under stress and lead to the decline of mechanical property. The corrosion resistance of Al-Mg-Si alloy is in inverse proportion to the content of Mg and Si associated with the density of the second phase. Corrosion always occurs in second phase or the matrix around them, while the quantity of second phase is in direct proportion to the element content, which means the alloy with higher content of Mg and Si is more susceptible to be corroded. © 2019, Materials Review Magazine. All right reserved.