한국주조공학회

In the present work, the corrosion properties of Mg-xSn (x = 1, 3, 5, 7 and 9 wt.%) alloys have been investigated. Potentiodynamic polarization and immersion tests were carried out in 3.5% NaCl solution of pH 7.2 at room temperature to measure the corrosion properties of Mg-xSn (x = 1, 3, 5, 7 and 9 wt.%) alloys. With increase of the Sn contents, the volume fraction of the Mg2Sn phase was increased. The corrosion rate of Mg-xSn alloys was increased up to 7 wt.%Sn and decreased above 9 wt.%Sn. Initiation of galvanic site during immersion mainly occurred at Mg/Mg2Sn interface and propagation went into α-Mg. For this reason, corrosion properties of Mg-xSn (added from 1 wt.%Sn to 7 wt.%Sn alloys) alloys are decreased because the galvanic site was increased with increasing Sn addition. In Mg 9wt.%Sn alloy, however, the corrosion site were changed from Mg/Mg2Sn interface to α-Mg/M2Sng interface in lamellar structure. Preferentially corrosion of α-Mg/M2Sn interface in lamellar structure impeded corrosion propagation went into α-Mg.

Permanent mold casting, Mg-Sn alloy, Corrosion properties.