Corrosion behavior of alloy AM50 in semi-solid cast and high pressure die cast states in cyclic conditions

Artikel i vetenskaplig tidskrift, 2015

The atmospheric corrosion behavior of the Mg-Al alloy AM50 produced by high pressure die casting (HPDC) and a semi-solid metal (SSM) technique was studied under alternating wet-dry conditions for up to 672 hours. The alloy AM50 in the SSC state was fabricated using rheocasting (RC) technique in which the slurry was prepared by the newly developed RheoMetal process. To simulate the real-world atmospheric environment, the exposure program included a 6 hour wet phase (including rain with 0.5 % NaCl), a 2.5 hours transition phase followed by a 15.5 hours dry phase at 50°C and 70% relative humidity (RH). The results showed that the RC alloy was substantially less prone to corrosion than the HPDC material in the cyclic wet/dry atmosphere. Based on the gravimetric results and microstructural characterization studies, this was attributed to a lower fraction of porosity and to the barrier role of β phase particles in the RC.