Abstrakt
Novel Mg-2Y-2Gd-1Ca alloy was processed by extrusion or equal channel angular pressing (ECAP) to analyse the effect of the microstructure on ignition temperature, mechanical properties and corrosion resistance. The ignition temperature measured by a linear heating experiment in the electric furnace was found to be ALMOST EQUAL TO 950 °C, regardless of the microstructure of processed materials.
The ignition temperature of the alloy is 300 °C higher than that of as-cast magnesium, thanks to the presence of alloying elements and the formation of the stable oxide. Thermogravimetry analysis and differential thermal analysis revealed that the onset of the oxidation process is ALMOST EQUAL TO 50 °C below this temperature.
Partially recrystallised microstructure after extrusion led to a good combination of strength and ductility of the studied alloy. On the other hand, ECAP-processed material is characterised by a higher strength but lower ductility.
Initial corrosion attack is significantly affected by the processing technique, but the difference diminishes within the first day of immersion in 3.5% NaCl solution, and the corrosion rate is comparable after one week of immersion. The only difference is in the distribution of the corrosion attack, which is more localised in extruded samples because of the occurrence of larger Mg2Ca particles compared to the ECAP-processed one.