Enhanced impression creep performance of gravity and suction cast Al-12Ce alloy with Si and Mg additions

The current investigation examines the microstructure and impression creep behavior of both gravity and suction-cast Al-12Ce alloy containing 4Si and 4Si+0.4Mg (all in wt%) additions across stress and temperature ranges of 335-480 MPa and 473-548 K, respectively. The Al11Ce3 phase volume fraction, interlamellar spacing (ILS), and aspect ratio decrease when 4Si and/or 0.4Mg are incorporated into the Al-12Ce alloy. However, the aspect ratio and volume fraction of CeAlSi2 phase increased, which was more pronounced in suction casting. The gravity-cast Al-12Ce-X exhibits superior impression creep resistance contrary to Al-12Ce alloy, which further enhanced after suction casting. Remarkably, the suction-cast Al-12Ce-4Si-0.4Mg alloy displays the maximum hardness (38% higher) and highest creep resistance (63% higher) than Al-12Ce alloy. For all the alloys, the prevailing creep mechanism was pipe diffusion-dominated dislocation creep. High creep resistance of suction cast Al-12Ce-4Si-0.4Mg alloy was due to the smallest grain size, less Al11Ce3 phase content, lowest interlamellar spacing, solid solution strengthening by Mg, maximum CeAlSi2 phase content, and highest dislocation density.