Modification of NiAl–Cr(Mo)–0.15Hf alloy by Sc addition

The effect of Sc addition on the microstructure and room temperature compressive properties of NiAl–28Cr–5.85Mo–0.15 (at pct) Hf−x (wt pct) Sc (x = 0,0.05, 0.1, 0.2, 0.3) alloys was investigated. The results show that appropriate Sc addition (no more than 0.10 wt pct) leads to the refinement of interlamellar and intercellular spacings of the eutectic NiAl/Cr(Mo) cell, and the improvement of the compressive ductility and ultimate compressive strength at room temperature. When the addition of Sc is more than 0.10 wt pct, the typical NiAl/Cr(Mo) cell structure becomes broken. With the fragment of Cr(Mo) rods embedded in NiAl matrix instead of the alternating NiAl and Cr(Mo) plates, which damages the compressive properties. In addition, when the Sc addition content increases to 0.20 wt pct, Sc-containing phase is found and tentatively identified as ScO.