Grain Refinement of the CrMnFeCoNi High Entropy Alloy Cast Ingots by Adding Lanthanum

The effect of lanthanum addition on the grain refinement of CrMnFeCoNi high-entropy alloys (HEAs) was investigated experimentally. When 9.3 pct lanthanum was added, the equiaxed zone faction enlarged sharply from 41.17 to 76.58 pct. The number of grains < 200 µm increased obviously, and the mean grain size in the equiaxed zone decreased from 331 to 144 μm. Compositional undercooling induced by lanthanum addition caused grain refinement of the HEAs.