Hafnium additions to MAR M 200 enable reliable directional solidification by improving grain boundary strength and oxide scale adhesion, allowing the alloy to achieve the superior creep properties of DS columnar-grain structures. MAR M 200 + Hf retains the high tungsten and cobalt content of the base alloy while delivering better resistance to oxidation spallation under cyclic thermal conditions. Qualified under PWA 1422 and DMD 0484-32, it is a standard DS blade material for aerospace and military gas turbine engines.