Effect of the synergistic effect of Cr and Mo on the solidification microstructure and mechanical properties of NiAl-based high-entropy alloys

To balance the strength and toughness of NiAl-based alloys by coupling multiple strengthening mechanisms, two novel high-entropy alloys (HEAs), Ni_0.35Al_0.3 (CoFe)_0.2Cr_0.15-xMo_x (x=0,0.05), were prepared, and their mechanical properties were explored. First, the addition of Mo induces the shape of the precipitate to change from spherical to acicular. Ni_0.35Al_0.3(CoFe)_0.2Cr_0.1Mo_0.05 has excellent high-temperature mechanical properties. Foremost, the strength is better than that of most Ni-based superalloys, Co-based superalloys and Ni-Co-based superalloys at 873 K. Notably, its yield strength is greater than 1400 MPa. When the temperature reaches 1123 K, the yield strength is still greater than 600 MPa. Moreover, the acicular precipitated phase maintains a co-lattice relationship with the matrix. The synergistic effect of solid solution strengthening and precipitation strengthening significantly enhances the strain hardening ability of the Ni_0.35Al_0.3 (CoFe)_0.2Cr_0.1Mo_0.05 alloy.