Effect of synergistic microalloying on the microstructural optimization of Mo/NiAl alloy with excellent mechanical properties under rapid non-equilibrium solidification

Abstract

Low room-temperature plasticity and poor high-temperature strength extremely restrain the extensive application of NiAl composites. Herein, our work synergistically optimized the NiAl microstructure via alloying of Mo to relieve imbalance of strength and ductility under rapid non-equilibrium solidification supplemented with the first principle calculation. Remarkably, the addition of Mo significantly refined the microstructure of NiAl–15Mo. Moreover, enhanced by the uniform precipitation Mo phase, the coordinately deformed Mo phase at the grain boundary and the partial Mo solid solution occupied Ni sites, the NiAl–15Mo showed superior strength-ductility. The mechanical properties (σ0.2, σUCS, UT) of NiAl–15Mo composites at room temperature were 944 MPa, 1841 MPa, and 27,068 MPa·%, which were increased by ∼55.3 %, ∼48.7 % and ∼41.0 % compared with the conventional NiAl composites, respectively. In particular, owing to solid-solution Mo atoms restrict the climb of dislocations and the stronger covalent bond orbital hybridization between Ni-3d and Mo-4d, the mechanical properties (σ0.2, σUCS, UT) of NiAl–15Mo at 1000 °C are 212 MPa, 265 MPa and 7922 MPa·%, which has an increase of ∼175.3 %, ∼120.8 % and ∼228.0 %, respectively. This work provides a new perspective to manipulate and coordinate Mo multiple reinforcing ways and achieve the high strength and plasticity of NiAl composites.