Enhanced strength-ductility synergy in directionally solidified Ni-27Al alloy via particle reinforced composite structure formation by static magnetic field

The strength-ductility trade -off of Ni3Al alloy is a significant factor that impacts its potential applications. This paper explores the application of a static magnetic field to enhance the microstructure and mechanical properties of Al-rich beta (NiAl)/gamma' (Ni3Al) two-phase Ni3Al alloy during directional solidification. The results revealed that the implementation of a 0.5 T magnetic field led to the formation of oriented NiAl particles with a single crystal Ni3Al composite structure. This novel composite structure exhibited higher yield strength (307.5 MPa), ultimate strength (525.6 MPa), and good ductility (8.2 %), surpassing the sample without a magnetic field by 13.7 %, 16.6 %, and 49 % respectively. These results indicate an excellent combination of strength and ductility. The synergetic improvement of strength and ductility can be primarily attributed to the particulate reinforcement effect and the maintenance of the so-called K-S orientation relationship, which enables dislocation transfer between the plastic gamma'-Ni3Al phase and the brittle beta-NiAl phase. This study provides a promising strategy for obtaining desirable microstructures and properties by utilizing a magnetic field to form a composite structure.