Ni–Al powder and Ni–Al composite coatings were fabricated by twin-wire arc spraying(TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy(SEM) and energy dispersive spectroscopy(EDS). The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni–Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni_3Al, Al_2O_3, and NiO. The Ni–Al phase and a small amount of Al_2O_3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni–Al composite coatings were characterized by SEM, EDS, X-ray diffraction(XRD), and transmission electron microscopy(TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and Ni Al in addition to a small amount of Al_2O_3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, Ni Al, and Ni_3Al in addition to a small amount of Al and Al_2O_3, and Ni Al and Ni_3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl_3 precipitates and a Ni–Al–O amorphous phase formed in the matrix of the Ni solid solution in the original state. Ni-Al powder and Ni-Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5 wt% Al powder and Ni- 20 wt% Al powder were characterized by scanning electronic microscopy (SEM) The morphology of the Ni-Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni_3Al, Al_2O_3, and NiO. The Ni The microstructures of the twin-wire-arc-sprayed Ni-Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission The results showed that the main phase of the Ni-5 wt% Al coating consisted of Ni solid solution and Ni Al addition to a small amount of Al 2 O 3. The main phase of the Ni-20 wt% Al coating mainly consisted of Ni solid solution, Ni Al, and Ni_3Al in addition to a small amount of Al and Al_2O_3, and NiAl and Ni_3Al intermetallic compounds actually further improved the final wear property of the coatings. TEM analysis showed that fine spherical NiAl_3 precipitates and a Ni-Al-O amorphous phase formed in the matrix of the Ni solid solution in the original state.