Abstract: Quaternary carbide Ti₃NiAl₂C ceramics has been investigated as a potential nuclear fusion structural material, and it has advantages in certain aspects compared with Ti₂AlC, Ti₃AlC₂, and Ti₃SiC₂ structural materials. In this paper, quaternary carbide Ti₃NiAl₂C ceramics is pressurized to investigate its structural, mechanical, electronic properties, and Debye temperature. Quaternary carbide Ti₃NiAl₂C ceramics still maintains a cubic structure under pressure (0-110 GPa). At zero pressure, quaternary carbide Ti₃NiAl₂C ceramics only has three bonds: Ti-Al, Ni-Al, and Ti-C. However, at pressures of 20 GPa, 30 GPa, 40 GPa, 60 GPa, and 70 GPa, new Ti-Ni, Ti-Ti, Al-Al, Ti-Al, and Ti-Ti bonds form. When the pressure reaches 20 GPa, the covalent bonds change to metallic bonds. The volume of quaternary carbide Ti₃NiAl₂C ceramics can be compressed to 72% of its original volume at most. Pressurization can improve the mechanical strength and ductility of quaternary carbide Ti₃NiAl₂C ceramics. At 50-60 GPa, its mechanical strength can be comparable to pure tungsten, and the material changes from brittleness to ductility. However, the degree of anisotropy of quaternary carbide Ti₃NiAl₂C ceramics increases with the increasing pressure. In addition, we also investigated the Debye temperature, density, melting point, hardness, and wear resistance of quaternary carbide Ti₃NiAl₂C ceramics under pressure.

Key words: quaternary carbide Ti₃NiAl₂C ceramics, structural properties, mechanical properties, electronic properties, Debye temperature, first-principles