Abstract: The effect of Al content on the solidifying structures of Ni-Al-C self-lubricating material was studied. The mechanical properties and tribological performances were investigated. The results show that when Al content is 4.25%, the graphite content is high, the eutectic graphite is the main morphology and the matrix of the alloy is single γ-Ni(Al) solution. With the increase of Al content, the graphite content and eutectic graphite of solidifying structures deduce, graphite in primary phase has a tendency of spherical transformation. When Al content is 6.85%, the γ-Ni(Al) solution and a small quantity of （γ+γ′） eutectic make up the matrix of the alloy. When the Al contents are 8.13%-9.94%, γ-Ni(Al) solution disappears, the solidifying structures of the alloy are composed of γ′-Ni₃Al, （γ+γ′）and graphite phases. When the Al content is 12.74%, the matrix are γ′-Ni₃Al and Ni₃AlC_0.5 phases with high hardness observed on reticular intergranular in the alloy. The alloys with lower Al content have preferable ductility, improving the Al content is advantage to improve the mechanical robustness and wear-resisting property of materials. The matrix structures of alloy with 8.13%Al consist of （γ+γ′） eutectic phases. The grain size is refined obviously and the comprehensive mechanical properties improve obviously. The wear coefficient and the wear loss rate are little.

Key words: Ni-Al-C alloys； Al content； solidifying structure； mechanical properties; tribology properties