Abstract:The early precipitation process of Ni₇₅Al₁₄Mo₁₁ alloy was simulated by microscopic phase-field model at different temperatures. The microstructure of the alloy, the precipitation time of L1₀ structure and occupation probability of the three kinds of atoms were investigated. It is indicated that the non-stoichiometric L1₀ (I/II) phases are found in the precipitation process. With the temperature increasing, the appearance time of L1₀ is brought forward. The L1₀ (II) structure always precipitates earlier than the L1₀ (I) structure. Compared with lower temperature, higher temperature brings the formation time of L1₀ phase forward and makes L1₀ phase have a higher order degree. But lower temperature shortens the process time of the L1₀ phase to the L1₂ phase. Al and Mo atoms tend to occupy γ site, Ni atom tends to occupy α and β sites. At the same temperature, Al atom has stronger occupation ability than Mo atom in the same site. Ni, Al and Mo collectively form the composited L1₂ structure.

Key words: Ni₇₅Al₁₄Mo₁₁ alloy; microscopic phase-field model; precipitation incubation period; L1₀(I/II) phase