Simulation of pre-precipitation in Ni75Al14Mo11 alloy by microscopic phase-field model

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.