Study On Interface Evolution Rule Of Ni₇₅Al_xV_25-xAlloy During Precipitation Process By Microscopic Phase-Field Method

Nickel-base alloy is widely used in the hot end components in manufacturing industryfor its high-temperature creep degeneration resistance, fatigue resistance, oxidation resistance,corrosion resistance, etc. As a strengthening phase, the coherent and orderly A3B intermetalliccompound which is formed by adding aluminum, tungsten, molybdenum, cobalt and otherelements can further improve the high-temperature strength of the alloy. The interface of thematerials, such as grain boundaries, phase boundaries and surfaces, has important influenceon the mechanical property of the materials. Meanwhile, elastic energy can cause precipitatesisotropic, and the antisite defect will reduce the stacking fault energy and the antiphaseboundary energy of the alloy, these factors will influence the alloy strength, toughness,plasticity and creep resistance to varying degrees.This paper is based on the microscopic phase-field dynamics model and ternaryNi₇₅Al_xV_25-xalloy is the research object. Using MATLAB language program, a systematicstudy of the ordered phase interface evolution rule is made by simulating the precipitationprocess of the nickel base alloy. The influence of the elastic energy and antisite defect on theinterface evolution is also analyzed in the paper.Through simulating the precipitation process of different concentration alloy at differenttemperature, it is discovered that L12phases, DO₂₂phases and L12phases and DO₂₂phasescan form four, eight, and four interface structure respectively. In which, there are twono-migration interface, in the process of precipitation process, the interface structure remainsunchanged; there are seven migration interface, five of them the interface structure remains the same, and two of them the interface structure changes.The elastic energy changes the morphology of precipitation phase from ellipticityirregular distribution to ribbon regular distribution, and the interface distribution fromirregular random arrangement to obvious orientation; with the increase of the elastic energy,the interface orientation becomes clearer and distributes along the elastic soft direction,forming an arrangement of high degree preferred orientation.In the precipitation process of Ni75Al10V15alloy, elastic energy has no effect on Ll₂cophase interface and the out-phase interface structure between Ll₂phases and DO₂₂phases;when the elastic energy is considered, DO₂₂co-phase interface increases with two interfacestructures,（1 00）_θ//（200）_θand（ 001）_θ//（200）_θ; in the process of Al atoms replacing Vatoms in interface, there is inhibitory action, the greater the elastic energy, the more obviousthe inhibition.With the increase of the Al:V value, the antisite defects of AlNiinαposition decreasesand the antisite defects of V_Ni remains unchanged; both the antisite defects of NiVand AlNiinβposition decreases, and it is easier for Al atoms to occupy theαposition of the DO₂₂structure; two out-phase interfaces between DO₂₂ phases and Ll₂phases are formed at theposition of Ni₃V phase antisite defects.