Eet Caculating Investigation Of γ/γ’phases Crystal’s Cohesive Energies And Re Partitioning Behaviors In CMSX-4Superalloy

Nickel-base single crystal superalloys were widely used in the manufacturing field of advantage aeroengine turbine blade for its excellent high temperature properties. With the development of high thrust-weight ratio turbine, call for higher tempreature resisitance materials. Compared with the frist generation Ni-base single crystal superalloy, the bearing temperature of second and third generation single crystal superalloys increased30℃and60℃respectively. The additon of3%wt and6%wt Re are the major characteristics of the2th and3th generation superalloys. Re is a scarce and extremely expensive elements that lead to the costing increased about70%within per3%wt Re which bring a great challenge to the development of Ni-base superalloy. Recently, the researchers are trying to decrease the costing of the experimental design by using the theoretical calculation method. However, there are more than10elements in the superalloy, it makes the alloy system too complex to calculating by Frist-Principle Method. Compared with it, the Empricial Electron Theory (EET) is more simple calculating method, which base on the calculating of valence electron, and achieved material composition design finally. In this paper, a series of calculation modles were setted up by using method of EET. Base on the calculating results of electron values of the alloy, the cohesive energies were calculated and the distribution of Re atom was investigated too. All these are the fundamental work for the design of Nickel-base alloys which might be helpful for the futher development of the superalloys.In this paper,6defferent kinds of calculationg models were setted up, and the probable Re-containing crystal cells in y phase and y’phase, which define as Ni、Ni3Re、Ni3.75Re0.25and Ni3Al、Ni2AlRe、Ni3Al0.75Re0.25, were denoted respectively. Different kind of crystal formation enthalpy were calcuated. The result indicated that melting point of y-Ni3Re crystal is about348℃higher than γ’Ni2AlRe. It increases the value of valence electrons on [110] and [101] direction, and brings a significantly increasing of solid solution strengthening effect when the Re atom is inside the cell. At the same time, Re increases the atom status value of σN(from3and42to2341and762respectively) which increased the stability of the alloy system; During the process of soildifying, both the y phase and y’phase will precipitate Ni3Re and Ni2AlRe crystal previously. As the temperature decreasing, the Ni3.75Re0.25and Ni3Al0.75Re0.25crystal would appeared by the diffussion ultimately, and Re atom will occupy the corner positon of the crystal. Re improve the y interphase electron density (from33.316to37.9426) and the difference of electron density (from0%up to12.985%) of γ/γ-Ni interphase significantly. All these evidence indicated that Re increase the bonding and stability of the interface.