Determination of the vacancy migration enthalpy by Monte Carlo simulation of the short-range order kinetics by a vacancy diffusion mechanism in Ni-Al alloys.

Abstract

Nickel-based superalloys are used for the manufacture of pieces evolving in hot parts of aircraft engines. They are constituted of a Ni3-Al long-range ordered intermetallic phase dispersed in a short-range order matrix corresponding to a nickel-based solid solution [1]. These materials have the particularity of having a high melting temperature, a relatively low density, a good resistance to oxidation and an extreme hardness [2]. Their performance strongly depends on the structural and dimensional stability (creep). They are therefore conditioned by atomic mobility and the properties of the vacancies. We proposed to study, a series of Nickel based alloys, presenting a short-range order and constituting the matrix' basis of these superalloys. In this work, the isothermal curves of electrical resistivity corresponding to ordering kinetics in a series of Ni-Al alloys, by the Monte Carlo method, were calculated up to the fourth neighbors. We have determined the migration enthalpies of the vacancy in these so-called alloys by the method of slope change [3].