Available Technology

A Computational Approach to Homogenizing Nickel-Based Single Crystal Alloys

An innovative approach has been developed to improve the thermal processing of advanced Nickel (Ni) single crystal alloys. The method employs thermodynamic and kinetic modeling to efficiently predict and optimize superalloy homogenization resulting in materials with superior properties. Significantly, the subject approach allows the homogenization process to be tailored for the desired end-use of the superalloy, while minimizing effort and cost. This technology is available for licensing and/or further collaborative research with the U.S. Department of Energy’s National Energy Technology Laboratory.
Ni-based superalloys are a unique class of metallic materials possessing an exceptional combination of high temperature strength, durability and resistance to degradation in corrosive or oxidizing environments. Such characteristics make Ni-based superalloys ideal for application in harsh environments such as aircraft and power-generation turbines, rocket engines and chemical processing plants. Optimal superalloy performance requires thermal processing subsequent to manufacture and prior to use. This processing typically involves homogenization heat treatment to evenly distribute the alloying elements throughout the superalloy microstructure, minimizing the adverse, performance-reducing effects of solute non-uniformity. Next to superalloy composition, the homogenization is the primary method of tailoring a superalloy for optimal performance in its intended use. Traditionally, the homogenization process has been performed ina time-consuming, costly, empirical manner. This is a particularly daunting task given that typical Ni-based superalloys contain 10 to 15 alloying elements and uniform chemistry is highly critical to performance. In light of this, researchers at NETL have developed a computationally-based approach to homogenization heat treatment of Ni-based superalloys that delivers consistent levels of homogenization in a time and cost-effective manner. Briefly, the Scheil module of Thermo-Calc software is employed to predict the as-cast, superalloy-specific microstructure (i.e., unique microsegregation of the alloying components) present within the superalloy. The subsequent segregation profiles are read into DICTRA, a software package for simulating diffusion in multicomponent alloys, to refine the homogenization treatment. This allows for a simulated heat treatment of the superalloy casting. Significantly, the ‘computational homogenization’ incorporates the resulting heat-induced redistribution of the alloying elements, successively raising the heat treatment temperatures until the desired level of homogenization is achieved. The result is the identification of a homogenization strategy that provides optimal results in hours, not days, as with conventional empirical methods.
Patent Number: 
U.S. Patent Pending
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