Oxide Dispersion Strengthened Medium Entropy Alloy
materials and coatings
Oxide Dispersion Strengthened Medium Entropy Alloy (LEW-TOPS-151)
An Additively Manufactured Alloy Tailored for High-Temperature Applications
Innovators at the NASA Glenn Research Center have developed a new oxide dispersion strengthened medium entropy alloy (ODS-MEA) using additive manufacturing (AM). ODS alloys, in which nano-scale ceramic particles are distributed within the metal, were originally developed to enhance mechanical properties (e.g., creep resistance, tensile strength, microstructure integrity) at extreme temperatures. Thus, such alloys show promise for metal components of gas turbines, rocket engines, nuclear reactors and other high-temperature applications. However, the conventional mechanical alloying process to produce such alloys is highly inefficient, time-consuming, and costly. By contrast, NASA's ODS-MEA is designed for production via selective laser melting. The alloy can be fabricated into complex geometries and is resistant to stress cracking and dendritic segregation. It is not susceptible to deleterious phase changes when exposed to extreme temperatures and requires limited post-processing.
NASA's ODS-MEA maintains properties up to 1100°C and is not susceptible to deleterious phase changes when exposed to extreme temperatures, an issue ubiquitous to Ni- based superalloys such as Inconel-625 and Inconel-718. Yttria particles are dispersed throughout the alloy to maximize strength and creep resistance at high temperatures using a novel fabrication technique. This technique employs an acoustic mixer to stir nano-scale Yttria oxide powder within a metallic matrix powder, creating a film of Yttria surrounding the larger metallic powder particles. Solid components are then produced from this mixture via SLM, during which the laser disperses the Yttria particles throughout the microstructure. Ultimately, the process eliminates the many expensive and time-consuming steps in the production of ODS alloys via traditional mechanical alloying. NASA's process has been shown to fabricate components with 10x improvement in creep rupture life at 1100°C and provides a 30% increase in strength over what is currently possible with 3D printed parts. The new ODS-MEA composition may find applications where ODS alloys are currently used (e.g., those involving extreme thermal environments). Applications may also include areas where such properties are desirable but the resource-intensive nature and/or inability to produce highly complex geometries via conventional processes ultimately renders their use uneconomical or infeasible. Such uses include gas turbine components (for which increasing inlet temperature enables improved efficiency) for power generation, propulsion (rockets, jet engines, etc.), industrial processes, nuclear energy applications, and sample preparation equipment in the mining and cement production industries, among many others.
- Maintains properties up to 1100°C: the alloy is not susceptible to deleterious phase changes when exposed to extreme temperature environments (a common issue for Ni-based superalloys), and is resistant to stress cracking and dendritic segregation
- Highly efficient process: eliminates numerous expensive and time-consuming steps for producing ODS alloys via conventional mechanical alloying processes and requires limited post-processing
- Adaptable, improved fabrication: the oxide-based process has been shown to fabricate components with 10x improvement in creep rupture life at 1100°C and a 30% increase in strength relative to current 3D-printable metal parts
- Aerospace: high-temperature components for space launch systems and jet turbine engines
- Industrial machinery: chemical processing and waste processing systems
- Marine: turbine engines for ships
- Oil and gas: oil refining process
- Power: steam turbines and gas turbines for electricity generation, structural components for solar thermal power plants, heat exchangers for nuclear reactor systems
- Propulsion: rockets, jet engines, etc.
materials and coatings
"Microstructural and Mechanical Characterization of a Dispersion Strengthened Medium Entropy Alloy Produced Using Selective Laser Melting," Smith, T.M., et al., November 17, 2019,https://ntrs.nasa.gov/citations/20200000360