Realizing Spherical High Entropy Alloy (HEA) AM Powders for Aerospace Applications

Since last decade there have been numerous attempts to develop alloys that can push the limits of the performance of conventional alloys in aerospace. Once such class is High entropy Alloys (HEA). These alloys constitute equi-atomic concentrations of at least 5 elements with no base element. High concentrations of alloying elements tend to increase entropy of mixing of such alloys, hence the term HEA. Research has indicated that HEAs possess exceptional properties that can exceed conventional alloys in performance for aerospace and hypersonic applications. However, solubility limits of the alloying elements in such large concentrations coupled with a vast difference in their melting temperatures pose a hurdle in manufacture of HEAs with traditional melt-based methods. Solid state Mechanical Alloying (MA), where the alloying carried out by mechanical force, has been extensively used for investigations of HEAs. Powders obtained by MA are flaky with very low Apparent Density (AD) with virtually “no flow”. Such powders limit the consolidation method to Spark Plasma Sintering (SPS), which is not an industrial process preventing use of HEAs commercially.

6Ks UniMelt microwave plasma process can combine with MA to produce highly dense, satellite free and free flowing spherical HEA powders for use in AM. Castheon, a manufacturer serving aerospace recently printed the world’s first AM HEA printed part using L-PBF using spherical HEA powder combining the elements – 25Fe-17Cr-17Co-17Ni-16Cu. In this demonstration 2 of the 5 materials had a differing melt temperature of 900 degrees highlighting the versatility of HEA powder. This process brings HEA to mainstream manufacturing by opening up infinite opportunities of alloy design to support Industry 4.0.

In this session we will discuss the process of creating HEA’s the process for printing HEA and discuss and solicit from participants the different HEA possibilities and advantages for their applications.