Selective electron beam melting of Al0.5CrMoNbTa0.5 high entropy alloys using elemental powder blend

Abstract

High Entropy Alloys (HEAs) is a novel promising class of multi-component materials which may demonstrate superior mechanical properties useful for high-temperature applications. Despite the high potential of HEAs, their production is complicated, using pre-alloyed powders in powder metallurgy route. This significantly complicates development and implementation of refractory BCC solid solution based HEAs. The present paper reports on experiments aiming at production of Al0.5CrMoNbTa0.5 multi-principle alloy using powder bed beam based additive manufacturing. Samples were manufactured using Selective Electron Beam Melting (SEBM) additive manufacturing technique from a blend of elemental powders aiming at achieving microstructure with high configurational entropy. Though it was not possible to achieve completely homogeneous microstructure, the as-printed material was composed of the zones with two multi-component solid solutions, which differed only by Al content confirming in situ alloying. The process parameters optimization was not carried out and the as-print material contained a notable amount of residual porosity. It was possible to reach lower porosity level using heat treatment at 1300 °C for 24 hours, however undesirable alloy composition changes took place. The main conclusion is that the production of the Al0.5CrMoNbTa0.5 multi-principle alloy from elemental powder blends using SEBM technique is achievable, but the process parameter optimization rather than post-process heat treatment should be performed to reduce the porosity of samples.

Hybrid additive manufacturing of steels and alloys

“…Manufacturing of hybrid-like compositionally and functionally graded materials is one of the modern unique options provided by the PBF-systems [13,[76][77][78]. It can be achieved by simultaneous process parameters control and feeding of blended powders.…”

Powder-bed additive manufacturing for aerospace application: Techniques, metallic and metal/ceramic composite materials and trends

“…Traditionally, PB-AM methods are using gas-or plasma atomized powders [7,37] made from pre-alloyed material. But in cases when non-equilibrium material microstructure is desirable (like with BMG, HEA and some other materials), blends of elemental powders can be used [28,30,31,[38][39][40].…”

“…; thermal conductivity of 180-200 W/(m • K) (as in Al), in single crystals up to 470 W/ (m • K); working temperaturemore than 1350°C (as in heatresistant steels); melting/decomposing point is 2830°C; resistance in the oxidizing and reducing environment is higher than that of Ti [89]. PB-AM technologies demonstrate significant potential in manufacturing of composite materials both from the blended powders and pre-agglomerated powders where each grain already contains multiple materials sintered together [28,38,39,90].…”

“…Though the growing interest in the development of new materials for PB-AM is continuously increasing, today's state of the art regarding the trials for in situ alloying in PB-AM aiming at HEAs remains very restricted. Only few reported researches on this matter can be mentioned [22][23][24][25][26][27][28][29]32,39,51,90,[108][109][110][111].…”

“…PB-AM with the high power beams is used for different group of materials: from light metals like Aluminum [5,6] and Titanium alloys [7][8][9][10], to steels [5,[11][12][13], and even refractory Tungsten [14], Tantalum [15], Inconel [16][17][18][19][20][21], high entropy alloys (HEAs) [22][23][24][25][26][27][28][29] and bulk metallic glass (BMG) materials [30][31]. In special literature, the term "additive manufacturing", in relation to both metallic materials and polymers, is more common than 3D-printing commonly used in the news popular literature.…”