| Abstract Scope |
Body-centered-cubic (BCC) high-entropy alloys (HEAs) revealed improved high temperature resistance compared to face-centered-cubic HEAs and superalloys [Lee2021]. The brittleness of most refractory HEAs (RHEAs) at room temperature, however, limits their application. As an example, the equimolar NbMoCrTiAl alloy was reported having little ductility up to 600 °C [Chen2016]. One exception of BCC-RHEAs is the equimolar TiNbHfZrTi alloy, which shows notable ductility at room temperature [Senkov2015, Dirras2016]. To understand the influence of microstructure on their deformation behaviors under different loading conditions, a series of micro-mechanical experiments including nanoindentation, micro-cantilever and micro-pillar tests were conducted on both alloys. The NbMoCrTiAl alloy, unexpectedly, exhibits significant ductility in the micro-mechanical experiments, especially in the single-crystalline micro-pillar compression tests along the <100> and <110> crystal orientations. Remarkable deformation features, such as slip bands and kink bands, were observed, and the alternating slip and kink processes support the strain achieved >35% comparable to Senkov alloy. |