Microstructure and Mechanical Properties of Low-Density, B2-Ordered AlNbZrTix Multi-Principal Element Alloys

Abstract

Low-density multi-principal element alloys (MPEAs) combining a high specific strength and considerable ductility have remained a research hotspot, due to their promising prospects for energy-saving industrial applications. Light Ti-containing AlNbZrTix (x = 1−3) MPEAs were designed and prepared by induction melting and annealing. As the Ti content increases, the microstructure of these MPEAs evolves from dual phase (B2-ordered and Zr5Al3-type structure) into a single-phase B2-ordered structure, while the density reduces by ~8.7%, from ~5.85 g·cm−3 (x = 1) to ~5.34 g·cm−3 (x = 3). Unexpectedly, the AlNbZrTix (x = 1, 2, 3) alloys possess high specific yield strengths of ~270 kPa·m3·kg−1, ~221 kPa·m3·kg−1, >208 kPa·m3·kg−1, along with excellent fracture strains of ~17.8%, 21.8%, and >50%, respectively. These combined compressive properties are superior to the reported data of most BCC/B2-dominant MPEAs. The deformation mechanism of the B2-ordered structure is explained as a dislocation-based mechanism, accompanied by antiphase domains. Here, the effect of Ti on the microstructure and compressive properties of AlNbZrTix MPEAs was investigated, providing scientific support for the development of advanced low-density materials.