Possibility of obtaining refractory high-entropy AlTiZrVNb alloys from metal oxides

We consider a new method for the preparation of refractory high-entropy alloys (HEAs) AlTiZrVNb, which consists in the joint aluminothermic reduction of metals from their oxides. It was determined that V and Nb undergo reduction to a greater extent, and about 90% of their amounts transfer into the metal phase. Metals Ti and Zr undergo reduction to a lesser extent, with 76 and 50% of their amounts transitioning into the metal phase, respectively. The obtained alloy has a multiphase structure consisting of C14 Laves phases, Zr5Al3-type phases, and a B2-type ordered phase, which plays the role of a matrix. The microhardness of the alloy is 6.37 GPa, which is similar to the values of refractory HEAs. The structure of the obtained alloy has a similar structure throughout its bulk, namely, coarse-grained with a number of pores, partly filled with non-metallic inclusions of aluminum oxide.

Automated summary

We have successfully prepared AlTiZrVNb high-entropy alloys using a joint aluminothermic reduction method. V and Nb undergo higher reduction extent, with about 90% of their amounts transferring into the metal phase, while Ti and Zr undergo lower reduction extent, with 76% and 50% of their amounts transitioning into the metal phase, respectively. The obtained alloy has a multiphase structure consisting of C14 Laves phases, Zr5Al3-type phases, and a B2-type ordered phase, which serves as the matrix. The microhardness of the alloy is 6.37 GPa, comparable to that of refractory HEAs. The structure of the obtained alloy exhibits a similar coarse-grained feature throughout its bulk, with some pores partly filled with non-metallic aluminum oxide inclusions.