Mo0.5NbHf0.5ZrTiAl, Mo0.5NbHf0.5ZrTiSi0.5Al and Mo0.5NbHf0.5CrZrTiAl (molar ratio) refractory high entropy alloys (RHEA) were prepared by vacuum arc melting. The influences of Si and Cr on microstructure and properties of RHEA were investigated. Three RHEA all contain BCC1 phase. Si addition promotes the formation of M5Si3 intermetallic compound, and the microstructure of Si0.5Cr0 RHEA consists of M5Si3 blocks and BCC1 + M5Si3 eutectics. Cr addition leads to the formation of Cr2Nb type Laves phase, and two BCC dendrites exist in Si0Cr RHEA. The compressive strength of Si0.5Cr0 and Si0Cr RHEA increased by about 102% and 85%, respectively, compared to Si0Cr0 one. The oxidation resistance of RHEA is improved by adding Si while dramatically degraded by adding Cr.
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