Amorphization in equiatomic high entropy alloys

• Amorphization in FeCrNiMX (M = Co, Mn, Nb, Ti, Zr; X = B, Si) high entropy alloys studied
• All Si containing alloys show significant amorphization.
• No amorphization in Fe–B alloys except for Nb containing alloy
• Slower dissolution of B is responsible for non-amorphization in Fe–B alloys.
• Larger atomic size of Si provides greater driving force for amorphization.

Amorphization behavior in equiatomic high entropy alloys has been investigated. Pseudo-binary FeCrNi–M–B alloys and true equiatomic high entropy compositions FeCrNi–M–Si (M = Co, Mn, Nb, Ti, Zr) have been synthesized using mechanical alloying. Formation of amorphous phase has been confirmed using X-ray diffraction analysis and transmission electron microscopy. All alloys containing Si showed significant amorphization. Fe80B20 is known to be a good glass former, but no amorphous phase was observed in Fe–B based alloys except for FeCrNiNbB. The slower kinetics of dissolution of B in the alloy due to its sluggish diffusivity caused by its higher melting point is attributed to be the reason for the poor amorphization in B containing alloys.