Cocktail effect on RT5-type (R = rare earth, T = 3d transition metal) high entropy intermetallic compounds

Abstract

The alloys with normal compositions of (Sm1/2Ce1/2)(Co1/3Cu1/3Ni1/3)5, (Sm1/2Pr1/2)(Co1/3Cu1/3Ni1/3)5, (Sm1/2Nd1/2)(Co1/3Cu1/3Ni1/3)5, (Sm1/3Ce1/3Pr1/3)(Co1/3Cu1/3Ni1/3)5, and (Sm1/3Ce1/3Nd1/3)(Co1/3Cu1/3 Ni1/3)5 are designed by mixing RCo5, RNi5, and RCu5 for studying their cocktail effects. These designed alloys are prepared by vacuum Arc melting technology. Their single-phase characteristics are experimentally confirmed by X-ray diffraction and scanning electron microscope with energy dispersive spectrum, and also theoretically confirmed by the reported single-phase formation rule of high entropy alloys: atomic radius difference within 6%, nonpositive mixing enthalpy, and high configuration entropy above 1.50R. The designed alloys are suggested to be the high entropy intermetallic compounds due to their single-phase characteristics and high configuration entropy. The magnetic cocktail effect is observed in magnetic measurements. These intermetallic compounds show low-temperature magnetic transition and field-induced ferromagnetic characteristics. The cocktail effect is suggested to be modulated by the spins with random directions at rare earth and transition metal sublattices caused by mixture of the multiple individual RCo5, RNi5, and RCu5 intermetallic compounds.