ALLOYS OF THE FE-RH SYSTEM AS A NEW CLASS OF WORKING MATERIAL FOR MAGNETIC REFRIGERATORS

The temperature dependences of initial magnetic permeability, specific heat capacity and magnetocaloric effect in annealed and quenched samples of Fe49Rh51 alloys near the antiferromagnetic - ferromagnetic (AF - F) first-order phase transition have been investigated. The application of a magnetic field of about 2 T to a quenched sample of this alloy at 308.2 K causes a temperature drop of 12.9 K under adiabatic conditions. The magnetocaloric temeprature changes were combined with zero-field specific heat data to construct T - S and T - DELTA(S(m) + S(e)) diagrams for various heat-treated samples of Fe49Rh51 alloys and on the basis of these diagrams the refrigerant capacity of alloys was evaluated. The value of the refrigerant capacity of a quenched sample of the alloy at a field of 1.95 T is 135.22 J kg-1 T-1. This value is significantly greater than the refrigerant capacities of well known magnetocaloric materials. The possibility of using the AF - F transition in FeRh alloys for magnetocaloric refrigeration is assessed.