Magnetic Properites in Alloy Systems

Abstract: The attention for materials displaying high magnetocaloric effect (MCE) has grown during the past 30 years. One of the most important properties of MCE is the adiabatic temperature change ( ). The main aim of this work was to develop a method to measure the temperature change ( ) for magnetocaloric materials in a changing magnetic field.  A technique was developed where maximum reached  for Gadolinium was 1.19 K in a changing magnetic field of 1.3 T, however, this is lower value in comparison with previous studies (3.3 K in a changing magnetic field of 1 T, Bjørk, et al., 2010) which makes the developed method not sufficient enough to measure . Furthermore, finding novel materials displaying high MCE is of great interest. MnFePSiB alloys display promising MCE properties but processing method is expensive and time consuming. Therefore, a MnFePSiB compound was simply remelted several times and heat treated to enhance its properties. The MnFePSiB alloy was remelted 1, 2 and 3 times after initial casting. Melting the material 3 times resulted improvement in both the magnetic and magnetocaloric properties due to enhanced homogeneity. The material melted 3 times was further heat treated to improve its magnetic magnetocaloric properties. Heat treating the material for 5 hours at 1373K improved the magnetic entropy change more than 10 times compared to the as cast sample,  was moved closer to room temperature and maximum  of 0.71 K was obtained.