Phase Diagrams And Magnetocaloric Properties Of The Dy-Co-Ag Ternary System

With the development of technology, the vapor-compression refrigerators have become ubiquitous in a large number of cooling applications. However, the use of chlorofluorocarbons and hydrochlorofluorcarbon as work fluids has raised serious environmental problems, primarily for the destruction of the ozone layer and the global warming. In addition, the efficiency of the vapor-compression refrigeration systems is not expected to be significantly improved in the future. Recently, magnetic refrigeration technology has attracted more and more attentions due to its advantages in energy saving and environmental concern. It has been demonstrated as a promising alternative for the conventional gas-compression technique which is generally in use today. A lot of works have been carried out to find the proper working materials with a large magnetocaloric effect (MCE) in different temperature regions.Alloys based on the Dy-Co system have been reported to be a candidate material for magnetic refrigeration. In this work, it was investigated the effects of Ag addition on the phase equilibria and magnetocaloric properties of the Dy-Co system. The isothermal section of the Dy-Co-Ag ternary system at 500oC was constructed and the effect of Ag content on the MCE of some Dy-Co alloys was studied.The Dy-Co-Ag alloys were melted in an arc furnace using a non-consumable electrode under the protection of high purity Ar. X-ray diffraction (XRD) was used to characterize the phases in each sample. The phase diagram was built based on the XRD results mainly.The M-T curves of Dy(Co1-xAgx)₂ (x=0, 0.005, 0.01, 0.02, 0.03, 0.05, 0.1) series alloys were measured in a field of 0.1T with a vibrating sample magnetometer (VSM) to determine the Curie temperatures. The isothermal magnetization curves were measured in the field range of 0¹.5T near the Curie temperatures. The magnetic entropy changeâ–³SM was obtained from the isothermal magnetization through numerical calculation. The isothermal magnetization curves of Dy₂(Co1-xAgx)₁₇ (x=0.005, 0.01, 0.02, 0.03, 0.05, 0.1)...