Study On The Magnetocaloric Effect Of Lanthanum Iron Silicon-based Magnetic Alloy Materials

In today's technologically advanced,many technical fields are inseparable from cooling technology,and refrigeration technology plays an important role in the development of human society.However,the refrigeration materials used in the conventional gas compression refrigeration technology still have problems such as serious environmental pollution,low efficiency,and high energy consumption.Therefore,there is an urgent need that a new refrigeration technology instead of traditional gas compression refrigeration technology.At present,magnetic refrigeration technology has received wide attention from people.It is a new type of refrigeration technology that uses the magnetocaloric effect of magnetic materials to achieve refrigeration.Compared with the traditional gas compression refrigeration technology,magnetic refrigeration has many advantages,such as:high efficiency,low energy consumption,low noise,green environmental protection,etc.Over the past 20 years,great progress has been made in research on magnetic refrigeration technology,many giant magnetocaloric effect materials have been found.Among these magnetocaloric materials,the La(Fe Si)₁₃ alloy of cubic Na Zn₁₃ structure has a large magnetic entropy change,a continuously adjustable Curie temperature,a low production cost,a relatively stable chemical property,and a high saturation magnetization and many other advantages are favored.In particular,the La(Fe Co Si)₁₃B_x alloy is a new type of magnetic refrigerating material of La(Fe Si)₁₃ series with cubic Na Zn₁₃ structure.Its Curie temperature near the room temperature,which not only has the huge entropy change,but also is easy to be industrially synthesized.It is expected to become Standard working medium for future room temperature magnetic refrigerators.In this paper,from the practical application point of view,the low-cost industrial purity raw materials are used to improve the ratio of the existing magnetic refrigerating working material La(Fe Co Si)₁₃ alloy,which is to replace the alloy system with Ce,Nd and Ni elements.The effects of substitution elements on the magnetocaloric effect of La(Fe Co Si)₁₃B_0.25 alloy were investigated by La and Fe methods.In this paper,a series of alloy ingots with different element ratios were prepared by suspension smelting method.After proper heat treatment,a block structure alloy sample was prepared by shearing.It is found through experiments that the replacement of La by Ce/Nd can reduce the Curie temperature of the system but not reach the room temperature.At the same time,the adiabatic temperature change value tends to decrease with the increase of the replacement element content,which is not conducive to room temperature magnetic refrigeration working medium.However,Ni substitution of Fe can linearly increase the Curie temperature of the system and reach near room temperature,although magnetic entropy change and relative cooling power(RCP)also decrease with the increase of the content of replacement elements,but the adiabatic temperature change value changes.Not significantly beneficial as a room temperature magnetic refrigeration refrigerant.Moreover,the magnetic properties of La(Fe_0.92Ni_0.02Co_0.06)_11.4Si_1.6B_0.25 alloy are not only dependent on the electric field strength but also the thermal hysteresis along with the electric field strength.It increases and decreases and its magnetic entropy changes almost unchanged.