La?Fe,Si?₁₃Al_0.3Alloy Magnetocaloric Effects And Refrigeration Capacity Analysis

Magnetic refrigeration with solid magnetic materials as refrigerant is an environmentally friendly and efficient refrigeration method,which is a typical energy saving and emission reduction project.The principle is that magnetic materials exothermic when isothermal magnetization and endothermic when adiabatic demagnetization.Magnetic refrigeration is highly valued by scholars at home and abroad.In particular,La(Fe_xSi_1-x)₁₃3 magnetic refrigeration materials have been widely studied in recent years due to the high magneticaloric effect,low price and large reserves of materials.However,the magnetic transition point?T_c?of La(Fe_xSi_1-x)₁₃3 alloy is far lower than room temperature,and the poor mechanical properties of the material hinder its practical application.The T_c increased to near room temperature by hydrogen absorption or replacement of Fe with Co,and the T_c is continuously adjustable.However,its mechanical properties,magnetic phase change temperature region and cooling capacity are lower than that of metal gadolinium.In this paper,microelement Al was added into La?Fe,Co,Si?₁₃3 and La/Ce?Fe,Mn,Si?₁₃H_y alloys,the structure,magnetic transition point?T_c?,magneticaloric effect,mechanical properties and cooling capacity are been researched.Using industrial pure raw materials,LaFe_11.92-xCo_xSi_1.08Al_0.3.3 and La_0.75Ce_0.25Fe_11.75-xMn_xSi_1.25Al_0.3H_y alloy samples were prepared by high frequency levitation melting furnace.The kilogram LaFe_11.92-xCo_xSi_1.08Al_0.3.3 alloys were prepared by medium frequency induction furnace.The main phase was NaZn₁₃3 with a small amount of rich La phase and?-Fe phase after annealed.The results showed that the LaFe_11.92-xCo_xSi_1.08Al_0.3.3 alloy with trace Al had a large isothermal magnetic entropy change??35?S_m?and adiabatic temperature change(?35?T_ad)?1.5T?,but the?35?S_m and?35?T_add were slightly lower than the alloy without Al.With the increase content of Co and the magnetic phase transition point?T_c?increased,?35?T_add and?35?S_m all decreased.The compressive strength of LaFe_11.12Co_0.8Si_1.08.08 alloy was slightly improved by adding trace Al element.The?35?T_add and?35?S_m of the La_0.75Ce_0.25Fe_11.75-xMn_xSi_1.25Al_0.3H_y alloy with trace Al are large,but which are lower than that of the alloy without Al.With the increase the content of Mn,T_c,?35?T_add and?35?S_m all decreased.Trace Al element was added to LaFe_11.92-xCo_xSi_1.08.08 and La_0.75Ce_0.25Fe_11.75-xMn_xSi_1.25H_y alloy,the half-peak breadth increased,although the?35?T_add and?35?S_m both decreased,the refrigeration capacity did not decrease,on the contrary,it increased.LaFe_11.92-xCo_xSi_1.08Al_0.3.3 or La_0.75Ce_0.25Fe_11.75-xMn_xSi_1.25Al_0.3H_y alloy were used for refrigeration,and multiple magnetic transformation point?T_c?series alloys were required to be arranged and superposition together to reach the cooling temperature zone covered by metal Gd.