THE EFFECT OF PROCESSING PARAMETERS ON 1:13 PHASE FORMATION AND MAGNETIC PROPERTIES OF (LA_(1-X)CE_X)(FE_(1-Y)MN_Y)_(11.5)SI_(1.5)H_Z COMPOUNDS

摘要

Large-scale preparation of La_(0.7)Ce_(0.3)Fe_(11.28)Mn_(0.22)Si_(1.5) compounds was investigated by melt-spinning technique.rnThe microstructure of as-cast ribbon affects the 1:13 phase formation greatly in the annealing process: finer grains of as-castrnribbon accelerate 1:13 formation but lead to the growth of α-Fe grains in the annealing process. Homogeneous and stablernLa_(0.7)Ce_(0.3)Fe_(11.28)Mn_(0.22)Si_(1.5)H_z is obtained after annealing ribbons under H_2 atmosphere of 0.2 MPa at 623 K for a week. Afterrnbeing kept for one year, there is almost no change in the Tc of the hydrides. Short preparation time, homogeneous and stable T_C,rnand large MCE suggest that large-scale (La_(1-x)Ce_x)(Fe_(1-y)Mn_y)_(11.5)Si_(1.5)H_z hydrides are promising candidates of magnetocaloricrnmaterials for practical magnetic refrigeration near room temperature.