The studies of high-temperature and short-time annealing, phase transition process, and magnetic property for LaFe11.7Si1.3 compound

The high-temperature phase transition is analyzed according to the DSC of as-cast LaFe11.7 Si-1.3 compound and the X-ray patterns of LaFe11.7Si1.3 compounds prepared by high-temperature and short-time annealing. Large amount of 1: 13 phase begins to appear in LaFe11.7Si1.3 compound annealed near the melting point of LaFeSi phase (about 1422 K). When the annealing temperature is close to the temperature of peritectic reaction (about 1497 K), the speed of 1: 13 phase formation is the fastest. The phase relation and microstructure of the LaFe11.7Si1.3 compounds annealed at 1523 K (5 h), 1373 K (2 h) + 1523 K (5 h), and 1523 K (7 h) + 1373 K (2 h) show that longer time annealing near peritectic reaction is helpful to decrease the impurity phases. For studying the influence of different high-temperature and short-time annealing on magnetic property, the Curie temperature, thermal, and magnetic hystereses, and the magnetocaloric effect of LaFe11.7Si1.3 compound annealed at three different temperatures are also investigated. Three compounds all keep the first order of magnetic transition behavior. The maximal magnetic entropy change Delta S-M (T, H) of the samples is 12.9, 16.04, and 23.8 J kg(-1) K-1 under a magnetic field of 0-2 T, respectively.