Effect of Al content on the order of phase transition and magnetic entropy change in LaFe11Co0.8(Si1−xAlx)1.2 alloys

The comparative studies of the effect of partial substitution of Al by Si on the structure and magnetic entropy change in LaFe11Co0.8(Si1−xAlx)1.2 alloys produced by arc-melting followed by long time annealing at 1323 K were performed. The X-ray diffraction analysis revealed almost single phase composition of annealed samples. The high intensity synchrotron radiation was used for studying the thermal evolution of lattice constant of the La(Fe,Co,Si)13 phase. Furthermore, calculations of temperature dependences of Landau coefficients were used to reveal changes in the character of phase transformation at around the Curie temperature.