Characterization of the stages of mechanical alloying of the La, Ce, Nd, Pr, Ni, Sn system

CERON-HURTADO, N.M.; ESQUIVEL, M.R

Ciudad de Buenos Aires

Congreso; CONGRESO SAM/CONAMET 2009; 2009

Asociación Argentina de Materiales

The stages present during the low energy mechanical alloying of a mixture of La0,25Ce0,52Nd0,17Pr0,06 , Ni and Sn were identified and characterized. The morphology of the particles was analyzed by scanning electron microscopy (SEM). The identity of the crystalline phases was studied by X-ray diffraction (XRD) and the elemental composition of reactants and products was analyzed by Energy Dispersive Spectroscopy (EDS).  The initial stage occurs between 0 and 30 h. It is controlled by the fracture of the larger particles of both La0,25Ce0,52Nd0,17Pr0,06 and Sn. The intermediate stage is observed for integrated milling time values (tm) between 30 h and 50 h. It is affected by both fracture and cold welding. The former larger particles of La0,25Ce0,52Nd0,17Pr0,06 serve  as a matrix for Sn and Ni and the formation of a initial rich -lanthanide structure is observed. For tm values between 50 h and 70 h, the final stage is observed. Both fracture and cold welding shares control of the process and the formation of La0,25Ce0,52Nd0,17Pr0,06(Ni4,70Sn0,3) is obtained. At larger integrated milling time values (70h < tm <100h), the completion stage is reached, the particles of the alloy are refined and the processing shifts from mechanical alloying to mechanical milling.