Papers by Keyword: Fe-6.5%Si

Abstract: Deposits of the Fe-6.5wt%Si alloy rapidly quenched by spray forming were investigated. The order phase can be either B2 or DO3 depending on annealing treatment conditions. The observation of pairs dislocations indicates the presence of super dislocations and B2 antiphase boundaries (APBs) which affects significantly the soft magnetic properties. The dislocations bound the APBS which yield δ fringes when image 200 superlattice reflections. Samples treated at 700oC for 1 h were oil quenched, this has induced a decreasing of power loss and the TEM micrographs have showed developed 1⁄4 <111> antiphase domain structure in the B2 phase. The magnetic properties were: power loss of 1.59 W/kg and coercive force of 76 A/m, at B=1 T, f=60 Hz. The samples annealed at 1250°C for 1h showed the same interaction between the APBs but better power losses on their magnetic properties. The magnetic properties were: 1.30 W/kg power loss and 40 A/m coercive force, at same conditions described above. This suggests a strong interaction between magnetic properties and antiphase domain structure in the B2 ordered phase. Optical microscopy observations corroborate the magnetic measurement conclusions.

Abstract: Fe-6.5%Si alloy spray formed has the Curie temperature variation measured as a function of the parameters process. In this work the magnetic transition temperature was obtained by Differential Scanning Calorimeter although it can be also gotten by Vibration Samples Magnetometer. The process parameters controlled were gas pressure (P), tube diameter (T) and fly height (H) and the properties analyzed were coercive force, maximum permeability, power loss and Curie temperature. The chemical composition was determined using the Curie temperature. The microstructure of deposits was observed in different conditions of light microscopy, bright field, polarized light and dark field, and the grain size was measured according to ASTM 112-95. The process parameters combination P5T6H360 has produced the minimum power loss of 2.26 W/kg and maximum permeability of 9,000. The Curie temperature measured was 683°C, which indicates a Si content of 6.5wt%.