Effects of silicon content on properties of gas-atomized Fe-Si-Cr powders
Fe-Si soft magnetic composites, SMC have some advantages such as excellent dc current superimposed permeability and low core loss over ferrite and Fe-Si bulk cores.
The effects of heat treatment condition and Si distribution on order-disorder transition in high Si steels
The decomposition and formation of ordered phases in steels with 5 to 6.5 %Si were investigated by a combined analysis of TEM and electrical resistivity measurements in order to determine the optimal heat treatment conditions for removal of ordered phases. TEM diffraction pattern study revealed that B2 ordered phase in 6.5 %Si steel was sufficiently dissolved by heat treatment at 850 °C for 1 h, and then rapidly re-formed during cooling. The critical cooling rate, above which the suppression of B2 phase formation was possible, increased rapidly with Si content higher than 5.6%. DO3 phase appeared only in the case of as-cast samples containing Si content as high as 6.5%. The measurement of electrical resistivity change during the heat treatment showed that the atomic movement was substantially spurred above 800 °C, resulting in an active order-disorder transition. The removal of solidification segregation is necessary to reduce the amount of B2 ordered phase in the as-cast or hot-rolled state, to lower the heat treatment temperature for dissolution of B2 ordered phase, and to shorten the heat treatment time.
The Effect of Atomic Ordering on the Magnetic Properties of Fe-Al Alloys
The effect of atomic ordering on the magnetic properties of Fe-Al alloys has been studied for the specimens with different compositions. The so-called “double-Curie point” phenomenon has been studied at a magnetic field strength of 242 Oe: the behavior of the magnetization in this temperature range is different from that observed at lower magnetic field strengths, and Pal and Tarnoczi's interpretation, which is based on the demagnetizing field caused by the formation of a finely dispersed paramagnetic Fe 3 Al ordered phase, cannot apply to this case. There is some evidence that the Curie temperature of FeAl ordered phase is higher than that of Fe 3 Al ordered phase, and at high Al concentrations both of these temperatures are lower than the Fe 3 Al-FeAl transformation temperature. The difference in the paramagnetic behavior between the FeAl ordered phase and disordered phase has been observed and discussed.