Comparison of Amorphous and Nanocrystalline Alloys -

Iron-based amorphous alloys are competing with silicon steel in the field of power frequency and intermediate frequency. Compared with silicon steel, iron-based amorphous alloy has the following advantages and disadvantages. 1) The saturation magnetic flux density Bs of iron-based amorphous alloy is lower than that of silicon steel. However, under the same Bm, the loss of iron-based amorphous alloy is smaller than that of 0.23mm thick 3% silicon steel. It is generally believed that the reason for the small loss is the thin thickness of the iron-based amorphous alloy strip and the high resistivity. This is only one aspect. The main reason is that the iron-based amorphous alloy is amorphous, and the atomic arrangement is random. There is no magnetocrystalline anisotropy caused by the directional arrangement of atoms, and there is no crystal that produces local deformation and composition shift. grain boundaries. Therefore, the energy barrier that hinders domain wall motion and magnetic moment rotation is very small, and it has unprecedented soft magnetism, so it has high magnetic permeability, small coercive force, and low loss. 2) The filling factor of the iron-based amorphous alloy core is 0.84~0.86. 3) The working magnetic flux density of the iron-based amorphous alloy core is 1.35T~1.40T, and that of silicon steel is 1.6T~1.7T. The weight of the iron-based amorphous alloy power frequency transformer is about 130% of the weight of the silicon steel power frequency transformer. However, even if the weight is heavy, for a power frequency transformer of the same capacity, the loss of the iron-based amorphous alloy core is 70% to 80% lower than that of silicon steel. 4) Considering the loss, the total evaluation price is 89%. It is assumed that the load loss (copper loss) of the power frequency transformer is the same, and the load rate is also 50%. Then, to make the iron loss of the silicon steel power frequency transformer the same as that of the iron-based amorphous alloy power frequency transformer, the weight of the silicon steel transformer is 1 to 8 times that of the iron-based amorphous alloy transformer. Therefore, the average domestic people agree that regardless of the loss level of the transformer, the weight, cost and price of the iron-based amorphous alloy power frequency transformer are generally discussed, which is 130% to 150% of the silicon steel power frequency transformer, which does not meet the market requirements. The principle of performance-price ratio. Two methods of comparison have been proposed abroad. One is to calculate the weight and price of copper and iron materials used in two power frequency transformers under the same loss conditions, and compare them. Another method is to reduce the wattage of the loss of the iron-based amorphous alloy power frequency transformer and convert it into currency for compensation. The no-load loss per watt is converted into US$5-11, which is equivalent to RMB 42-92. The load loss per watt is converted into USD 0.7-1.0, which is equivalent to RMB 6-8.3. For example, a silicon steel magnetic core for a 50Hz, 5kVA single-phase transformer is quoted at 1700 yuan/set; the no-load loss is 28W, calculated at 60 yuan/W, which is 1680 yuan; the load loss is 110W, calculated at 8 yuan/W, is 880 yuan; then, the total evaluation price is 4260 yuan/unit. The iron-based amorphous alloy magnetic core is quoted at 2,500 yuan/set; the no-load loss is 6W, which is converted into RMB 360; the load loss is 110W, which is converted into RMB 880, and the total evaluation price is 3,740 yuan/set. If the loss is not considered, the quotation is calculated alone, and the 5kVA iron-based amorphous alloy power frequency transformer is 147% of the silicon steel power frequency transformer. If loss is considered, the total appraised price is 89%. 5) The ability of iron-based amorphous alloys to resist power waveform distortion is stronger than that of silicon steel. Now the test of the loss of the magnetic core material of the power frequency power transformer is carried out under the sine wave voltage with a distortion of less than 2%. The actual power frequency grid distortion is 5%. In this case, the iron-based amorphous alloy loss increased to 106%, and the silicon steel loss increased to 123%. If the high-order harmonics are large and the distortion is 75% (such as a power frequency rectifier transformer), the loss of the iron-based amorphous alloy increases to 160%, and the loss of silicon steel increases to more than 300%. It shows that the ability of iron-based amorphous alloy to resist power waveform distortion is stronger than that of silicon steel. 6) The magnetostriction coefficient of iron-based amorphous alloy is large, which is 3 to 5 times that of silicon steel. Therefore, the noise of the iron-based amorphous alloy power frequency transformer is 120% of the noise of the silicon steel power frequency transformer, which is 3~5dB larger. 7) The price of iron-based amorphous alloy strip is 150% of 0.23mm3% oriented silicon steel. In the current market, it is about 40% of 0.15mm3% oriented silicon steel (after special treatment). 8) The annealing temperature of iron-based amorphous alloy is lower than that of silicon steel The annealing temperature of iron-based amorphous alloy is lower than that of silicon steel, and the energy consumption is small, and the core of iron-based amorphous alloy is generally manufactured by a specialized manufacturer. Silicon steel cores are generally manufactured by transformer manufacturers.
According to the above comparison, as long as a certain production scale is reached, iron-based amorphous alloys will replace part of the silicon steel market in electronic transformers within the power frequency range. In the mid-frequency range of 400Hz to 10kHz, even if new silicon steel varieties appear, iron-based amorphous alloys will still replace most of the silicon steel market with a thickness below 0.15mm.
It is worth noting that Japan is vigorously developing FeMB-based amorphous alloys and nanocrystalline alloys. Its Bs can reach 1.7-1.8T, and the loss is less than 50% of the existing FeSiB-based amorphous alloys. If it is used in power frequency electronic transformers , the working magnetic flux density reaches above 1.5T, and the loss is only 10% to 15% of the silicon steel power frequency transformer, which will be a more powerful competitor of the silicon steel power frequency transformer. Japan is expected to successfully trial-produce FeMB series amorphous alloy power frequency transformers in 2005 and put them into production. Amorphous and nanocrystalline alloys are competing with soft ferrites in the medium and high frequency fields. In 10kHz to 50kHz electronic transformers, the working magnetic flux density of iron-based nanocrystalline alloys can reach 0.5T, and the loss P0.5/20k≤25W/kg. Therefore, it has obvious advantages in high-power electronic transformers. In the 50kHz to 100kHz electronic transformer, the iron-based nanocrystalline alloy loss P0.2/100k is 30-75W/kg,
Iron-based amorphous alloy P0.2/100k is 30W/kg, which can replace part of the ferrite market.