Comparison of Amorphous and Nanocrystalline Alloys

Iron-based amorphous alloys are competing with silicon steel in the industrial frequency and medium frequency fields. Compared with silicon steel, iron-based amorphous alloys have the following advantages and disadvantages.
1) The saturation flux density Bs of iron-based amorphous alloys is lower than that of silicon steel.
However, at the same Bm, the loss of iron-based amorphous alloys is smaller than that of 3% silicon steel with a thickness of 0.23mm. It is generally believed that the reason for the low loss is that the iron-based amorphous alloy strip is thin and has a high resistivity. This is only one aspect. The more important reason is that iron-based amorphous alloys are amorphous, and the atomic arrangement is random. There is no magnetocrystalline anisotropy caused by the directional arrangement of atoms, and there is no grain boundary that produces local deformation and composition offset. Therefore, the energy barrier that hinders the movement of domain walls and the rotation of magnetic moments is very small, and it has unprecedented soft magnetism, so the magnetic permeability is high, the coercive force is small, and the loss is low.
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 though it is heavy, for the power frequency transformer of the same capacity, the loss of the core using iron-based amorphous alloy is 70%~80% lower than that using silicon steel.
4) Considering the loss, the total evaluation price is 89%.
Assuming that the load loss (copper loss) of the power frequency transformer is the same, and the load rate is also 50%. Then, in order 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?8 times that of the iron-based amorphous alloy transformer. Therefore, the weight, cost and price of iron-based amorphous alloy power frequency transformers, which are generally accepted by the domestic public, are 130% to 150% of those of silicon steel power frequency transformers, which does not meet the performance-price ratio principle required by the market. Two comparison methods have been proposed abroad. One is to find the weight and price of copper and iron materials used in the two power frequency transformers under the same loss conditions and compare them. The other method is to reduce the wattage of the loss of iron-based amorphous alloy power frequency transformers and convert them into currency for compensation. The no-load loss per watt is converted into 5 to 11 US dollars, equivalent to 42 to 92 yuan. The load loss per watt is converted into 0.7 to 1.0 US dollars, equivalent to 6 to 8.3 yuan. For example, a 50Hz, 5kVA single-phase transformer with silicon steel core is quoted at 1,700 yuan/unit; the no-load loss is 28W, calculated at 60 yuan/W, which is 1,680 yuan; the load loss is 110W, calculated at 8 yuan/W, which is 880 yuan; then, the total evaluation price is 4,260 yuan/unit. The price of iron-based amorphous alloy core is 2,500 yuan/unit; the no-load loss is 6W, which is equivalent to 360 yuan; the load loss is 110W, which is equivalent to 880 yuan, and the total evaluation price is 3,740 yuan/unit. If the loss is not considered, the price of 5kVA iron-based amorphous alloy power frequency transformer is 147% of that of silicon steel power frequency transformer. If the loss is considered, the total evaluation price is 89%.
5) Iron-based amorphous alloy has stronger resistance to power waveform distortion than silicon steel
Now the loss of power frequency power transformer core material is tested under a sine wave voltage with a distortion of less than 2%. The actual power frequency power grid distortion is 5%. In this case, the loss of iron-based amorphous alloy increases to 106% and the loss of silicon steel increases to 123%. If the high-order harmonics are large and the distortion is 75% (such as power frequency rectifier transformer), the loss of iron-based amorphous alloy increases to 160% and the loss of silicon steel increases to more than 300%. It shows that the iron-based amorphous alloy has stronger resistance to power waveform distortion than silicon steel.
6) The magnetostriction coefficient of iron-based amorphous alloy is large It
is 3 to 5 times that of silicon steel. Therefore, the noise of iron-based amorphous alloy power frequency transformer is 120% of the noise of silicon steel power frequency transformer, which is 3 to 5dB larger.
7) The price of iron-based amorphous alloy strip is 150% of 0.23mm3% oriented silicon steel
in the current market, and 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. In addition, the magnetic core of iron-based amorphous alloy is generally manufactured by a special manufacturer. Silicon steel magnetic core is generally manufactured by transformer manufacturers. According to the above comparison, as long as a certain production scale is reached, iron-based amorphous alloy will replace part of the silicon steel market in electronic transformers within the power frequency range. In the medium frequency range of 400Hz to 10kHz, even if new silicon steel varieties appear, iron-based amorphous alloy will still replace most of the silicon steel market with a thickness of less than 0.15mm. It is worth noting that Japan is vigorously developing FeMB amorphous alloys and nanocrystalline alloys, whose Bs can reach 1.7-1.8T, and the loss is less than 50% of the existing FeSiB amorphous alloys. If used in industrial frequency electronic transformers, the working magnetic flux density can reach more than 1.5T, and the loss is only 10%-15% of silicon steel industrial frequency transformers, which will be a more powerful competitor to silicon steel industrial frequency transformers. Japan expects to successfully trial-produce FeMB amorphous alloy industrial frequency transformers in 2005 and put them into production.

Amorphous 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, so they have obvious advantages in high-power electronic transformers. In 50kHz to 100kHz electronic transformers, the loss P0.2/100k of iron-based nanocrystalline alloys is 30~75W/kg, and the P0.2/100k of iron-based amorphous alloys is 30W/kg, which can replace part of the ferrite market.