High-temperature alloys are a type of material used in high temperatures and extreme environments. They have excellent high-temperature strength, oxidation resistance, corrosion resistance and other characteristics. They are widely used in aviation, aerospace, energy, chemical industry and other fields. Rare earth elements are one of the commonly used additive elements in high-temperature alloys and have strong effects on purification, micro-alloying and improvement of oxidation resistance.
The application of rare earth elements in high-temperature alloys mainly has three aspects. First of all, rare earth elements serve as purifiers with deoxidation and desulfurization effects, which can reduce the harmful effects of oxygen and sulfur at grain boundaries. Secondly, rare earth elements, as micro-alloying elements, are segregated at grain boundaries and play a role in strengthening grain boundaries. Finally, rare earth elements as active elements can improve the oxidation resistance of the alloy and improve surface stability.
Taking GH1035 alloy as an example, researchers found that mixed rare earth elements have little effect on room temperature tensile properties. However, mixed rare earth elements have a significant impact on durability. The durability life at 700°C and 235MPa is increased from 130 h without mixed rare earths to 500 h with 0.05% mixed rare earths, an increase of up to 4 times, and the durability is extended at the same time. The rate has also increased. As more mixed rare earth elements are added, the durability and plasticity decrease. This is because rare earth elements segregate at the grain boundaries to strengthen the grain boundaries and inhibit the formation and expansion of cracks.
The free energy of formation between rare earth elements and O, N and S is very low, and it is easy to form oxides, nitrides, sulfides and oxysulfides of rare earth elements, which float and are removed from the alloy liquid, thus reducing the oxygen, sulfur and nitrogen content of the alloy. , to achieve the purpose of purifying grain boundaries. At the same time, rare earth elements can also interact with low-melting-point impurities such as As, Pb, Sb, Bi, and Sn in the alloy liquid to generate compounds with higher melting points and be removed. The reduction of gas and low melting point impurity content is beneficial to the improvement of mechanical properties. The application of rare earth elements can also form the core of the alloy’s solidification and crystallization, refine the structure and make the grains smaller, which is beneficial to improving the plastic deformation ability of the alloy.
The combined effect of the above three factors has made the application of rare earth elements in high-temperature alloys more and more widespread. For example, after adding a trace amount of Ce to the K640S alloy, the durability time and durability elongation at 850°C and 205MPa, as well as the high-temperature tensile strength and plasticity at 900°C, are significantly improved. At the same time, when the recycled materials of cobalt-based high-temperature alloy K640S are used, rare earth elements can be added to reduce the impurity content and improve the reuse rate of the material.
In addition, rare earth elements can also form a dense oxide film in high-temperature oxidizing environments to protect the surface of the alloy, thereby improving the oxidation resistance and service life of the alloy. This oxide film can inhibit the diffusion of oxygen and the oxidation reaction of metal, thereby slowing down the oxidation rate of the material and the dissolution rate of the metal.
In general, the application of rare earth elements in high-temperature alloys can improve the oxidation resistance, durability and plastic deformation capabilities of the alloy, and can also purify the alloy liquid and improve the reuse rate of materials. Therefore, rare earth elements have become one of the indispensable additive elements in high-temperature alloys.
Tianjin Anton Metal Manufacture Co., Ltd. is a company specializing in the production of various nickel-based alloys, Hastelloy alloys and high-temperature alloy materials. The company was established in 1989 with a registered capital of 10.0 million, specializing in the production and sales of alloy materials. Anton Metal’s products are widely used in aerospace, chemical industry, electric power, automobile, nuclear energy and other fields, and can also provide customized alloy material solutions according to customer needs. If you need to know the price consultation of alloy materials or provide customized alloy material solutions, please feel free to contact the sales staff.
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Post time: Oct-21-2023
