Introduction
High temperature alloys are a special class of materials that offer a unique combination of mechanical and physical properties. They are suitable for use in a wide range of industrial applications, including those in aerospace, automotive, military and petrochemical industries. High temperature alloys can withstand extreme temperatures and have good creep resistance and fatigue resistance. They possess good resistance to corrosion and oxidation, as well as high strength. A major limitation of these alloys is their susceptibility to brittle fracture at high temperatures due to embrittlement. To improve the fracture properties of high temperature alloys, grain boundary engineering is employed.
Grain Boundary Engineering
Grain boundary engineering is a technique used to modify the microstructure of materials by controlling the grain boundaries of the material. Grain boundary engineering is used to improve the ductility, creep resistance, creep resistance, fatigue resistance and fracture toughness of materials. As the grain boundaries of materials can be adjusted and controlled, it can be used to improve the fracture properties of high temperature alloys. The addition of grain boundary strengthening additives to the alloy can increase fracture toughness and reduce the risk of brittle fracture at high temperatures.
Types of Grain Boundary Strengthening Additives
There are a variety of grain boundary strengthening additives that can be used to improve the fracture properties of high temperature alloys. The most common type of grain boundary strengthening additives is carbide forming elements, such as chromium, molybdenum and tungsten, which form carbides at the grain boundaries. These carbides act as a barrier, preventing the propagation of cracks through the grain boundaries. Other types of grain boundary strengthening additives are carbonitrides, nitrides, borides and silicides. These materials form intermetallic compounds at the grain boundaries, improving the fracture toughness of the alloy.
Conclusion
Grain boundary engineering is a method used to modify the microstructure of high temperature alloys and enhance their properties. This technique is used to improve the fracture properties of the alloy by adding grain boundary strengthening additives. Carbide forming elements, carbonitrides, nitrides, borides and silicides are commonly used as grain boundary strengthening additives. By adding these materials to the alloy, the fracture toughness of the alloy is improved and the risk of brittle fracture at high temperatures is reduced.
