Main Classification Of High-temperature Alloys

The traditional classification of high-temperature alloy materials can be based on the following three methods: by the type of matrix element, the type of alloy strengthening, and the material forming method.
1. By type of matrix element
(1) Iron based high-temperature alloy
Iron based high-temperature alloys, also known as heat-resistant alloy steels. Its matrix is Fe element, and a small amount of Ni, Cr and other alloy elements are added. Heat resistant alloy steel can be divided into martensite, austenite, pearlite, ferrite heat resistant steel, etc. according to its normalizing requirements.
⑵ Nickel based high-temperature alloy
The nickel content of nickel based high-temperature alloys is more than half, which is suitable for working conditions above 1000 ℃. By adopting a solid solution and aging processing process, the creep resistance and compressive yield strength can be greatly improved. Analyzing the high-temperature alloys used in high-temperature environments, the scope of using nickel based high-temperature alloys far exceeds the usefulness of iron based and cobalt based high-temperature alloys. At the same time, nickel based high-temperature alloys are also the largest in production and usage in China. Many turbine blades, combustion chambers, and even turbochargers use nickel based alloys as preparation materials. Over the past half century, the high-temperature resistance of materials used in aviation engines has increased from 750 ℃ in the late 1940s to 1200 ℃ in the late 1990s. This significant improvement has also led to the rapid development of casting processes, surface coatings, and other aspects.
(3) Cobalt based high-temperature alloy
Cobalt based high-temperature alloys are based on cobalt, with a cobalt content of approximately 60%. At the same time, elements such as Cr and Ni need to be added to improve the heat resistance of high-temperature alloys. Although this type of high-temperature alloy has good heat resistance, due to the relatively low production of cobalt resources in various countries, processing is difficult, and the amount used is not large. Usually used for high-temperature conditions (600~1000 ℃) and high-temperature components subjected to extreme complex stress for a long time, such as working blades, turbine discs, combustion chamber hot end components, and aerospace engines. In order to achieve better heat resistance, it is generally necessary to add elements such as W, MO, Ti, Al, and Co during preparation to ensure its superior thermal and fatigue resistance.