1. Solid solution strengthening
Nickel-based casting high-temperature alloys to enhance the performance of one of the methods is solid solution strengthening, which refers to aluminum, titanium, niobium, tantalum and other alloying elements can be formed with the matrix γ ′ phase alloy into the alloy, resulting in a certain lattice distortion, so as to enhance the strength of the alloy method. This phenomenon of strengthening a metal by incorporating a solute element to form a solid solution is called solid solution strengthening. This type of alloy has excellent oxidation and fatigue resistance properties, the most obvious advantage is the high structural stability, and good thermal plasticity. According to the above characteristics, nickel-based casting high-temperature alloys can be used to manufacture metal parts with large temperature variations, such as: fan blades of aircraft engines, turbine box components.
The United States Haynes company (Hastelloy) in 2005 developed an excellent nickel-based deformation of high-temperature alloys Haynes282, the alloy's operating temperature in the 649 ~ 927 ℃ between, and through the optimization of the composition and the control of the alloy in the content of γ ′, so that the alloy has both good creep strength, thermal stability, and superior machinability and good weldability, which is mainly due to the addition of the alloy in the alloy. This is mainly due to the addition of refractory metal components such as tungsten and manganese in the alloy.
2. Precipitation strengthening
In recent years, researchers have been mostly consistent in their approach to improving the strength and properties of nickel-based cast high-temperature alloys, which has not changed much, even with differences in added materials. In the process of research to improve the strength and performance of the alloy, researchers generally add a little precipitation strengthening elements in the alloy, through the heat treatment process from the alloy organization of the mother phase precipitation of the second phase (γ′, γ″, carbides, etc.), which significantly improves the strength of the alloy. Typical γ′ phase in nickel-based casting high-temperature alloys is Ni3Al or Ni3Ti, which is strengthened by the following two ways: one is to increase the amount of γ′ phase by increasing the content of Ai and Ti elements in the alloy; and the other is to add elements such as Co, W and Mo to improve the strength of the γ′ phase. Through the increase of some elements, the precipitated second phase can effectively inhibit the development and growth of metal material particles. Alloys with this type of strengthening are mostly used to make high-temperature engine components, such as: aero-engine, gas turbine turbine blades and so on.
