Superalloys or high-performance alloys are the materials able to withstand extreme temperatures that would destroy conventional metals like steel, titanium and aluminum. The term "superalloy" was first used shortly after World War II to describe a group of alloys developed for use in turbo-superchargers and aircraft turbine engines that required high performance at elevated temperatures. The range of applications for which superalloys are used has expanded too many other areas and now includes aircraft and land-based gas turbines, rocket engines, chemical, and petroleum plants. They are particularly well suited for these demanding applications because of their ability to retain most of their strength evenafter long exposure times above 650°C. Their versatility stems from the fact that they combine this high strength with good low-temperature ductility and excellent surface stability .    Ni base superalloys are multicomponent complex alloys which, in addition to Ni, contain varying amounts of Cr, Mo, W, Nb, Al, Ti, Ta, Re, Hf, Zr, B, and C to obtain the desired strength, oxidation resistance, and corrosion resistance. Superalloys have been under intense and continuing development since the early 1940’s.  At 1950’s, the evolution from wrought to conventionally cast,  to directionally solidified to single crystal turbine blades has yielded a 250°C increase in allowable metal temperatures, and cooling developments have nearly doubled this in terms of turbine entry gas temperature. An important recent contribution has come from the alignment of the alloy grain in the single crystal blade, which has allowed the elastic properties of the material to be controlled more closely. These properties in turn control the natural vibration frequencies of the blade .  Nickel-based alloys can be either solid solution or precipitation strengthened. Solid solution strengthened alloys, such as Hastelloy X, are used in applications requiring only modest strength. In the most demanding applications, such as hot sections of gas turbine engines, a precipitation strengthened alloy is required. Most nickel-based alloys contain 10-20% Cr, up to 8% Al and Ti, 5-10% Co, and small amounts of B, Zr, and C. Other common additions are Mo, W, Ta, Hf, and Nb. In broad terms, the elemental additions in Ni-base superalloys can be categorized as being: · γ formers (elements that tend to partition to the γ matrix).  · γ' formers (elements that partition to the γ ' precipitate).  · Carbide formers.  · Elements that segregate to the grain boundaries such as B, C, and Zr .   The widespread use of superalloys in turbine engines coupled with the fact that the thermodynamic efficiency of turbine engines is increased with increasing turbine inlet temperatures . A superalloy is a metallic alloy which is developed to resist most of all high temperatures, usually in cases until 70 % of the absolute melting temperature.  All of these alloys have an excellent creep, corrosion and oxidation resistance as well as a good surface stability and fatigue life.  The main alloying elements are nickel, cobalt or nickel – iron, which can be found in the 8th group of the periodic system of the elements. Fields of application are found particularly in the aerospace industry and in the nuclear industries, e.g. for engines and turbines.  The development of these advanced alloys allows a better exploitation of engines, which work at high temperatures, because the Turbine Inlet Temperature (TIT) depends on the temperature capability of the material which forms the turbine blades.  Ni based superalloys have an austenitic face-centered cubic, which delivers advantages such as: · better mechanical properties · higher modulus · higher solubility of alloying elements · systems of gliding plane