Advantages of Nickel-based Super Alloy Powder in High-temperature Applications

In the fields of engines, gas turbines, etc., materials need to withstand extreme temperatures of >700°C, high pressure, corrosion and mechanical stress, which puts forward strict requirements on high-temperature performance. Nickel-based superalloys have become irreplaceable core materials due to their high melting point (>1300°C), excellent high-temperature strength, creep resistance and oxidation resistance. For example, the operating temperature of engine turbine disks and blades can reach 1100°C, while nickel-based alloys can still maintain structural stability. The combination of powder metallurgy and additive manufacturing technology further breaks through the limitations of traditional casting/forging and realizes near-net forming of complex parts.

Alloy Powders Products List

• High-Temperature Alloy Powders
• Stainless Steel Powders
• Precision Alloy Powders
• High-Entropy Alloy Powders
• Other Alloy Powders

Common Advantages of Nickel-based Super Alloy Powders

γ' phase (Ni₃Al/Ti) precipitation strengthening: γ' phase is an ordered face-centered cubic (FCC) structure, which significantly improves high-temperature strength by hindering dislocation movement. For example, the volume fraction of γ' phase in IN738 alloy increases with the increase of Al/Ti content, but too high Al/Ti will cause hot crack sensitivity. The stability of the γ' phase directly affects the alloy's endurance strength. Long-term exposure to temperatures above 649°C may cause the γ' phase in IN718 alloy to transform into a harmful δ phase.

Solid solution strengthening and oxidation resistance: Elements such as Cr, Mo, and Co strengthen the matrix, among which Cr forms a dense Cr₂O₃ oxide layer (thickness of about 3.8–13.9 nm), which effectively blocks oxygen diffusion. Experiments show that the oxidation kinetics of GH202 alloy at 800–900°C follows a parabolic law, dominated by Cr³⁺ diffusion; but after exceeding 1000°C, the oxide film falls off and the protective ability drops sharply. The formation of the Al₂O₃ layer further supplements high-temperature protection, especially in alloys with a Cr content of >15%.

Composition uniformity and defect control: Traditional ingot casting is prone to macrosegregation, while powder metallurgy (such as plasma rotating electrode powdering, PREP) can eliminate segregation and reduce inclusions. FGH95 alloy uses electrostatic separation technology to remove inclusions, and the oxygen content is controlled below 490 ppm, which significantly improves fatigue strength. However, powder storage needs to be strictly moisture-proof: after 3 days in a 90°C/95%RH environment, the oxygen content surges to 450 ppm, resulting in the appearance of primary particle boundaries (PPBs) defects after hot isostatic pressing (HIP), which triggers brittle fracture.

Near-net forming and additive manufacturing: LPBF technology can directly manufacture turbine blades with internal cooling channels, reducing material waste and increasing design freedom. For example, GH4169 (IN718) achieves 99% density through LPBF, but the process parameters need to be optimized to suppress pores and residual stress. When hot isostatic pressing (HIP) is used to form turbine disks, high oxygen content will reduce the hot processing window, and the γ' phase size needs to be regulated by slow cooling and heat treatment to balance strength and plasticity.

Technological Innovation of Powder Metallurgy Process

Powder making technology: Argon atomization (AA) and PREP are mainstream processes. The AA method is low-cost but easy to produce satellite powder; PREP powder has high sphericity and low oxygen content (<120 ppm), which is more suitable for high-performance components. The master alloy method (such as MA35Ni) combined with injection molding can produce complex small parts at low cost, with a tensile strength of 1047 MPa.

Defect suppression and post-processing: HIP+forging process can eliminate PPBs defects. FGH98 alloy controls the solid solution cooling rate to make the γ' phase precipitate uniformly, and the fatigue crack growth resistance is increased by 30%. For the damage repair of high Al+Ti alloys (such as IN738), the "sandwich" structure welding layer and powder metallurgy repair method (C-PM) are used. Ni10-B activated powder can achieve crack-free connection at 1150°C.

Characteristics and Application Scenarios of Typical Alloy Powders

Inconel 625 (In625) powder: In625 exhibits excellent fatigue resistance, creep resistance and corrosion resistance in environments below 800°C, and is suitable for high-temperature bearing components of engines. Its composition is: Ni (matrix), Cr (20–23%), Mo (8–10%), Nb (3.15–4.15%), and high-temperature stability is achieved through solid solution strengthening.

In traditional processing, high hardness and low thermal conductivity lead to poor processability, while laser powder bed fusion (LPBF) technology can manufacture complex geometric structures: rapid cooling inhibits grain coarsening and improves strength; optimized scanning strategies (such as interlayer rotation) reduce residual stress, and the tensile strength can reach 1155.6 MPa. Inconel 625 powder can be used in engine bearings, heat exchangers, etc.

Hastelloy X (HX) powder: Hastelloy X (HX) powder still maintains good ductility at 1200°C, which is better than In718/In625; Hastelloy X (HX) powder has resistance to stress corrosion cracking (key requirement for petrochemical equipment) and excellent oxidation resistance (gas turbine combustion chamber); molybdenum enhances high temperature strength and weldability.

Hastelloy X (HX) powder can be used for combustion zone components such as gas turbine transition section, flame stabilizer, tail nozzle, etc., especially suitable for high temperature corrosion environment.

Inconel 718 (In718) powder: Inconel 718 (In718) powder is dominated by γ'' phase (Ni₃Nb), providing high strength in medium and high temperature environment of 650–750°C. Rapid solidification forms fine grain structure in additive manufacturing (LPBF), but is accompanied by residual stress and Laves phase segregation.

Inconel 718 (In718) powder can precipitate nano γ'/γ" phase by solution annealing and two-stage aging, so that the strength matches the forging level; the untreated sample has a high high temperature creep rate, and the hardness at 650°C is significantly improved after heat treatment.

Inconel 718 (In718) powder is used for turbine disks, engine housings, fasteners, etc.

Nickel-chromium-based composite powder: Nickel-chromium-based composite powder is added with TiC/WC ceramic particles to form a metal-based composite material, which improves wear resistance by more than 50% and enhances thermal stability (experimentally verified in WC/HX composite materials); LPBF is used to regulate the distribution of enhanced phases to avoid microscopic defects.

Nickel-chromium-based composite powder is used for parts in high wear/erosion environments, such as turbine blade protective coatings.