Vacuum Atomization.pdf

Gas atomization (GA) techniques, including open air, inert gas blanket, and vacuum conditions, impact the level of gaseous impurities in metal powders. Vacuum atomized powder achieves the lowest levels of oxygen and nitrogen, crucial for controlling mechanical properties in applications like aerospace components.

Nickel-based superalloys, such as Inconel 718, require tightly controlled mechanical properties, including resistance to thermal creep deformation, corrosion, and oxidation. The quality of metal powder degrades with repeated use, affecting the performance of built components. Oxygen levels above 200 ppm can degrade mechanical properties like elongation and ultimate tensile strength (UTS).

Studies show that oxygen content significantly affects the mechanical properties of HIPed and heat-treated samples. Table 2 demonstrates the effect of oxygen content on rupture life, with higher oxygen levels resulting in inferior mechanical properties. Table 3 compares typical oxygen and nitrogen content in nickel-based superalloys from different production methodologies, highlighting the benefits of vacuum atomization.

Key findings include:
- Vacuum atomization produces powders with the lowest oxygen and nitrogen levels.
- Oxygen levels above 200 ppm can degrade mechanical properties.
- Inert gas blanket techniques can improve powder quality but may not meet critical application specifications.
- Open air techniques generate powders with relatively high gaseous impurities, resulting in inferior mechanical properties.

To meet critical application specifications, understanding the impact of melting techniques on impurity levels is crucial. Vacuum atomization may be the preferred technique for applications requiring low oxygen and nitrogen levels.