1996 Volume 82 Issue 7 Pages 623-627
Behavior of inert gas entrapment into powder in the gas atomization process and its effects on the mechanical properties after consolidation have been investigated using Alloy 625 (high Ni alloy). By using supplemental gas jet impinging onto the accumulated powder in the tank bottom, the atomized powder can be rapidly cooled without any contamination. When the inert gas with no solubility in the material e.g., Ar, is used for the atomization, the powder inevitably contains Ar gas. The Ar content entrapped in the powder is largely influenced by the atomization condition, e.g., it is increased significantly by increasing the gas/metal ratio. In addition, the Ar gas content decreases with decreasing the particle size. The Ar gas concentration was about 0.5 mass-ppm in case of fine powder less than 22 microns. The Ar gas content increases with increasing the fraction of porosity in the cross section, resulting in the cavity after hot extrusion. Although certain cavities are detected in the consolidated materials, almost the same tensile and impact properties as wrought materials were obtained.
