Porosity and argon concentration in gas atomized γ-TiAl powder and hot isostatically pressed compacts

Abstract The porosity, the pore size distribution and the Ar-concentration of different powder particle size fractions of Ar gas atomized γ-TiAl alloy powder is analysed. While the porosity is found to increase strongly (32–45 μm: 0.05%; 250–355 μm: 0.9% volume porosity), the Ar-concentration only varies little with increasing powder size fraction (32–45 μm: 0.5±0.15 μg g−1 Ar; 250–355 μm: 1.2±0.15 μg g−1). The reason for this different behaviour is the decrease of the Ar gas pressure inside the pores with increasing pore diameter (7 μm pore diameter: ∼0.17 MPa; 100 μm pore diameter: ∼0.03 MPa). The Ar-concentration of hot isostatically pressed γ-TiAl powder, size fraction 0–250 μm, is 0.45±0.1 μg g−1. This Ar-content can not be further reduced by choice of distinct powder particle size fractions.