Effect of HIP Conditions on the Microstructure of a Near γ-TiAl+W Powder Alloy

Abstract
A Ti-48AI-2W (at%) near γ-TiAl powder alloy was hot isostatically pressed at 207 MPa and 1100°C to 1430°C, for 10 minutes to 4 hours. Densities of >99.9% were achieved in the HIP consolidated specimens. Four types of microstructure containing γ-TiAl, α2-Ti3Al and W-rich β 0 phases were produced: equiaxed, duplex, nearly lamellar and fully lamellar. HIP treatments for a short duration at≥1400°C improved the uniformity of the microstructure. A longer HIP time at 1400–1430°C was required to achieve compositional homogeneity. The HIP pressure had a significant effect on the microstructural changes, whereas the W homogenization was not as sensitive to the pressure.