Abstract:Owing to good welding properties and low cost, carbon steel is often used to produce capsules to consolidate TiAl based alloy powders via hot isostatic pressing (HIP). Under high temperature and pressure, the density of TiAl pre-alloyed powders is reduced due to the diffusion of atoms and the capsule fails, forming brittle intermetallics. In order to ensure reliability of the carbon steel capsule, Al2O3-ZrO2 (A-Z) layers was added to the inside wall of the 20# carbon steel capsule via thermal spraying. In the HIP experiment, the capsule with A-Z layers was used to consolidate Ti-46Al-2Cr-2Nb-(W, B) pre-alloyed powders at 1523K and 130 MPa for 2.5 hours, and then treated via HIP at 1603K and 130 MPa for 0.5 hours. To compare, the 20# carbon steel without A-Z layers was formed via processing of Ti-46Al-2Cr-2Nb-(W,B) pre-alloyed powders at 1523K and 130 MPa for 3 hours. The as-formed Hipped capsules were observed under SEM and EDS to evaluate the effects of A-Z layers. The test results reveal that the formation of brittle intermetallics was prevented upon addition of A-Z layers. During HIP, iron atoms of 20# carbon steel capsule could not meet titanium and aluminum atoms in the TiAl based alloy powders by diffusion; hence, the reliability of 20# carbon steel capsules was achieved. In addition, the compactly processed capsule of TiAl based alloy with A-Z layers was fully consolidated and exhibited a fine, nearly full lamellar microstructure. The Tensile strength and elongation of the compact at room temperature surpassed 590 MPa and 2.0% respectively.