Comparative assessment of microstructure and compressive behaviours of PM TiAl alloy prepared by HIP and pseudo‐HIP technology

Abstract

The present work discusses conditions of comparable microstructure and compressive behaviours of powder metallurgy (PM) Ti–46Al–(Cr,Nb,W,B) (at.‐%) alloy prepared by hot isostatic pressing (HIP) and pseudo‐HIP technology respectively. A PM route based on pseudo‐HIP of alloy powder prepared by plasma rotating electrode process was used for the rapid fabrication of high quality TiAl alloys. The pseudo‐hipped alloy shows a fine grained microstructure which is significantly finer than that of the hipped alloy consolidated under similar conditions. The pseudo‐hipped alloy exhibits more excellent compression properties than that of the hipped alloy at elevated temperatures. By using the kinetic rate equation, the stress exponent n and the apparent activation energy Q are determined and discussed respectively. The influence of microstructure on the flow behaviour during the total hot compressive deformation was studied. The role of submicrocrystalline forming and dynamic recrystallisation due to mechanical twinning and grain matrix deformation will be discussed.

Keywords:

• Titanium aluminides
• Powder metallurgy
• Pseudo‐HIP
• HIP
• Microstructure
• Compression properties

The authors would like to thank Financial Support of National High Technology Research and Development Programme (Grant No. 2008AA03A233) and National Science and Technology Planed Project of China (Grant No. 2007BAE07B05).