Sinterability and microstructure evolution of powder metallurgy processed titanium aluminides

Abstract

The objective of this study was to assess the effect of different aluminium additions in microstructure evolution and hardness of powder metallurgy processed titanium aluminides. Alloys with aluminium contents of 10, 20, 30, 40 and 45 at.-% were prepared using mixtures of elemental powders that were cold uniaxially pressed. Sintering was conducted at 1300 and 1400°C for 2 h under argon atmosphere. The results indicated a sharp decrease in sinterability for larger elemental aluminium additions. Furthermore, the hardness values decreased with the aluminium content due to the higher porosity. However, in alloys with higher aluminium content, despite the higher porosity, microstructural homogeneity was improved and equilibrium phases α₂-Ti₃Al and γ-TiAl could be achieved in fully lamellar Ti-40Al and Ti-45Al.