Next Materials (Jan 2025)
Study of microstructure, phase and mechanical properties of a novel titanium aluminide-based alloy fabricated by direct energy deposition
Abstract
Titanium aluminide (TiAl) alloy is deemed to possess desirable properties but exhibits significant drawbacks such as poor fracture toughness, wear and ductility that impedes its structural application and limit workability and production. Hence, it is crucial to accomplish a sufficient stability in relation to strength and ductility without losing other attractive material properties of the TiAl alloy. Therefore, this work is aimed at studying a novel TiAl-based alloy synthesized using direct energy deposition (DED) technique. The alloy was developed through in-situ alloying with Al, Si, Ti, Mo and V elemental powders to fabricate quintenary alloy of Ti-Al-Si-Mo-V. From the results obtained, it was observed that the microstructural and phase analysis of the Ti-Al-Si-Mo-V alloys exhibited varying amount of β0 and ζ-Ti5Si3 phases along the grain interfaces reliant on the amount of Mo and V present with the formation of fully lamellar (FL) and duplex phase (DP) microstructures for 1400 °C and 1200 °C heat treatment temperatures, respectively. The Ti-Al-Si-Mo-V alloy ultimate tensile strength (UTS) was about 6.6–49.3 % greater than Ti-48Al-2 Nb-2Cr (GE-4822) alloy; while the yield strength (YS) was up to 34 % greater than GE alloy based on the nanoindentation results. Consequently, the Ti-Al-Si-Mo-V alloy would perform very well as material for aero-engines parts. The simulation result shows that cracking could be avoided by increasing the processing temperature. It was inferred that the processing temperature does not affect the maximum stress experienced by the TiAl alloy but the minimum stress level changes with processing temperatures.
