Designing an Additively Manufactured Ti-Al-Fe Alloy with a Wide Process Window.

Area of Science:

• Materials Science
• Additive Manufacturing
• Metallurgy

Background:

• Laser powder bed fusion (LPBF) requires specialized alloys for optimal performance.
• Developing cost-effective titanium alloys with tailored properties is crucial for advanced applications.

Purpose of the Study:

• To design and fabricate a novel, cost-effective titanium alloy (Ti-5.2Al-5Fe wt.%) for LPBF.
• To optimize the alloy for low density, high strength, and good β-phase stability.
• To investigate the influence of composition on processability and microstructure.

Main Methods:

• Alloy design and composition optimization (Ti-5.2Al-5Fe).
• Fabrication using laser powder bed fusion (LPBF).
• Characterization of microstructure, mechanical properties (tensile, hardness), and defect analysis (porosity, EBSD).

Main Results:

• Achieved low density (4.4 g/cm³), high yield strength (1052 MPa), and high hardness (>400 HV).
• Demonstrated excellent formability with high densification (porosity ≤ 2%) across a wide energy density range.
• Identified α and β phases in the as-built microstructure, with α-phase content varying with energy density.
• Observed high tensile strength (>1290 MPa) but limited ductility (<2.6%).
• EBSD analysis revealed micro-residual stress in the α-phase as the cause of low ductility.

Conclusions:

• The novel Ti-5.2Al-5Fe alloy shows promise for LPBF applications due to its favorable properties and wide process window.
• Understanding the role of residual stress in the α-phase is key to improving ductility in future LPBF titanium alloys.
• This study provides insights into alloy design and microstructural mechanisms for LPBF-dedicated titanium alloys.