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

## TL;DR

This study designs a titanium alloy for 3D printing that maintains high strength and low porosity across a wide range of manufacturing conditions.

## Contribution

A novel Ti-5.2Al-5Fe alloy is developed with a wide process window for laser powder bed fusion.

## Key findings

- The alloy achieves high densification (porosity ≤ 2%) and hardness (>400 HV) over a wide energy density range.
- Aluminum improves melt pool wettability, while iron lowers the liquidus temperature to enhance densification.
- Low ductility (<2.6%) is attributed to micro-residual stress in the α-phase from rapid solidification.

## Abstract

To develop a cost-effective titanium alloy tailored for laser powder bed fusion (LPBF), a novel Ti-5.2Al-5Fe (wt.%) dual-phase alloy was designed and fabricated in this study. The composition was optimized for low density (4.4 g/cm3), high yield strength (1052 MPa), and suitable β-phase stability ([Mo]eq = 9.3%). The alloy demonstrated excellent formability, achieving high densification (porosity ≤ 2%) and hardness (>400 HV) over a wide volumetric energy density range (48–204 J/mm3). The Al element inhibited balling by improving melt pool wettability, while the Fe element synergistically promoted densification by lowering the liquidus temperature. The as-built microstructure comprised α and β phases, with the α-phase content increasing significantly from 25.4% to 60.8% with higher energy density. While all samples exhibited high tensile strength (>1290 MPa), ductility was limited (<2.6%). EBSD analysis identified the α-phase as the primary carrier of micro-residual stress, with a high density of “zero-solution” points, low-angle grain boundaries, and KAM values. This indicates severe stress concentration from rapid solidification and phase transformation, elucidating the fundamental reason for the low ductility. This study provides systematic insights from composition design to microscopic mechanisms for designing LPBF-dedicated titanium alloys with a wide process window.