Fabrication of large cross-section Ti–6Al–4V alloy using EBS-modified POM-based feedstock

Plastic shaping offers a viable method for the formation of complex structures. However, current research primarily focuses on small and medium-sized components, with limited exploration on the forming, debinding, and sintering of complex components with large cross-section. In this study, by mixing spherical Ti–6Al–4V powder with polyformaldehyde (POM)-based binder, three different feedstocks were prepared, varying in powder loadings and modified with ethylene bis-stearamide (EBS) modification. The feedstock properties were studied, and cylindrical samples with a cross-section thickness of 30 mm were fabricated via rheological press molding (RPM) to investigate their debinding and sintering behavior. The results showed that the increase in powder loading increased the feedstock viscosity but reduced the impurity content (C, O). EBS reduced the contact angle between the powder and POM, and increased the viscosity and sensitivity to shear rate changes. Catalytic debinding of the samples was completed in 2 h. After sintering, EBS-modified Ti–6Al–4V h showed uniform sintering shrinkage, microstructure, the highest relative density of 97.10%, a yield strength of 701 ± 5 MPa, and an ultimate tensile strength of 746 ± 13 MPa.