Metal Injection Molding for Net Shape Manufacturing of Nickel and Titanium Alloy Parts

Abstract

The application of metal injection molding for producing complex-shaped components from the Inconel 718 nickel alloy and titanium alloys (Ti–6Al–4V, Ti–3Al–2V) was studied. The research used both spherical doped powders and mixtures of irregular powder particles. The objective was to solve the following primary challenges: prevent the failure of parts during organic binder removal prior to sintering and impart the required geometry to the final sintered components, along with a lowporous structure. Various engineering strategies were systematically evaluated, including the use of support structures of different designs for sintering, specialized substrates with antiadhesive coatings, horizontal or vertical orientation of parts, and incorporation of reinforcing ribs directly into the parts. The experimental results showed that external support systems were ineffective in preventing damage caused by shrinkage, which led to cracking and failure of the parts. Moreover, adhesion between the parts and support structures caused defects, resulting in shape distortion, reduced product quality, and surface contamination. The most optimal solution was to integrate reinforcing ribs directly into the parts. These ribs could be easily removed in post-sintering finishing operations and eliminated the need for external supports. This approach enabled crack-free sintering without distortion of the final part geometry. Powder coatings based on yttrium oxide (Y₂O₃) provided effective antiadhesive properties. Microstructural analysis of the sintered materials confirmed the production of dense, homogeneous alloys with average grain sizes of 30–60 μm (Inconel 718) and 100–150 μm (titanium alloys). The developed methodology allowed the successful fabrication of turbine blade prototypes with the required surface quality.