Implementation focused on bridging the gap between laboratory processing (high-pressure torsion, HPT) and industrially scalable consolidation (SPS/hot pressing). TOUGHIT relied on HPT pressures of ~10 GPa, which are only achievable for sub-centimeter samples. In contrast, SPS and hot pressing operate at ~200 MPa for larger geometries. Early trials showed that processing pure commercial W nanopowders under these lower industrial pressures resulted in rapid grain growth and grain sizes of several micrometers, rather than the desired nanostructure. It became evident that adjusting SPS parameters alone is insufficient to arrest grain growth at these pressures, underscoring the need for microstructure control by design.
Consequently, the project prioritized a synthesis strategy that modifies grain boundary behavior and densification kinetics at the powder level. Alloying strategies for W nanopowders were investigated with two goals: (i) impede grain boundary mobility to counter coarsening, and (ii) accelerate densification, for example via nanophase separation, to reach high density quickly and at lower temperatures. While mechanical alloying can mix powders, its drawbacks, such as media wear, contamination, and irregular particle morphology, were deemed significant for industrial transferability, steering the project toward approaches that better preserve powder purity and morphology.
Process development proceeded with SPS optimization, emphasizing a data-driven workflow: systematic variation of pressure, temperature, and time; microstructural characterization (grain size distributions, pore fractions), and hardness mapping to correlate microstructure and properties while identifying gradients or surface effects. All process steps, parameters, and outcomes were electronically documented to ensure reproducibility and facilitate transfer to industrial equipment and product requirements.
These efforts culminated in identifying parameter windows that maximize densification while avoiding unnecessary grain growth, meeting the deliverable goal of achieving dense components with refined microstructures under industrially relevant constraints. Beyond technical progress, knowledge transfer and dissemination advanced through presentations and publications (one proceeding published, one manuscript under review and another one in preparation) to engage both scientific and industrial communities. The data management plan (Deliverable 2) was completed early, and no part of the action was subcontracted. Industrial collaboration remained robust, the company partner provided access to powder resources and SPS facilities and supported the alignment of process parameters with production capabilities and target product specifications throughout the project.
