Valorization of wood ash for sustainable in situ reinforced Ti composites with tailorable mechanical behavior manufactured via powder metallurgy

Abstract

The aim of this work is to investigate the feasibility of revalorizing commonly disposed wood ash as source to produce more sustainable in situ reinforced Ti composites. We propose a manufacturing process based on the powder metallurgy green technology and further increase the energy efficiency of the process by analyzing reactive induction sintering as the primary consolidation method. The feasibility of the proposed approach is demonstrated through the characterization of the physical, microstructural, and mechanical performance. It is found that compressibility decreases and the amount of residual porosity increases (6.0–11.7% for pressureless sintering) with the amount of wood ash used (0–0.25 wt%). However, the effective in situ creation of the reinforcement is always guaranteed by the proposed approach. Furthermore, minor adjustments of the manufacturing route can be used to maximize the amount of ash to be added for higher sustainability. The in situ reinforced Ti composites are commonly characterized by both elastic and plastic deformation and fail non-catastrophically, where for vacuum sintering ductility decreases (13.7 → 8.7%) but strength (497 → 653 MPa) and hardness (47.8 → 55.0 HRA) increase with the amount of ash used. The in situ reinforced Ti composites produced from revalorized wood ash have overall comparable or better mechanical properties in comparison to other Ti-based composites bearing a higher amount of generally more expensive reinforcements.