Study on energy absorption enhancement mechanism of porous TC4 titanium alloy compared with porous titanium under static and impact loads

In this study, porous titanium and porous TC4 (Ti–6Al–4V) titanium alloy with a porosity of 55 ± 2 % were fabricated using the magnesium particle space holder-distillation-sintering process. Through performance tests and microstructural characterization, the differences and underlying mechanisms of their quasi-static and impact compression properties were investigated. Under quasi-static compression, the energy absorption density (65.01 ± 11.70 MJ/m 3 ) and energy absorption efficiency (75.58 ± 2.95 %) of porous TC4 were significantly superior to those of porous titanium (28.77 ± 3.16 MJ/m 3 and 59.98 ± 5.05 %, respectively), corresponding to 2.26 times higher in energy absorption density and 1.26 times higher in energy absorption efficiency. Macroscopically, porous TC4 exhibited a prolonged stress plateau owing to sufficient deformation and slow crack propagation. Microscopically, Al and V pinned dislocations, inhibited dynamic recovery, and promoted the formation of stable low-angle grain boundary (LAGB) networks, thereby avoiding strain localization. Under impact compression tested via SHPB over strain rates of 1282–4290 s −1 , porous TC4 demonstrated a more pronounced strain-rate strengthening effect. This is attributed to the elevation of the Peierls–Nabarro stress and the introduction of the solute drag effect by Al and V, which rendered dislocation motion highly dependent on strain rate. The study elucidates the regulatory role of alloying elements, quantifies the contribution of micro-factors to strain-rate strengthening, identifies Al and V as the core elements for performance enhancement, and provides key theoretical and technical foundations for the optimization of porous metallic materials.