Achieving ultra-high strength-ductility synergy and strengthening mechanism of discontinuously reinforced titanium matrix composites at room/high temperature via multi-scale “non-uniform network structure” innovative design

The present work proposed a novel design concept for multi-scale “non-uniform network structures”, which led to the development of discontinuous reinforced titanium matrix composites (DRTMCs) that exhibited markedly different reinforcement morphologies, scales, and spatial distribution. Micro/nano-sized TiB and nano-sized La₂O_3p were incorporated into a Ti60 alloy matrix, and the distribution modes of the reinforcement phase were precisely designed and controlled to promote a synergistic enhancement of strength and ductility at both room and elevated temperatures. The results indicated that the room temperature ultimate tensile strength (UTS) of the (0.5 wt. % TiB₂ + 0.3 wt. % LaB₆ + 0.02 wt. % Si)/Ti60 composite reached 1544 ± 3 MPa, with the elongation (EL) of 5.8 ± 0.25 %. At 700 °C and 750 °C, the UTS were 593 MPa and 536 MPa, respectively. The structural characteristics featured fine-grained (FG) regions containing nanoscale reinforcements embedded within a coarse-grained (CG) network structure. This unique microstructural configuration of the new DRTMCs retained the inherent advantages of conventional network structures while introducing additional strengthening mechanisms such as fine-grain strengthening, dislocation strengthening, and strain hardening. Consequently, multiple strengthening mechanisms acted synergistically, imparting exceptional mechanical performance to the DRTMCs at both ambient and elevated temperatures. Notably, this study provided valuable strategies and mechanistic insights for the further development and engineering application of high‑temperature DRTMCs.