Simultaneously improving strength and ductility of NiAl-based composites through two-scale network structures and a core-shell-like structure

Simultaneously improving strength and ductility was achieved in a novel NiAl-based composite with two-scale network structures and a core-shell-like structure prepared by hot isostatic pressing (HIP). The HfO 2 formed in situ along the original powder boundaries and HfRe 2 transformed in situ along the grain boundaries within the original powders constituted the first-scale and second-scale network structures respectively. The nanoscale Hf 21 Re 25 precipitation zone around the grain boundaries constituted the shell structure, and the region at the center of the grains constituted the core structure. The composite exhibited excellent comprehensive mechanical properties due to the multi-scale structures. The room-temperature ultimate compression deformation up to 0.471 could be attributed to the significant fine-grain effect due to the network structures, the hindering effect of the network structures on crack extension, and the shell structure preventing excessive concentration of dislocations at grain boundaries. The high level of ultimate compressive strength (207 MPa) at 1050 °C was mainly due to the hindrance of dislocations by the particles in the network structures and shell structure. The multi-scale structural design broke through the strength-ductility trade-off dilemma and provided a new idea for the structural design of composites.