Balancing mechanical properties in tungsten-alumina oxide alloys via coherent/semi-coherent interfaces

Abstract

The trade-off between strength and toughness has always presented a challenging issue in the development of high-performance metallic structural materials. Introducing hard, non-deforming particles in W metal can effectively enhance strength; however, the severe stress concentration at heterogeneous phasal interfaces often cause strain incompatibility, thereby deteriorating toughness. Here, we constructed robust coherent/semi-coherent W/Al₂O₃ interfaces to achieve a balance between strength and deformability of W/Al₂O₃ materials. Under 15 % compression deformation, our material exhibits a strength exceeding 2200 MPa and an impressive hardness of HV_0.2 = 637.4, among the best sintered dispersion-strengthened W alloys reported. The strong coherent/semi-coherent interfaces between W and Al₂O₃, as confirmed by TEM observations and DFT calculations, effectively hinder crack propagation along the phase boundaries, and instead, the cracks tear the Al₂O₃ particles dispersed at the W grain boundaries, considered responsible for the high ductility. This study provides new insights into the synergistic strengthening of dispersion-strengthened W alloys.