Improved compressive strength of laser powder bed fused porous tantalum by hot isostatic pressing

As structure-function integrated materials, highly interconnected porous materials have many advantages such as load bearing, light weight, and mass transfer. The advancement of additive manufacturing technology has prompted increasing scholarly attention towards the unit cell structural design and specific strength enhancement of the porous material. This study proposes an innovative high-pressure heat treatment technique for the performance optimization of the triply periodic minimal surface (TPMS) porous tantalum (Ta) components fabricated by laser powder bed fusion. The experimental results demonstrate that the hot isostatic pressing (HIP) process at 850 ℃ facilitates closure of internal micropores and enhances compressive strength without compromising the plasticity of porous Ta components. However, due to the oxygen sensitivity of Ta at high temperature, the oxidation rate of Ta samples rapidly increases with temperature. During HIP at 1350 ℃, oxygen atoms invade the Ta matrix to form Ta₂O₅, with the oxides providing stress concentration locations and crack propagation paths, leading to brittle fracture of the 1350-HIP samples. In addition, the anisotropic compressive strength of the porous Ta was further investigated in this study, revealing a greater compressive strength along the horizontal direction compared to that along the building direction.