Article ID: TETSU-2024-066
Super invar alloy, Fe–32%Ni–5%Co, is widely utilized in precision instruments due to its remarkably low thermal expansion coefficient. Additive manufacturing holds promise for fabricating complex-shaped components with this alloy. This study investigated the phase stability and thermal expansion properties of super invar alloy fabricated via Laser Powder Bed Fusion (AM sample), comparing them to those of conventionally cast material (Re-melt sample). Microstructural analysis indicates that the AM sample has a more stable austenitic structure, attributed to minimal micro-segregation. Furthermore, it was observed that the thermal expansion coefficient decreases consistently with higher cooling rates within the temperature range of 400-300 K. As a result, AM sample exhibits lower expansion coefficient and it maintains at lower temperatures.
