Thermal expansion and temperature-dependent Young’s modulus of Invar fabricated via laser powder-bed fusion

Invar alloys possess the peculiarity of dimensional invariance, which is of importance for high precision applications, such as measurement instruments. As ductile face-centered cubic (fcc) material, it is adequately weldable and is nowadays readily available as powder feed stock for additive manufacturing processes. Single-phase fcc alloys are known to often be highly textured, when fabricated via laser powder-bed fusion. Within this study, the thermal expansion behavior was analyzed via true differential dilatometry and the directional Young’s moduli were determined via impulse excitation technique in the temperature range up to 850 °C. The coefficient of thermal expansion was found to be nearly independent of the analyzed orientations. However, Young’s moduli differed by 20 GPa, with the highest stiffness obtained for specimens orientated parallel to the x-axis of the machines’ coordinate system.