Laser powder bed fusion of compositionally graded Invar36/Ni22Cr3

Functionally graded materials directly bonded with various alloys may result in high internal stress and defects at the interface due to the mutation of the component elements, thus affecting the quality of the formed specimens. Compositionally graded alloys (CGA) based on the LPBF process can achieve uniform changes in elements to reduce the occurrence of defects. The microstructure, mechanical properties and thermal expansion properties of Invar36/Ni22Cr3 CGA alloy were investigated in this paper. The sample has a high relative density, with a density of about 99.78 % on the Ni22Cr3 side. As the Ni22Cr3 content (10 wt% Invar36) increases, the single fcc γ phase transforms into the fcc γ and bccα phases. The S5 sample is particularly unique, with a smaller grain size of 11.46 (±2.23) μm, and a larger KAM value. The S1 sample has the highest elongation of about 35.0 (±0.63) % compared to other representative samples. With the change in temperature, Invar36/Ni22Cr3 CGA represents a significant change in the thermal expansion displacement curve of the sample.