A nickel-based superalloy was fabricated by laser additive manufacture and conventional casting method respectively. The microstructure of both alloys after heat treatment was observed by SEM. The tensile properties of specimens were tested from room temperature to 1 000 ℃

and the fracture characteristics were observed. The results indicate that the microstructure of the specimens fabricated by laser additive manufacture is heterogeneous

where the γ′ precipitations at dendrite arms are regular

however

the precipitations in the interdendrite regions are coarse and irregular. The tensile strength and elongation are slightly lower than those of the alloy fabricated by conventional casting method. At room temperature

the fracture mechanisms of both specimens are dominated by cleavage fracture. In the case of medium temperatures

both are dominated by shear fracture

while those at high temperature are dominated by micropore aggregation fracture. Therefore

the heat treatment process should be optimized to improve the microstructure uniformity

strength and plasticity.