Microstructure, cracking behavior and mechanical properties of René 104 superalloy fabricated by selective laser melting

•The maximum relative density of 99.0% was acquired in the SLM-processed René 104 superalloy.•The cellular structures on the XY plane and columnar grains on the XZ plane were identified in the SLMed René 104 alloy.•The thermal stress, HAGBs and low melting point γ-γ' eutectics played a vital role in cracking.•The columnar grains with fiber texture and the microcracks contributed to anisotropy of tensile performance. Selective laser melting (SLM) is a progressive forming technique for manufacturing complicated components, whereas the microcracks emerge in the preparation process of powder metallurgy (PM) nickel-based superalloy samples undesirably. In this study, René 104 PM nickel-based superalloy samples were prepared by SLM, and the microstructure, cracking behavior and mechanical properties of the as-printed samples were systematically investigated. The results demonstrate that the microstructure of the SLMed René 104 alloy is composed of sub-micron cellular structures on the XY plane, and columnar grains paralleled to building direction on the XZ plane, which is corresponding to the intense fiber texture. Both the solidification cracking and liquation cracking propagate along the high angle grain boundaries (HAGBs) in the SLMed René 104 samples, among which thermal stress and low melting point γ-γ′ eutectics have significant effected on cracking behavior. Additionally, the tensile performance of as-fabricated René 104 samples is obviously anisotropic, which is ascribed to the directional growth of columnar grains with fiber texture and the microcracks are perpendicular to the tensile test direction. This research provides the relationship among the microstructure, microcracks and mechanical properties for the René 104 PM nickel-based superalloy fabricated by SLM and exhibits the potential to fabricate similar alloys without cracks.