Selective laser melting of crack-free René 104 superalloy by Sc microalloying

Abstract

Cracking is the critical issue of “hard-to-weld” nickel-based superalloys, especially in the component fabricated by selective laser melting (SLM). In the work, the cracks of as-printed René 104 superalloy were successfully eliminated by microalloying with Sc. The formation of Al3Sc nanoparticles promoted the heterogeneous nucleation of nickel, resulting in a 74.7% reduction of grain size and a significant decrease in< 001 > texture intensity. Compared with the original René 104 alloy, the modified René 104 alloy exhibits the yield strength of 918 MPa, ultimate tensile strength of 1289 MPa and elongation of 13.9%, which are promoted by 16.8%, 40.6% and 256.4%, respectively. Significant grain refinement provides more grain boundary area, which is beneficial to alleviate the enrichment of low melting point phase forming elements (Mo, Zr and B) and the accumulation of thermal stress at grain boundary, thereby eliminating cracks. The improvement of mechanical properties is basically ascribed to the elimination of cracks, grain refinement and the formation of Al3Sc nanoparticles. These findings provide a new perspective for the research and application of “hard-to-weld” nickel-based superalloy prepared by SLM.