Effect of deposited layer thickness on the microstructure and mechanical properties of IC10 single-crystal Ni3Al-based alloy electron beam-welded joint

Abstract

IC10 single-crystal Ni3Al-based alloy has poor weldability by electron beam welding (EBW). However, a defect-free butt joint can be obtained when the Inconel 718 alloy single-crystal deposited layer is used in the IC10 alloy EBW joint as a sandwich structure with a controlled chemical composition. The experimental results show that the optimized IC10 butt joint's microstructure contains preferably orientated columnar grains with deformation twins in the intragranular region and many small NbC particles in the intergranular region. The grain size, misorientation angle, and local grain orientation in weld seam changed with the deposited layer thickness variation. The residual deposited layer was found to be the most fragile zone possessing the lowest microhardness and tensile performance in the optimized IC10 butt joint. The tensile strength of the optimized IC10 butt joints deteriorated with the increasing deposited layer thickness. The optimal design with a 0.4 mm-thick deposited layer significantly improved the EBW joint mechanical properties. In general, the deposited layer thickness strongly influenced the microstructure and mechanical properties of the optimized IC10 butt joint.