Microstructural evolution and strengthening mechanisms of Inconel 718 alloy with different W addition fabricated by laser cladding

Abstract

In this study, Inconel 718 alloys with various W additions (0, 6, 12, and 18 wt%) were fabricated by laser cladding. The influences of W addition on the microstructure and mechanical properties of the as-deposited Inconel 718 alloy were studied. The results show that with the rise of W addition, the fraction of Laves phase, the low-angle grain boundaries (LAGBs), and the dislocation density monotonically increase, whereas the grain size and interdendritic region of Inconel 718 alloy decrease, and the alloy with no interdendritic region can be obtained at a W addition of 18 wt%. Additionally, Fe2W phase is observed above the striped Laves phase in Inconel 718-18 W alloy. As the introduction of W increases from 0 to 18 wt%, the microhardness of alloys enhances from 273.1 ± 19.4 HV to 380.2 ± 12.6 HV. Moreover, the ultimate tensile strength (UTS) and yield strength tensile (YS) of the Inconel 718 are constantly enhanced by increasing W addition, while the elongation (El) decreases. The as-deposited alloy sample with 12 wt% W addition exhibits excellent comprehensive properties compared to the other samples. The YS, UTS, and El of Inconel 718-12 W alloy are 749.96 ± 16.25 MPa, 1106.71 ± 30.39 MPa, and 18.61 ± 1.47%, respectively. The excellent comprehensive mechanical properties of the Inconel 718-12 W alloy is mainly attributed to dislocation strengthening and solid solution strengthening. The present study provides a new way to achieve as-deposited Inconel 718 alloy with excellent synthetical mechanical properties.