Laser metal deposition of thin-walled parts of Al0.8CrFe2Ni2 high-entropy alloy: Process window, microstructure, wear resistance and mechanical anisotropy

Abstract

In this paper, an exponential regression model is employed to analyze the sensitivity of the geometrical characteristics of single track, building efficiency and powder efficiency to the process parameters for the Al0.8CrFe2Ni2 high entropy alloy (HEA) fabricated by laser metal deposition (LMD). Based on the exponential regression model and sensitivity analysis, an effective process window is obtained to deposit a multilayer thin-walled structure. The Al0.8CrFe2Ni2 HEA consists of the (Fe, Cr, Ni)-rich faced centered cubic (FCC) phase and (Al, Ni)-rich B2 phase. An anisotropic mechanical property along the building direction and scanning direction is discovered due to the different strengthening mechanisms and fracture modes. Dislocation strengthening dominates in the building direction, while the high yield strength in the scanning direction is the result of dislocation, grain boundaries and precipitation strengthening. Compared to 400 °C, the Al0.8CrFe2Ni2 HEA has a lower wear rate at 25 °C owing to the self-lubricating protection provided by the completed oxide glaze layer. The findings provide guidelines for improving the anisotropic mechanical properties of thin-walled parts of LMD-deposited HEAs.