A novel Al-Cr-Sc-Zr alloy additively manufactured via laser directed energy deposition: Microstructure, phase analysis and mechanical properties

A novel Al-Cr-Sc-Zr alloy was designed for laser directed energy deposition (DED) considering its DED processability and high-temperature mechanical properties. Bulk samples with high-density (relative density over 99.8%) were successfully prepared, consisting of three main phases of a refined alpha-Al, rosette-shaped Al45Cr7 and L12-Al3(Sc, Zr). It was observed that Al45Cr7 phase exhibited preferential growth directions along [112], [001], [111], and [111]. Here, the monoclinic Al45Cr7 phase with an internal icosahedral-quasicrystal structure was characterized and analyzed, revealing significant orientation relationships: i5// [101] Al45Cr7, i2// [010] Al45Cr7 and i3// [112] Al45Cr7. Due to the exceptional hardness and thermal stability of the quasicrystal phase, a tensile strength of 304.8 MPa was obtained at optimized laser power 1600 W and scanning speed 600 mm/min. Additionally, the developed alloy exhibited better thermal stability, with a tensile strength of 189.43 MPa at 200 degrees C and a room temperature strength retention of 62.14%.

Automated summary

A novel Al-Cr-Sc-Zr alloy with high-density bulk samples and a refined structure consisting of three main phases was designed and analyzed for laser directed energy deposition (DED). The Al45Cr7 phase exhibited preferential growth directions and internal icosahedral-quasicrystal structure, leading to exceptional hardness and thermal stability. At optimized laser power and scanning speed, the alloy demonstrated high tensile strength and improved thermal stability.