Microstructure and mechanical properties of Al-Mg-Si/Al-Mg-Sc laminated composite fabricated by wire-arc directed energy deposition

A crack-free Al-Mg-Si/Al-Mg-Sc laminated composite was successfully produced by wire-arc directed energy deposition (WADED) using Al-Mg-Si and Al-Mg-Sc filler wires alternately. The microstructure, mechanical properties and anisotropy of the laminated composite were investigated and the post heat treatment is optimized. The results show that the microstructure is consisted of a heterogeneous structure of "coarse columnar grains (Al-Mg-Si layer) - fine columnar/equiaxed grains (interlayer zone)- equiaxed grains (Al-Mg-Sc layer)". The change of Mg content and the presence of continuous primary Mg2Si phase along the grain boundaries suppressed hot cracking in the Al-Mg-Si layers of the Al-Mg-Si/Al-Mg-Sc laminated composite. The mechanical properties of the laminated composite did not show anisotropy. After direct aging at 300 degrees C for 1.5 h, the tensile strength and yield strength of the composite along building direction are increased by 20 % and 50 %, respectively. The results are expected to provide a basis to design crack-free and heterostructured alloys using the WADED technology.