Microstructure and Mechanical Properties of TiB/TiC Particle Modified Al-Mg-Si Alloys Fabricated by Wire-Arc Additive Manufacturing.

TiB and TiC particles were separately introduced to modify the Al-Mg-Si alloy fabricated by wire-arc additive manufacturing (WAAM) to solve the problem of hot cracking. The results showed that modification of the Al-Mg-Si alloy with TiB or TiC particles completely suppressed the hot cracks found in commercial Al-Mg-Si alloys fabricated by WAAM due to the transformation from columnar grains to fine equiaxed grains with a mean diameter of approximately 10 μm. The ultimate strength and yield strength of the as-deposited Al-Mg-Si/TiB (AD-TB) and Al-Mg-Si/TiC (AD-TC) alloys were similar, but the elongation of the latter one was higher due to its low porosity. The ultimate strength (353.7 ± 5.0 MPa) and yield strength (309.7 ± 1.9 MPa) of the heat-treated Al-Mg-Si/TiC (HT-TC) alloy was significantly higher than those (300.8 ± 2.7 MPa and 256.2 ± 2.8 MPa, respectively) of the heat-treated Al-Mg-Si/TiB (HT-TB) alloy. The fatigue resistance of the HT-TC was better than that of the HT-TB due to less porosity and a more uniform distribution of TiC particles in the HT-TC alloy.