Promoting strengthening and grain refinement of aluminum alloy during wire and arc additive manufacturing by adding TiB2 particles

The influence of submicron-sized TiB2 particles on the microstructure and properties of deposited 2319 Al has been investigated. The Al matrix demonstrated a small undercooling (ΔTfg≈1.12 K « ΔTAl-Cu≈13 K) satisfying its own free growth because of the addition of TiB2 particles. This promoted the nucleation and growth of an extremely large number of grains and hindered the migration of grain boundaries, thereby refining the grains from 96.5 to 47.42 μm. The texture features reduced with the decrease of the pole density of Al d from 1.997 to 1.417, and the maximum pole density value of CuAl2 decreased from 8.953 to 3.597. The plentiful θ′ phases precipitated near the grain boundary which restrained the formation of reticular eutectic phase, with a semi-coherent interface with the Al matrix, (112)CuAl2//(111)Al. Resulted in excellent precipitation strengthening of being the best strengthening effect by θ′ phases, the strength of the deposited sample was increased by 30 %, reaching 304 MPa.