Suppressing formation of microcracks in laser powder bed fusion manufactured AA6061 aluminum alloy by introducing mechanical alloyed Al-25at%Ti particles

Abstract

A novel approach which incorporates mechanical alloyed Al-25at%Ti particles into an AA6061 aluminum alloy powder feedstock has been used to suppress pronounced hot cracking that normally occurs in laser powder bed fusion (LPBF) manufactured AA6061 alloy. Investigation of the microstructure and tensile properties of the Ti-modified AA6061 sample fabricated by LPBF confirms the effectiveness of this approach. The suppression of microcrack formation is associated with the transition of a coarse columnar structure to fine equiaxed structure facilitated by heterogeneous nucleation of the grains on Al3Ti nanoparticles. This crack-free microstructure also results in excellent tensile properties of 252 MPa in yield strength, 361 MPa in ultimate tensile strength, and 9.7 % in elongation to fracture.