Laser powder bed fusion of a novel nano-modified tungsten alloy with refined microstructure and enhanced strength

Due to the thermal cycling effects of layer-by-layer deposition in laser powder bed fusion process (LPBF), the coarse columnar grains with an epitaxial growth along the building direction are prone to form in LPBFprocessed pure tungsten (W), thereby causing cracking and reduced formability. Here, the nanoparticles of Ni (1 wt%) and Fe (1 wt%) were introduced in W-matrix and a novel W-Ni-Fe alloy with nearly full densification was fabricated by LPBF. The laser-tailored microstructures transformed from coarse columnar grains to fine equiaxed grains with the addition of nano-Ni and nano-Fe. The LPBF-printed W-Ni-Fe had a considerably high compressive strength of 2638 MPa and a strain of 46%, showing about 185% and 475% improvement, respectively, as relative to the pure W under the same LPBF conditions. This work provided a feasible nano modification method to fabricate high-performance W-alloys by laser additive manufacturing.