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 LPBF-processed 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.