Abstract
? 2022 Elsevier B.V.W-based composites with the different immiscible second phases (Cu and Cu10Sn) were prepared by laser powder bed fusion (LPBF). The immiscible W phase and Cu/α-Cu phases were prone to separate during LPBF. The melted W phase could easily fuse together and form W matrix, and Cu or α-Cu phase distributed within the gaps among W phase. Cu or α-Cu phase can provide a gradient cooling way for the solidification of W phase through the transformation of ‘solid-liquid-gas’ during LPBF. The evaporation of Cu or Sn accelerated the heat dissipation, which caused the grain refinement of W. Higher thermal conductivity of Cu than α-Cu leads to the relative finer grain size of W phase in W-Cu composite. The heat conduction direction between W phase and Cu/α-Cu also affected the grain morphology. Heat continued transferred from W to Cu/α-Cu induced the columnar grain growth of W, the interlacing distribution of W and Cu/α-Cu made the growth of W columnar grains radiate out from the center Cu/α-Cu phase. Remarkable, cracks were severely restrained in W phase simultaneously although W phase melted completely. This is not only related to improvement of strength and ductility of W caused by grain refinement, but also because of the interlacing distribution of W and Cu/α-Cu phases, which could effectively reduce the stress degree in W phase during LBPF.
NSTL
Elsevier