Microstructure, thermal conductivity and mechanical anisotropy of DURACON 45M fabricated by laser-wire directed energy deposition

Abstract High-thermal-conductivity tool materials are critical for reducing cooling-limited cycle times in polymer processing. Microstructure, mechanical anisotropy and thermal conductivity of the Fe–Co–Ni alloy DURACON 45M fabricated by laser-wire directed energy deposition (LW-DED) are investigated. The as-built material exhibits near-full density and a direction-dependent microstructure. EBSD analysis showed a refined grain structure with grain sizes predominantly below 10 µm in the X direction, while the Z direction contained coarser grains elongated along the thermal gradient. In comparison, the wrought base material (BM) exhibited grain sizes mainly around 10 µm. Mechanical testing revealed significantly enhanced tensile strength in the build plane, whereas ductility was markedly reduced along the build direction due to the anisotropic microstructure consisting of elongated columnar grains and crystallographic texture. Despite these microstructural changes, the thermal conductivity remained high ( $$\sim$$ 68 $$\mathrm {W\,m^{-1}\,K^{-1}}$$ ). No measurable anisotropy was observed within the uncertainty of the present measurements, and the values remained comparable to those of the base material. These results demonstrate the potential of LW-DED DURACON 45M produced using the investigated processing conditions for advanced tooling applications while emphasizing build-direction anisotropy as a key design constraint.