Additive manufacturing of W-Fe composites using laser metal deposition: Microstructure, phase transformation, and mechanical properties

摘要

A strong, ductile W-Fe functional composite interlayer is desirable for relieving the thermal stress between W and steel for applications in the nuclear industry. In this study, we fabricated high-density W-Fe composites using laser metal deposition (LMD). The influence of the composition and thermal history of the composites on their microstructural evolution and mechanical properties were investigated via single-bead and multi-layer LMD experiments. Unmelted W particles and micro-/nano-sized Fe_2W particles were observed in the as-fabricated W-Fe composites. Unique core-shell structures of W/Fe_7W_6/Fe_2W, W/Fe_2W, and Fe_7W_6/Fe_2W were also formed during the cyclic deposition process. Fine Fe_2W nanoparticles were precipitated in-situ and dispersed owing to the high solidification rate and subsequent ageing treatment resulting from the multiple thermal cycles of the LMD process. The dispersed Fe_2W nanoparticles resulted in a high compressive yield strength of over 1700 MPa with superior ductility in the as-printed W-Fe composite with 46 wt% W. This work demonstrated the feasibility of fabricating high-strength and ductile W-based composites via additive manufacturing without requiring energy-intensive and time-consuming treatments.