Abstract: W-3.5Nb alloy was formed by selective electron beam melting (SEBM). Defect and microstructure of W-3.5Nb alloys that were fabricated by different process of low-speed scanning, high-speed scanning and remelting were analyzed. The results show that: lack of fusion and micro-cracks are main defects in SEBMed W-3.5Nb alloys. Low-speed scanning can effectively reduce the content of defects. Lack of fusion defects are caused by the spheroidization and the disturbance of the molten pool. The micro-cracks are mainly caused by shrinkage between dendrites during the solidification process. Due to the different solidification processes of the molten pool at different scanning speeds, W-3.5Nb showed different microstructural. Epitaxial growth is not obvious due to the inadequate fusion under high-speed scanning, leading fine microstructure and not obvious preferred orientation. At low scanning speed, thick columnar crystal structure with (001) preferred orientation along the forming direction is formed by epitaxial growth. At the remelting condition, the columnar crystal and the preferred orientation of the grain are weakened.
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2021, Vol. 35 
