Microstructure and mechanical properties of VNbTiSi lightweight refractory eutectic high-entropy alloy prepared by additive manufacturing
The combination of high-entropy alloys and additive manufacturing technology provides a new idea for the integrated manufacturing of complex structural components in extreme service environments.VNbTiSi lightweight refractory eutectic high-entropy alloy(REHEA)was successfully prepared by laser melt deposition(LMD)technology.The optimal laser power parameters were selected through microstructure analysis,and the compression properties of the samples were tested at room temperature and high temperature.The results show that the VNbTiSi lightweight refractory eutectic high-entropy alloy has excellent printability,and the samples prepared under the optimal process parameters have no cracks in both macro and micro aspects.At the bottom surface of the alloy and along the build direction,the interior of the molten pool and the boundary(overlap)of the molten pool exhibit different morphology.The interior of the molten pool is composed of columnar fully eutectic structure,and the eutectic cell is a relatively coarse(Nb,X)5Si3 primary silicide phase that appears at the boundary of the melt pool.Compared to the as-cast alloy structure,the laser melting deposition significantly refines the lamellar spacing of the eutectic structure.The compressive strength of the additive manufacturing alloy can not only reach 640 MPa at 1000 ℃,but also maintain a compressive strength higher than 500 MPa at 1100 ℃.The high-temperature compressive property is significantly better than that of as-cast VNbTiSi alloy.
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