Fabrication of Nano-Zro2 Strengthened Wmonbtav Refractory High-Entropy Alloy by Spark Plasma Sintering

WMoNbTaV refractory high entropy alloy (RHEA) prepared by casting method has broad application prospects in high temperature materials due to stable phase structure and excellent high temperature mechanical properties. However, WMoNbTaV alloy is still facing the contradiction between strength and plasticity at room temperature, which greatly restricts its processing, forming and subsequent engineering applications. In order to solve the contradiction between strength and plasticity for as-cast WMoNbTaV alloy, the work developed WMoNbTaV with 1 mass% additions of m-ZrO 2 nano-particles (WMoNbTaV-1ZrO 2 ) by ball mixing and spark plasma sintering (SPS). The microstructure and compressive properties were researched. Results confirmed predominant presence of body-centered cubic solid-solution with m-ZrO 2 . The grain refinement of the one phase body-centered cubic alloy by presence of oxides was determined by microstructural analyses to be 31.5%. The WMoNbTaV-1ZrO 2 alloy exhibits excellent room temperature synthesized mechanical properties to overcome conflict between strength and plasticity. The Vickers hardness, yield strength, ultimate strength and fracture strain of WMoNbTaV-1ZrO 2 are 997.77 HV, 2121.8 MPa, 2461.4 MPa and 12.7% respectively, which are surprisingly increased by 15.5%, 65.2%, 62.5% and 32.3%, in comparison with that of WMoNbTaV without m-ZrO 2 , respectively. More importantly, it is increased by 90.1%, 70.3%, 93.8% and 647.1% respectively compared with the casting method. A model is presented to study the strengthening mechanism of WMoNbTaV-1ZrO 2 , and the theoretical calculation shows that the extraordinary high strength is mainly due to the inherent strength in the multi-principal element WMoNbTaV alloy and grain boundary strengthening caused by the addition of ZrO 2 particles