Enhanced mechanical properties of Co-containing W-Ni3Al alloy by trace Y2O3 addition

Abstract

Although W-Ni₃Al alloys have many promising applications in the civil and military fields, their further development requires better mechanical properties. In this study, based on our reported W-Ni₃Al-Co alloy, its mechanical properties were greatly enhanced via adding trace Y₂O₃. Among them, the 0.1 wt.% Y₂O₃ added alloys exhibited excellent comprehensive properties, whose relative density, hardness, bending strength, and tungsten grain size were 99.86%, 71.2±0.22 HRA, 1733.32±27.32 MPa, and 3.57±1.15 μm, respectively. By analyzing the relationship between microstructures and mechanical properties of sintered W-8.9Ni₃Al-1Co-0.1Y₂O₃ alloy, its outstanding mechanical properties were mainly attributed to the following factors: Firstly, the binder phase and W phase were solid-solution-strengthened by forming (Ni,Co)₃(Al,W) and (W,Co,Al) solid solutions; Secondly, the added Y₂O₃ and formed Al₂O₃ particles contributed to produce the dispersion strengthening and fine grain strengthening; Thirdly, the interfaces between Y₂O₃ and Al₂O₃ were strengthened by the formed Y₄Al₂O₉ phase. The above factors played an important role in improving the mechanical properties of containing-Co W-Ni₃Al alloy, especially the substantial increase in bending strength.