Achieving fine-grain tungsten heavy alloys by selecting a high entropy alloy matrix with low W grain growth rate

It is difficult to prepare fine-grain tungsten heavy alloys (WHAs), e.g. W-NiFe, by liquid phase sintering (LPS) mainly because of high solubility of W in the NiFe matrix. To obtain fine W grains, this work proposes to reduce W grain growth rate by selecting a high entropy alloy (HEA) with low diffusivity and solubility of W as the matrix of WHA. The results show that the LPS W-HEA has a fine W grain size of ~9.7 μm, which is about a third of the value in the conventional LPS W-NiFe. The fine W grains in the as-sintering W-HEA contribute to high yield strength and ultimate tensile strength of 840.8 MPa and 1267.3 MPa, respectively. These results suggest a new pathway for obtaining a fine-grain WHA by tailoring the matrix composition.