Achieving high strength in BNNSs reinforced W-Re alloys via heterogeneous particles with coherent interface

The enhancement of mechanical properties is crucial for the development of tungsten (W) alloys as structural materials in critical applications. In this work, boron nitride nanosheets (BNNSs) reinforced W-5 wt% Re alloy with high strength was fabricated by hot-pressing sintering followed by hot rolling. Most of BNNSs were well-retained and WN nanolayer was formed around BNNSs via in-situ reaction partially, resulting in improved interfacial adhesion. In addition, the in-situ nanoscale WB particles uniformly distributed within W grains, exhibiting coherent interfaces with the matrix. The microhardness of BNNSs reinforced W-5 wt% Re alloy is 532.4 HV_0.3. At 200 °C, the ultimate tensile strength (UTS) of BNNSs reinforced W-5 wt% Re alloy is 1277 MPa (53.9 % higher than W-5 wt% Re alloy), indicating markedly higher strength compared with those reported in particles dispersion-strengthened W alloys, while the total elongation (TE) remains a value of 8.9 %, which is 85.4 % higher than that of W-5 wt% Re alloy. Microstructural characterization and quantitative analysis reveal that the enhanced strength is attributed to synergistic effect from heterogeneous particle strengthening (intergranular submicron BNNSs and intragranular nanoscale WB), coherent strengthening from in-situ formed interfaces and fine-grain strengthening.