Microstructure and strengthening mechanism of grain boundary strengthened W-ZrB2 alloy

Using the unique properties of ultra-high temperature ceramic material, a new kind W-ZrB2 alloy was prepared. Compared with pure tungsten (PW), the mechanical properties of W-ZrB2 alloy were obviously improved. In particular, the sintered alloy showed complete transgranular fracture morphology, and the originally weak grain boundaries of tungsten were greatly strengthened. From macroscopic fracture to microscopic crystal structure, the strengthening mechanism of ZrB2 in tungsten matrix was studied by means of transmission electron microscope and energy spectrum analysis. The decomposition of ZrB2 and the structure of its decomposition products had been confirmed. The formation of the second phases of various crystal structures and the distribution of B element on the grain boundaries were the key factors to strengthening mechanism.