PSI - Issue 59

Lyudmyla Bodrova et al. / Procedia Structural Integrity 59 (2024) 731–738 L. Bodrova et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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along the boundaries of carbide grains and along the boundaries of aggregates ranging in size from 5 to 50 µm. No signs of transcrystalline fracture were found. As it can be seen from Fig. 3, even a low content of nano-WC changed the fracture macrostructure and the fracture mechanism, which is testified by an increase in mechanical properties, fracture toughness in particular.

Fig. 2. Thermal shock resistance of TiC – 5VC-5NbC – 5WC – yNi-Cr (a), TiC – 5NbC – 5WC – y nano Ni- Cr (b) alloys, where у = 7,5; 13,5; 18 wt. % Ni/nano Ni.

The study of the relationship between microrelief of the fracture and structural elements testified that beside microrelief elements, which specify brittle fractures, such as terraces and river patterns, separate characteristic areas of microplastic failure are observed: pits and tongues (Fig. 3d). Equilibrium and elongated pits are the main elements of such microrelief.

Fig. 3. Fracture macrofractographs of the alloy TiC – VC – NbC – 5WC – NiCr (a.b), TiC – VC – 5 nano WC-NiCr (c, d), ΔT = 800 °C.