PSI - Issue 50

N.B. Pugacheva et al. / Procedia Structural Integrity 50 (2023) 251–256 N.B. Pugacheva et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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The fracture surface relief of the specimens after transverse bending testing has a dimpled structure corresponding to ductile failure with a high work of fracture (Fig. 5). The B 4 C particles crack during testing. At the boundary with the matrix, microvoids in the form of exfoliations appear around them, which can be sources for microcrack growth under external mechanical loading. The fine TiC and TiB 2 particles are firmly bonded to the matrix, and they are not sources for microcrack nucleation.

Fig 5. The fracture surface morphology after transverse bending tests.

Fig 6. X-ray element distribution maps of the composite fracture surface after transverse bending tests (the site is shown in Fig. 5).

The comparison of the X-ray element distribution maps on the fracture surface with the results of fractographic analysis demonstrates that the Cu+TiB 2 +TiC areas are plastically deformed to a lesser extent. This corresponds to the indentation results (Fig. 4). As a rule, the areas of TiB 2 clusters, marked by 2 in Fig. 3, are fractured by cleavage (marked by arrows in Fig. 5). The TiB 2 particles appear near the B 4 C particles (Fig. 6), and this makes the plastic deformation of the matrix difficult. Therefore, near the B 4 C particles there appear microvoids, which are the sources of microcracks (Fig. 5). Nevertheless, the studied composite demonstrated high strength in transverse bending testing, namely R bm 30 = 820 MPa.