PSI - Issue 77

Valeria Lemkova et al. / Procedia Structural Integrity 77 (2026) 279–291 Valeria Lemkova and Florian Schaefer / Structural Integrity Procedia 00 (2026) 000–000

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Fig. 5. EBSD and TKD of the Ni matrix nearby a Si 3 N 4 particle in the 50T + 5R state. The conventional EBSD su ff ers from the small grain size whereas the TKD delivers a high resolution image. In the convex region the grain size is larger compared to the concave region and the matrix.

hardened matrix. This e ff ect is prominent at room temperature since the matrix hardens fast and the particles disperse suboptimally. Furthermore, the particles do not shrink considerably during conversion. Cracking is more pronounced if mechanical contrast is high and the increase in matrix hardness is too strong. A re adjustment of the balance between grain refinement by dynamic recrystallization and grain coarsening by mechanical energy input at 300 ◦ C seems to improve the dispersion, the particle shrinking and thus, the rounding by erosion of the particles. Sabirov et al. Sabirov et al. (2005) found no clustering of Al 2 O 3 particles in an Al matrix. All clusters had been eroded during HPT. However, the mechanical contrast between the Al matrix and the Al 2 O 3 particles is almost at maximum (see Tab. 1). Therefore, it supports the occurrence of stress accumulation at the edges of the particles and the fracture and the erosion of the particles and particle clusters.