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Effects of Grain-Boundary Sliding and Plastic Deformation of Grains on the Formation of Grain-Boundary Cracks in a Double Cylindrical Bicrystal of a Cu-SiO<SUB>2</SUB> Alloy

“…This is understood since the occurrence of GBS is a major reason for intergranular brittle fracturing of polycrystalline materials, in particular, those which contain small grain-boundary particles. 7,8) However, formation of the grain-boundary cracks was preferential and no cracks were observed in the same specimen D2 at the other diagonal locations, about % =4 and 5=4, where similarly large GBS was observed. The large grain-boundary crack in specimen D3 shown in Fig.…”

“…The testing temperature of 800 K was selected since significant intermediate temperature embrittlement is expected to occur for Cu polycrystalline alloys containing small oxide particles. 7,8) Deformation of the specimens was interrupted at certain strains and microstructural observations of the specimens were made after the tensile tests. Figure 3 shows the nominal stress-plastic strain curves, the -" curves, of the Cu-SiO 2 bicrystal at 800 K under 2 Â 10 À4 s À1 .…”

“…The Cu-SiO 2 alloy was selected since brittle grain-boundary fractures are expected to occur in Cu alloys when they contain small grain-boundary particles. 7,8) Although deformation behavior at room temperature has been studied for a Cu double cylindrical bicrystal, 9) fracture behavior of the bicrystal at elevated temperatures has not been studied.…”

Morphological Evolution of Grain-Boundary SiO2 in Internally Oxidized Cu-Si Bicrystals

“…The Cu-Si bicrystals were chemically polished using dilute nitric acid and were internally oxidized by the Rhines pack method [1][2][3][4][6][7][8][9][10] with the powder mixture of Cu:Cu 2 O:Al 2 O 3 = 1:1:2 (mass ratio). Using the Rhines pack method, the CuSi bicrystals are internally oxidized at Cu-Cu 2 O equilibrium oxygen partial pressure without the formation of an external Cu 2 O scale.…”

“…[1][2][3][4][5][6][7][8][9][10] This is called internal oxidation. Cu-base solid-solution alloys containing Si are known as a typical alloy system in which the internal oxidation generates an amorphous SiO 2 phase in grains and on grain boundaries (GBs).…”