Superposition of solid solution and oxide dispersion strengthening in the system [formula omitted]Au-SiO 2

Abstract

The critical resolved shear stress (CRSS) {tau}{sub t} of a particle strengthened material comprises two contributions: that of the solid solution matrix ({tau}{sub s}) and that due to the particles ({tau}{sub p}). Ebeling and Ashby measured the CRSSs of (1) pure Cu, (2) a homogeneous solid solution of Cu with 0.65at.%Au, (3) Cu with a volume fraction of 0.0066 SiO{sub 2}-particles, and (4) Cu containing 0.65at.%Au and a volume fraction of 0.0066 SiO{sub 2}-particles. The SiO{sub 2}-particles were produced by internal oxidation. Since they were incoherent they were bypassed by dislocations in the Orowan process. The authors made the crucial assumption that the presence of 0.65at.%Au had no effect on the growth of the SiO{sub 2}-particles, that is, they assumed that subjecting binary Cu00.18at.%Si-and ternary Cu-0.65at.%Au-0.18at.%-Si-specimens to the same internal oxidation treatment resulted in exactly the same dispersion of SiO{sub 2}-particles. On the basis of this assumption the authors concluded that solid solution (solved Au-atoms) and oxide dispersion (SiO{sub 2}-particles) strengthening superimpose linearly. In order to clarify the situation Ebeling and Ashby's experiments have been repeated under conditions which do not involve their crucial assumption about the growth of the SiO{sub 2}-particles. The system {und Cu}Au-SiO{sub 2} serves as amore » model system for the investigation of the superposition of solid solution and dispersion strengthening.« less