Synergetic strengthening effects on copper matrix induced by Al₂O₃ particle revealed from micro-scale mechanical deformation and microstructure evolutions

The micro-scale effect of Al₂O₃ particle on the deformation behaviors of the copper matrix was investigated using nanoindentation. Moderate strengthening effects were produced by the Al₂O₃ as indicated from the mechanical deformation evolutions. Specifically, the displacement recovery ratio and elastic work ratio is 6% and 9% higher for the Cu-5 wt% Al₂O₃ (C5A) composite material compared with that of the pure copper (PC) material, respectively. While for the indentation hardness and indentation modulus, the increment is 36% and 75%, respectively. Notably, the moderate strengthening effects were quantitatively illuminated from the power law index m for the C5A indent (1.2) and PC indent (1.1–1.3). In addition, synergetic strengthening effects were proposed from the microstructure evolutions in the C5A composite material. Specifically, the increment in yield strength deduced from the grain refinement is 120 MPa, which is 67% higher than that of the Al₂O₃ particle dispersion strengthening. The synergetic strengthening effects revealed from the microstructure evolutions are expected to provide new strengthening approaches for the ceramic particle reinforced metal matrix composite materials.