Synergistic toughening mechanism in 3Y–TZP/Nb composites

This paper focuses on the study of the flaw tolerance and resistance curve behaviour (R-curve) in 3Y–TZP/Nb composites containing indentation-induced small surface cracks. It has been found that toughening and resistance curve behaviour occurs as a result of the combined effects of crack bridging and transformation toughening. The ZrO₂–Nb composites are described as synergistically toughened composites due to anticipated interactions between crack bridging and stress-induced phase transformation. It has been found that these interactions produce a notable increase in toughness (K_ss ≈ 13 MPa m^1/2) greater than the sum of the combination that would be provided separately by the two types of reinforcement.