V.M. Solaro, M. Bertoldi Acta Materialia 54(2006)4929-4937 AMZ Az40 Azo Fig 12. Failure stress as a function of the indentation load for the aMz engineered laminate and the reference monolithic ceramics. Fig. 10. SEM micrograph showing the architecture of the produced the AMZ laminate allows the calculation of B. Values equal to 0. 27 and 0.30 were obtained for AZo and AZ40 samples, respectively, modulus equal to 35+2 was calculated, clearly highlighted and both are substantially close to the theoretical value. by the very steep interpolating line shown in Fig. Il; this Conversely, for AZM B is equal to 0.01, confirming the result proves the high reliability of the engineered laminate independence of the strength from indentation load, i.e. produced in this work. Fracture strengths measured for samples subjected to AM ramin ates in a dpan gthe strengthes wt ln den te Irface damage by Vickers indentation are shown in design value Fig. 12. The he failure stress of engineered AMZ laminates appears to be independent of the indentation load, i.e. from the initial flaw size. Conversely, as expected, the strength of monolithic laminates is strongly dependent on the size of the indentation load, P, through the relation [1, 21] of where a is a constant depending on hardness, elastic mod- ulus and fracture toughness of the material and B=1/3 Fitting of the strength results for AZo and AZ40 shown in Fig. 12, using linear regression(in the log-log diagram) mm AMZ Az40 5.6586.0 X65 260M 45 SEI In g.(In MPa) Fig. 13. Typical fracture surfaces of the engineered laminate as observed Fig. Il. Weibull plot for the AMz engineered laminate and the reference by (a) optical microscopy and (b) scanning electron microscopy. The AZo and AZ40 monolithic ceramics surface in tension during the bending tests is marked as"tmodulus equal to 35 ± 2 was calculated, clearly highlighted by the very steep interpolating line shown in Fig. 11; this result proves the high reliability of the engineered laminate produced in this work. Fracture strengths measured for samples subjected to surface damage by Vickers indentation are shown in Fig. 12. The failure stress of engineered AMZ laminates appears to be independent of the indentation load, i.e. from the initial flaw size. Conversely, as expected, the strength of monolithic laminates is strongly dependent on the size of the indentation load, P, through the relation [1,21] rf ¼ a P b ; ð14Þ where a is a constant depending on hardness, elastic mod￾ulus and fracture toughness of the material and b = 1/3. Fitting of the strength results for AZ0 and AZ40 shown in Fig. 12, using linear regression (in the log–log diagram), allows the calculation of b. Values equal to 0.27 and 0.30 were obtained for AZ0 and AZ40 samples, respectively, and both are substantially close to the theoretical value. Conversely, for AZM b is equal to 0.01, confirming the independence of the strength from indentation load, i.e. from crack size. In addition, the strength of indented AMZ laminates (720 MPa) again compares well to the design value. Fig. 10. SEM micrograph showing the architecture of the produced the AMZ laminate. -4 -3 -2 -1 0 1 2 5.6 6.0 6.2 6.4 6.6 6.8 7.0 5.8 ln ln (1/(1-F)) ln σf (ln MPa) AMZ AZ0 AZ40 300 400 500 600 800 1000 σf (MPa) F (%) 99 90 50 20 10 5 Fig. 11. Weibull plot for the AMZ engineered laminate and the reference AZ0 and AZ40 monolithic ceramics. 0 200 400 600 800 10 100 σ f (MPa) indentation load (N) AMZ AZ40 AZ0 Fig. 12. Failure stress as a function of the indentation load for the AMZ engineered laminate and the reference monolithic ceramics. Fig. 13. Typical fracture surfaces of the engineered laminate as observed by (a) optical microscopy and (b) scanning electron microscopy. The surface in tension during the bending tests is marked as ‘‘t’’. 4936 V.M. Sglavo, M. Bertoldi / Acta Materialia 54 (2006) 4929–4937