Fracture Resistance and Crack Growth Mechanisms in Functionally Graded Ti–TiB

Abstract This paper presents the results of fracture tests and crack path observations for a layered functionally graded material (FGM) consisting Ti TiB phases. The composition varied in nearly linear manner from TiB-rich layer at bottom to commercially pure (CP) top. Elastic properties mixed phase interlayers were measured using nanoindentation testing, demonstrating variation with composition. These differ significantly approximations calculated previous studies non-linear rule-of-mixtures approach. Fracture conducted on single edge notch bend [SEN(B)] specimens aligned orthogonal direction gradient. For this orientation, "average" R-curve behavior based J-integral was investigated understand mechanics growth. value J found be minimal (less than 1 N/mm) below 47 pct volume fraction compared reported approximately 150 N/mm Ti. indicate that steeper transition high concentrations metallic is necessary achieve adequate resistance metal/ceramic FGM. Observations specimen surface toughening mechanisms include bridging, branching, deflection.