The Influence of Microstructure on the Fracture Topography of Titanium Alloys

A survey is presented of the fracture topography observed in titanium and titanium alloys. Ductile fracture by microvoid nucleation, growth, and coalescence is of widespread occurrence in these alloys. It is usually possible to qualitatively relate the dimple size to the macroscopic ductility of the alloy. Titanium alloys may be embrittled by alloying additions which in most cases lead to a fine dispersion of second phase particles. In α-phase alloys such brittleness is associated with cleavage fracture; however, β-phase alloys, which exhibit cleavage-like macroscopic behavior, microscopically show evidence of small dimples. Environment often has dramatic effects on fracture behavior of titanium alloys, producing low-energy cleavage-like failure in both α and β-phases which are normally ductile. We attempt to relate the observations of fracture behavior and topography to structural and environmental factors.