Overview No. 3 Fracture-mechanism maps and their construction for f.c.c. metals and alloys

Abstract

Fracture-mechanism maps are diagrams with tensile stress as one axis and temperature as the other, showing the fields of dominance of a given micromechanism of fracture: cleavage, ductile fracture, rupture, intergranular creep fracture, and so on. Superimposed on the fields are contours of constant time-to-fracture. They can be constructed in either of two ways: empirically, by assembling observations and data for the fracture of a given material; or theoretically, via models for the individual fracture mechanisms. The first approach is developed here. Maps are presented for nickel, silver, copper, aluminium, lead and a number of their alloys. They give an overview of the micromechanisms by which a given material may fail, and help identify the one most likely to be dominant in a given experiment, or an engineering application. They should give guidance in selecting materials for high-temperature use and in the extrapolation of creep-rupture data.