| Abstract Scope |
The intrinsic ductile-brittle transition is governed by the behavior at a sharp crack tip in a metal. Most metals emit dislocations, leading to blunting and, ultimately ductile failure. A transition to brittle behavior occurs if the crack tip undergoes cleavage prior to emission, leading to preservation of a sharp propagating crack. Investigation of dislocation emission, cleavage, and the criteria for this transition has a long history. Here, we show a recent analysis of crack tip emission that resolves fundamental problems with the classic Rice analysis. We then show several examples where the emission/cleavage competition is proposed to control brittle versus ductile behavior. The first example is Hydrogen embrittlement in FCC steels and high entropy alloys (HEAs). The second example is the brittle versus ductile behavior across refractory BCC High Entropy Alloys (HEAs) in the elemental family Cr-Hf-Mo-Nb-Ta-Ti-V-W-Zr. The third example is quasi-brittle failure in systems with interfaces that block dislocation propagation, work done in collaboration with Prof. Farkas. |